1766.     Head to Head Comparison of Magnetic Resonance Imaging and Multidetector Computed Tomography in Assessing Long-Term Effects of Microembolization on Myocardial Viability, Perfusion and Function

Maythem Saeed¹, Alastair Martin¹, Marcus Carlsson^1,2

¹UCSF, Dep of Radiology and Biomedical Imaging, San Francisco, CA, USA; ²Lund University Hospital, Dep of Clinical Physiology, Lund, Sweden

Microinfarction resulting from microembolized plaques is common in patients but diagnostic imaging tools are lacking. Therefore, this study determined the potential of MRI and 64-slice MDCT to quantify function, perfusion and viability in chronic microinfarction. The main findings were that both MRI and 64-slice MDCT could visualize and quantify chronic microinfarction and furthermore, the extent of microinfarction was comparable to histochemical staining. There was an excellent agreement between MDCT and MRI in measuring regional and global LV function and MRI had higher sensitivity to detect perfusion deficit in chronic microinfarction compared to MDCT.

                  1767.     Sequential Change in Myocardial Perfusion in Ischemic Heart Disease Post Percutaneous Coronary Intervention: A Longitudinal Study Using First-Pass Contrast-Enhanced MRI

Wan-Chen Shen¹, Mao-Yuan Marine Su², C-C Wu³, Y-W Wu³, W-C Chu², Wen-Yih Isaac Tseng⁴

¹National Taiwan University College of Medicine, Taipei, Taiwan; ²Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan; ³Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan; ⁴Center for Optoelectronic Biomedicine, National Taiwan University College of Medicine, Taipei, Taiwan

In this study, we perfored first-pass contrast-enhanced (FPCE) myocardial perfusion in a serial follow-up to determine the timing, magnitude and transmural difference of myocardial perfusion recovery by evaluating the change in stress perfusion, rest perfusion, and myocardial perfusion reserve (MPR).We have demonstrated that the myocardial perfusion in the ischemic regions can be restored as early as 24 hours after PCI, and perfusion in the inner wall of the myocardium improves more significantly than that in the outer wall.

                  1768.     Patients with Pulmonary Arterial Hypertension Have a Lower Left Ventricular Myocardial Perfusion Reserve on Cardiac MR Adenosine Stress Perfusion Imaging Compared to Age Matched Healthy Controls

Jan Skrok¹, Monda L. Shehata¹, Christopher Sibley², Thomas Goldstein³, Kyle McCommis³, Jie Zheng³, Joao A. Lima², David A. Bluemke⁴, Paul Hassoun⁵, Jens Vogel-Claussen¹

¹Department of Radiology, Johns Hopkins University, Baltimore, MD, USA; ²Department of Cardiology, Johns Hopkins University, USA; ³Mallinckrodt Institute of Radiology, Washington University School of Medicine, St.Louis, MO, USA; ⁴Department of Radiology, National Institutes of Health, Bethesda, MD, USA; ⁵Department of Pulmonology, Johns Hopkins University, USA

Patients with pulmonary arterial hypertension (PAH) are known to show cardiac remodeling. However, it is unknown whether myocardial blood flow under rest and adenosine-induced stress conditions is also affected. The purpose of our study was to compare left ventricular (LV) myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) between patients with PAH and age matched healthy volunteers using adenosine stress 1st pass perfusion cardiac MRI. Results show that patients with pulmonary arterial hypertension have a globally reduced left ventricular myocardial perfusion reserve compared to normal age matched controls. These changes are likely caused by microvascular dysfunction in PAH patients.

                  1769.     Cold Pressor Test in MRI for Quantitative Myocardial Perfusion Imaging

Andreas Weng¹, Christian Oliver Ritter¹, Max Kowalski¹, Meinrad Joachim Beer¹, Dietbert Hahn¹, Herbert Köstler¹

¹Institut für Röntgendiagnostik, Uniklinik Würzburg, Würzburg, Bayern, Germany

In this study a cold pressor test (CPT) was established in the MRI environment to investigate endothelial behavior and the resulting response of myocardial perfusion to sympathetic stimulation with cold. CPT was performed by putting the left hand of 10 healthy non-smoking volunteers in an over-head ice-water bath. For comparison 15 minutes later a rest examination was performed and a significant increase of myocardial perfusion could be observed in all volunteers.

                  1770.     Fully Automated Respiratory Motion Compensation in Myocardial Perfusion MRI Using Navigators

Henrik Pedersen¹, Steffen Ringgaard², Won Yong Kim²

¹Functional Imaging Unit, Glostrup Hospital, Glostrup, Denmark; ²MR Research Center, Aarhus University Hospital Skejby, Aarhus, Denmark

Correction of respiratory motion represents a major practical problem in quantitative myocardial perfusion MRI. This study presents a retrospective method of respiratory motion correction that is fully automated, insensitive to image brightness changes, and suitable for correcting respiratory motion artifacts in accelerated MRI. The proposed method uses additionally acquired respiratory navigators to predict non-rigid motion over the entire field-of-view. The underlying motion model is learned from a set of training images. Among the navigator and training configurations evaluated in this study, the optimum setup achieved an average 4-5 fold in-plane motion reduction in 32 myocardial perfusion MRI data sets.

                  1771.     Systolic 3D First-Pass Myocardial Perfusion MRI

Taehoon Shin¹, Padmini Varadarajan², Ramdas G. Pai², Gerald M. Pohost^1,3, Krishna S. Nayak¹

¹Department of Electrical Engineering, University of Southern California, Los Angeles, CA, USA; ²Division of Cardiology, Loma Linda University Medical Center, Loma Linda, CA, USA; ³Keck School of Medicine, University of Southern California, Los Angeles, CA

Three-dimensional (3D) MR first-pass myocardial perfusion imaging (MPI) is a promising alternative to conventional 2D multi-slice MPI, and typically involves acquiring data at mid-diastole where the heart is the most stationary. End-systole is the second longest quiescent period, and may be an opportune time interval for data collection due to its reduced sensitivity to heart rate variation and arrhythmia. To test this hypothesis, we have performed 3D MPI in healthy volunteers, which involved acquiring 3D perfusion time courses at both end-systole and mid-diastole. Image quality and time-intensity curves are compared.

                  1772.     Stress Myocardial Perfusion MRI at 3.0T with Improved Spatial and Temporal Resolutions by Using B1-Insensitive Water-Suppression and K-T SENSE Acceleration.

shingo kato¹, Hajime Sakuma, Shinichi Takase, Motonori Nagata, Nanaka Ishida, Kakuya Kitagawa, Masaki Ishida, Masaaki Ito, Makoto Obara², Kan Takeda

¹Mie Univ Hospital, Tsu,Mie, Japan; ²Philips Electronics Japan

Stress-rest myocardial perfusion MR images were acquired with high spatial resolution (<2mm) and temporal resolution (1-RR interval) by using k-t SENSE and 3.0T Imager. WET pulse was employed to obtain uniform 90 degree saturation in the increased B1 inhomogeneities at 3.0T., and to reduce beat-to-beat signal variation due to arrhythmia. In all 34 patients with suspected CAD who underwent the study, high resolution perfusion MR images were observed with reduced endocardial dark banding artifacts, allowing accurate detection of myocardial ischemia in patients with significant CAD with high sensitivity of 91.6% and specificity of 93.9%.

                  1773.     Myocardial Perfusion Imaging Using CAIPIRINHA Accelerated Multi-Slice Saturation Recovery TrueFISP

Daniel Stäb¹, Christian Oliver Ritter¹, Andreas Weng¹, Meinrad Joachim Beer¹, Marcel Gutberlet¹, Dietbert Hahn¹, Herbert Köstler¹

¹Institut für Roentgendiagnostik, Universitätsklinikum Würzburg, Würzburg, Bavaria, Germany

In this study a new technique for myocardial perfusion imaging was developed providing a full coverage of the heart and high signal-to-noise ratio (SNR) at the same time. A saturation recovery TrueFISP sequence providing high intrinsic SNR was combined with CAIPIRINHA accelerated multi-slice imaging exciting two slices simultaneously. Myocardial perfusion imaging was performed in 12 slices of the human heart during one first-pass experiment. The presented technique was considered to be also suitable for myocardial blood-flow quantification.

                  1774.     Unsupervised Inline Analysis of Cardiac Perfusion MRI

Hui Xue¹, Sven Zuehlsdorff², Peter Kellman³, Andrew Arai³, Sonia Nielles-Vallespin⁴, Christophe Chef D Hotel¹, Beatriz Paniagua¹, Christine Lorenz¹, Jens Guehring¹

¹Imaging and Visualization, Siemens Corporate Research, Princeton, NJ, USA; ²CMR Research and Development, Siemens Medical Solutions USA, Inc., Chicago, IL, USA; ³Laboratory of Cardiac Energetics, National Institutes of Health/NHLBI, Bethesda, MD, USA; ⁴MED MR PLM AW Cardiology, Siemens AG Healthcare Sector, Erlangen, Germany

No clinically accepted solution has emerged yet to automatically perform comprehensive analysis of first-pass myocardial perfusion MR data. We therefore propose a novel perfusion analysis scheme, including the steps of concatenated motion correction, adaptive noise suppression and perfusion parameter map generation. The solution has been integrated into the image reconstruction environment and does not require any user interaction. Results are typically available in less than one minute after the data acquisition is finished. The feasibility of proposed techniques was verified by in vivo studies on patients undergoing stress and rest first pass myocardial perfusion imaging.

                  1775.     Comparison of Myocardial Blood Flow Estimates from Dynamic Contrast-Enhanced Magnetic Resonance Imaging with Four Quantitative Analysis Methods

Nathan A. Pack¹, Edward V.R. DiBella¹, Christopher J. McGann¹

¹Dept. of Radiology, University of Utah, SLC, UT, USA

Quantitative estimates of myocardial blood flow in DCE-MRI studies have been published in recent years, though the absolute measures of blood flow have varied widely, possibly depending on what analysis method was used to analyze the dynamic perfusion data. In this work, four quantitative analysis methods (2-compartment modeling, Fermi function modeling, model-independent analysis, and Patlak plot analysis) were implemented and compared in 20 human subjects imaged at rest and adenosine stress. While there was good correlation between blood flow estimates between the four analysis methods, the absolute values of rest and stress blood flow were significantly different.

                  1776.     Quantification of Myocardial Blood Flow in the Presence of Remaining Contrast Agent - A Simulation Study

Dirk Ernst Johannes Cleppien¹, Georg Horstick², Stefan Weber¹, Wolfgang Günther Schreiber¹

¹Section of Medical Physics, Department of Radiology, Mainz University Clinical School, Mainz, Germany; ²Department of Cardiology, Mainz University Clinical School, Mainz, Germany

Quantification of myocardial blood flow (MBF) using dynamic contrast enhanced MRI is based on the relationship between signal intensity and concentration of administered contrast agent. In general, in MBF measurements this relationship is assumed to be linear, but in reality it’s more complex. Therefore, residual contrast agent from previous injections remaining in the blood also influences this relationship. In this study it is shown, that the quantification of MBF based on concentration time-courses produces more reliable values than that based on signal time-courses. In the latter case, the MBF is significantly underestimated and also notably influenced by residual contrast agent.

                  1777.     Comparison of the Quantitative First-Pass Myocardial Perfusion MRI with and Without Prospective Slice Tracking: Comparison Between Breath-Hold and Free-Breathing Condition

Dirk Ernst Johannes Cleppien¹, Georg Horstick², Nico Abegunewardene², Stefan Weber¹, Christian Ernst Mueller¹, Axel Heimann³, Karl-Friedrich Kreitner, Oliver Kempski³, Wolfgang Günther Schreiber¹

¹Section of Medical Physics, Department of Radiology, Mainz University Clinical School, Mainz, Germany; ²Department of Cardiology, Mainz University Clinical School, Mainz, Germany; ³Department of Neurosurgical Pathophysiology, Mainz University Clinical School, Mainz, Germany

Robust quantification of myocardial blood flow using dynamic contrast enhanced MRI depends strongly on the absence of respiratory heart motion. The common clinical approach uses breath-holding to minimize this problem, but in cases with a poor breath-hold the remaining motion renders reliable measurements almost impossible. As a result it may be hard to detect cardiac tissue with abnormal perfusion. Another approach for freezing heart’s motion is prospective slice tracking (PST). In this study PST was compared under free-breathing condition to breath-hold measurements. As a result PST significantly reduces variation of results induced by residual cardiac motion in both conditions.

                  1778.     Quantitative Contrast-Enhanced Myocardial Perfusion MRI: Simulation of Bolus Dispersion in Constricted Vessels

Dirk Graafen¹, Kerstin Münnemann¹, Stefan Weber¹, Wolfgang Günther Schreiber¹

¹Section of Medical Physics, Department of Radiology, Mainz University Medical School, Mainz, Germany

Using Computational Fluid Dynamics methodology dispersion of a contrast agent bolus was simulated in a straight vessel with different stenoses under steady state conditions. Two different perfusion conditions were examined under resting and stress condition. The dispersion in resting condition is more pronounced than under stress conditions. Therefore, resting myocardial blood flow may be more underestimated in quantitative myocardial perfusion studies than stress perfusion. In conclusion, a stenosis leads to underestimation of blood flow values, the amount depends in a complex way on their shape and degree.

                  1779.     Model-Free Maximum Likelihood Deconvolution (MLD): A Novel Perfusion Analysis Method in MRI to Calculate Myocardial Blood Flow

Omar El-Sherif¹, Robert Stodilka^1,2, Benoit Lewden¹, Michael Jerosch-Herold³, Terry Thompson^1,2, Frank Prato^1,2

¹University of Western Ontario - Lawson Health Research Institute, London, Ontario, Canada; ²Diagnostic Radiology, St. Joseph's Health Care, London, Ontario, Canada; ³Radiology, Brigham & Women's Hospital, Boston, MA, USA

We introduce a novel contrast enhanced perfusion analysis method – maximum likelihood deconvolution (MLD) – to estimate myocardial blood flow. MLD is designed to overcome difficulties that arise due to noise without compromising accuracy. MLD is evaluated using computer simulations and clinically in three volunteers. Simulation and clinical tests demonstrated that MLD is numerically stable and accurately estimates perfusion at clinical contrast:noise levels for cardiac perfusion values. MLD models dispersion of the contrast agent between the arterial and tissue curves, which is not usually accounted for by standard deconvolution analysis.

                  1780.     Improved Correction of Spatial Inhomogeneities by Surface Coils in Quantitative Analysis of First Pass Myocardial Perfusion

Frans P.P.J. Kremers¹, Mark B.M. Hofman², Jan G.J. Groothuis³, M Jerosch-Herold⁴, Aernout M. Beek³, Sven Zuehlsdorff⁵, Sonia Nielles-Vallespin⁶, Albert C. van Rossum³, Rob M. Heethaar¹

¹Physics & Medical Technology, ICaR-VU, VU University medical center, Amsterdam, Netherlands; ²Physics & Medical Technology,  ICaR-VU, VU University medical center, Amsterdam, Netherlands; ³Cardiology, ICaR-VU, VU University medical center, Amsterdam, Netherlands; ⁴Radiology, Brigham & Women’s Hospital, Boston, MA, USA; ⁵Siemens Medical Solutions USA Inc., Chicago, IL, USA; ⁶Siemens AG Healthcare Sector, Erlangen, Germany

Quantitative analysis of myocardial perfusion using deconvolution with the arterial input assumes equal signal sensitivity over the heart. When surface coils are applied, correction for differences in spatial sensitivity is required. Originally, this is applied by using the baseline signal in the myocardium before arrival of the contrast agent. Here we tested an image normalization using a 3D proton-density weighted pre-scan. This was tested in patients without CAD. Using pre-scan normalization similar mean perfusion values were found, but with reduced spatial variance over the heart. Thus, pre-scan normalization proves to be a valuable addition to quantitative analysis of myocardial perfusion.

                  1781.     Proton Spectroscopy Techniques to Examine Myocardial Metabolic State in Human Hearts Preserved for Transplantation

Matthias Peltz¹, Michael L. Cobert¹, Matthew E. Merritt², LaShondra M. West¹, Michael Erik Jessen¹

¹Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA; ²Advanced Imaging Center, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA

Perfusion preservation of hearts appears promising for extending the ischemic tolerance of myocardium. Predicting adequacy of myocardial preservation during storage is an important factor when hearts are stored for long intervals. We demonstrated in a human heart perfusion preservation model that proton high resolution MRS and magic angle spinning MRS could determine the metabolic state of preserved myocardium after 12 hour storage. These data suggest MRS may be a useful technique for evaluating donor hearts prior to transplantation.

                  1782.     Automated-Shim Approach to Facilitate ¹H-MRS in Mouse Hearts In Vivo

Jurgen E. Schneider¹, Hannah Barnes¹, Stefan Neubauer¹, Peter Jezzard²

¹Cardiovascular Medicine, University of Oxford, Oxford, Oxon, UK; ²FMRIB Centre, University of Oxford, Oxford, Oxon, UK

Good magnetic field homogeneity is essential for in vivo ¹H-MRS, but is particularly difficult to achieve in the heart. We implemented an automated cardiac shim approach in mice at 9.4T to aid routine metabolic phenotype characterization of normal and genetically modified mouse hearts at ultra-high magnetic fields. We demonstrated in this pilot study that the automated approach reproducibly optimized the B₀-field and subsequently allowed for a successful detection of cardiac ¹H-metabolites. Our work represents an important step towards increased ease, user-friendliness and applicability of cardiac MRS in vivo.

                  1783.     Cardiac Energetics of an Anoxia-Tolerant Heart: In Vivo 31P-NMR Studies of the Freshwater Turtle Trachemys Scripta

Jonathan A. W. Stecyk¹, Christian Bock², Johannes Overgaard³, Tobias Wang³, Anthony P. Farrell¹, Hans O. Pörtner²

¹University of British Columbia, Vancouver, BC, Canada; ²Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven, Germany; ³University of Aarhus, Aarhus, Denmark

The freshwater turtle Trachemys scrypta can tolerate anoxia for months in the cold, making it an ideal animal model for studies of cardiac energetics. Here, we used in vivo 31P-NMR to investigate the coupling between cardiac energetics and cardiac performance during anoxia at 21°C and 5°C. During anoxia high energy phosphates and intracellular pH displayed asymptotic patterns of change to a new steady state. The energetic shift correlated with the slowing of heart functioning at 5°C, but not at 21°C when bradycardia was elicited by autonomic control.

                  1784.     Detection of Myocardial Microvascular Disease in Latino Type-I Diabetes Mellitus Patients Using P-31 MRS

Hee-Won Kim¹, Gerald M. Pohost^1,2, Padmini Varadarajan², Rohit Varma³, Milena Ocon¹, Karam Souibri⁴, Rafit Drori⁵, Patrick Colletti¹, Adina E. Zeidler⁴

¹Radiology, University of Southern California, Los Angeles, CA, USA; ²Cardiology, Loma Linda University, Loma Linda, CA, USA; ³Ophthalmology, University of Southern California, USA; ⁴Medicine, University of Southern California, USA; ⁵Hillel Yaffe Medical Center, Hadera, Israel

The change of high energy phosphate in the heart during the stress was measured using stress cardiac P-31 MRS at 3T in order to identify impaired left ventricular function that is associated with reversible, exercise-induced metabolite alteration among Latino Type-1 diabetes mellitus (DM) patients. The significant drop of PCr/ATP during stress was found in 29% of overall patients and in 57% of the patients with retinopathy, while no significant drop in normal controls. Bioenergetic changes present among Type-1 DM patients may suggest systemic microvascular disorder, and the non-invasive P-31 cardiac MRS may facilitate the prediction of cardiomyopathy in such patients.

                  1785.     High Resolution Cardiac ³¹P 2D MRS Using an Actively Decoupled Coil Setup for Metabolic Phenotyping in Mice

Mahon L. Maguire¹, Hannah Barnes¹, Andrew Webb², Stefan Neubauer¹, Jurgen E. Schneider¹

¹Department of Cardiovascular Medicine, Oxford University, Oxford, Oxfordshire, UK; ²Department of Radiology, Leiden University Medical Center, Leiden, Netherlands

The mouse is the predominant species used in cardiac research. Both phosphocreatine and ATP levels are known to be perturbed in severe heart failure. Here we present the highest resolution mouse cardiac ³¹P chemical shift imaging data yet published. Acquired using a custom built actively decoupled coil arrangement with cardiac gating, and an acquisition weighted CSI pulse sequence, voxel sizes of 1.1x1.1x5.0 mm have been acquired within the context of a recovery experiment. This allows the possibility to directly interrogate high energy phosphate metabolism in a mouse model of heart failure within a longitudinal study of disease progression

                  1786.     Effect of Rapid Changes in ¹³C Pyruvate Concentration on Lactate and Alanine Pool Sizes and ¹³C Enrichment in the Heart

Karlos X. Moreno¹, Scott Sabelhaus¹, Matthew E. Merritt¹, A Dean Sherry¹, Craig R. Malloy¹

¹Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Tx, USA

Pyruvate binds to albumin. In the absence of albumin, the metabolic products of 2 mM hyperpolarized-[1-13C1]-pyruvate (HP-Pyr) are easily detected in the isolated heart but much higher [pyruvate] is required in the presence of albumin. The T1 of [1-13C1]-pyruvate is significantly reduced in the presence of albumin containing fatty acids and even more prominent in the presence of fatty acid-free albumin. Albumin catalyzes the relatively slow exchange of pyruvate methyl protons with solvent protons, suggesting transient covalent binding to albumin. The kinetics of these complex pyruvate/albumin interactions may play a significant role in hyperpolarized 13C imaging in vivo.

                  1787.     Estimates of the Appropriate Pyruvate Dose for Hyperpolarized ¹³C Cardiac Imaging

Karlos X. Moreno¹, Scott Sabelhaus¹, Matthew E. Merritt^1,2, A Dean Sherry^1,3, Craig R. Malloy^1,4

¹Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Tx, USA; ²Dept of Radiology, UT Southwestern Medical Center, Dallas, Tx, USA; ³Dept of Chemistry, Univ. of Texas at Dallas, Dallas, Tx, USA; ⁴Dept of Internal Medicine, UT Southwestern Medical Center, Dallas, Tx, USA

The heart oxidizes many substrates. The [pyruvate] necessary to compete effectively with long chain fatty acids, ketones, glucose and lactate was studied in rat hearts supplied with mixtures of substrates that mimic the fed or fasted state. 13C NMR isotopomer analysis showed that [pyruvate] even at 3 mM was oxidized at a high rate compared to fatty acids or ketones but a higher [pyruvate] was required under fasted state conditions. A transient reduction in cardiac output was observed at [pyruvate] > 10 mM. A minimum [pyruvate] of 3-6 mM would likely be required for cardiac exams.

                  1788.     Methods for Generating Propagating Shear Waves Within the Heart Using MR Elastography

Arunark Kolipaka¹, Kiaran P. McGee¹, Philip A. Araoz¹, Richard L. Ehman¹

¹Department of Radiology, Mayo Clinic, Rochester, MN, USA

MR elastography (MRE), a novel method for spatially resolving shear modulus is based on phase-contrast visualization of propagating shear waves within the object of interest. The technique has potential for a variety of cardiac applications but requires uniform propagation of shear waves throughout the myocardium. The aim of this study was to evaluate several methods of shear wave generation within the myocardium of a porcine animal model. Based on the root-mean-square amplitude of the induced shear waves, the optimal device is a single driver placed on the chest.

                  1789.     Calculation of Myocardial Stiffness Using a Rapid Multiphase MRE in a Heart Simulating Phantom

Arunark Kolipaka¹, Kiaran P. McGee¹, Philip A. Araoz¹, Kevin J. Glaser¹, Armando Manduca¹, Richard L. Ehman¹

¹Department of Radiology, Mayo Clinic, Rochester, MN, USA

MR elastography (MRE) is a new method for quantifying the mechanical properties of myocardium. Previously this technique has been applied to sample one point of the cardiac cycle. The purpose of this study was to compare stiffness estimates obtained using a multiphase to single-phase MRE technique in an object undergoing cyclic deformation. MRE derived stiffness estimates between the two methods are highly correlated with a significant reduction in the acquisition time was achieved with the multiphase technique.

                  1790.     MR Elastography as a Method for the Assessment of Myocardial Stiffness Throughout the Cardiac Cycle

Arunark Kolipaka¹, Kiaran P. McGee¹, Philip A. Araoz¹, Armando Manduca¹, Richard L. Ehman¹

¹Department of Radiology, Mayo Clinic, Rochester, MN, USA

A new MR elastography (MRE) cine sequence capable of spatially resolving the shear modulus of objects undergoing cyclic deformation was evaluated in an in vivo porcine model. Shear stiffness estimates of the myocardium throughout the cardiac cycle were calculated and indicate that myocardial stiffness is higher during systole than in diastole and the stiffness changes can be correlated with traditional pressure-volume analysis of cardiac function.

                  1791.     Assessment of Heart Function by Cardiac MR Elastography: Comparison to Left Ventricular Pressure Measurements

Thomas Elgeti¹, Michael Laule², Nicola Kaufels¹, Jörg Schnorr¹, Uwe Hamhaber³, Dieter Klatt¹, Sebastian Papazoglou¹, Carsten Warmuth¹, Bernd Hamm¹, Braun Juergen³, Ingolf Sack¹

¹Department of Radiology, Charité - University Medicine Berlin, Berlin, Germany; ²Clinic of Cardiology, Charité - University Medicine Berlin, Berlin, Germany; ³Institute of Medical Informatics, Charité - University Medicine Berlin, Berlin, Germany

MR elastography (MRE) is capable to measure myocardial elasticity changes without intervention. The aim of this study was to investigate the correlation between LV-pressure and cardiac MRE-signal. Therefore, MRE was applied to three minipigs displaying individual variations of heart rate, systolic and diastolic pressure and pressure gradients. Tip manometers mounted on catheters were used to directly acquire LV-pressure functions over time. A good correlation of Cardiac MRE with invasively observed LV-pressure changes was observed. Individual variations of LV-pressure differences could be reproduced by MRE.

                  1792.     Cardiac Cine MRI Reveals Ischemia-Reperfused Heart Suffers a Compromise in Its Function: P21 as an Oxygen-Sensitive Regulator of Fibrosis

Surya C. Gnyawali¹, Molly McCoy², Sashwati Roy², Chandan K. Sen²

¹Heart and Lung Research Institute, The Ohio State University, Columbus , OH, USA; ²Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA

p21 protein available in the myocardium worsens the heart function after ischemia and reperfusion (I-R). All of the cardiac functional parameters show significantly better outcomes in p21-knockout mice compared to its wild type. Which concludes that p21-dependent pathways contribute to post I-R myocardial fibrosis.

                  1793.     Restrictive Right Ventricular Physiology, Right Ventricular Fibrosis as Suggested by Cardiac Magnetic Resonance, and Exercise Capacity After Biventricular Repair of Pulmonary Atresia and Intact Ventricular Septum in Children

Wendy Wai Man Lam¹, Xue Cun Liang², Eddie Cheung², Alice KP Wu, Sophia J. Wong², Yiu fai Cheung²

¹Department of Radiology, Queen Mary Hospital, Hong Kong SAR, China; ²Division of Paediatric Cardiology, Queen Mary Hospital

We tested the hypothesis that RV restrictive physiology is prevalent and related to RV fibrosis and exercise capacity in patients after repair of pulmonary atresia and intact ventricular septum (PAIVS). Restrictive RV physiology was defined by presence of antegrade diastolic pulmonary flow and RV fibrosis assessed by late gadolinium enhancement (LGE) MR. They had higher RV LGE score. The score correlated negatively with exercise duration and with greater % predicted maximum oxygen consumption. In conclusion: restrictive RV physiology is prevalent in post-operative PAIVS patients. RV diastolic dysfunction is related to the magnitude of RV fibrosis and with better exercise capacity.

                  1794.     Prospective Synchronization of Small Animal Cardiac MRI: A Quantitative Comparison of an Optical Device, Pressure Sensor and ECG

Adrian Rengle¹, Raphaël Sablong¹, Olivier Beuf²

¹Université de Lyon, CREATIS-LRMN, CNRS UMR 5220; Inserm U630; INSA-Lyon; Université Lyon 1, Villeurbanne, France; ²Université de Lyon, CREATIS-LRMN, CNRS UMR 5220; Inserm U630; INSA-Lyon; Université Lyon 1, Villeurbanne, France

An optical-based device designed to synchronize MRI acquisition on small animals was developed using a transmit-receive pair of optical fibers. The suitability of the developed was assessed on ten mice and compared with ECG and pressure sensor for cardiac MRI. MR images of mice heart depict low visible motion artifacts with all three investigated signals used for triggering. No significant SNR differences were found on images acquired with three sensors. However, depending on device used, the triggering point does not correspond to the same instant of the cardiac cycle inducing a time shift between image series acquired with the three devices.

                  1795.     Comparison of Cardiac MR and 3D Echocardiography Left Ventricular Analysis

Job W.A. Gutteling¹, Ellemiek Wintjes², Pieter FF Wijn¹, Luc J.H.J. Theunissen³

¹Medical Physics, Máxima Medical Center, Veldhoven, Netherlands; ²Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands; ³Cardiology, Máxima Medical Center, Veldhoven, Netherlands

3D echocardiography (3DE) is evaluated as a readily available follow-up examination after Cardiac MR (CMR). Literature showed it underestimates LV volumes and is more variable. This study investigates the intrinsic reproducibility of both CMR and 3DE by repeatedly analyzing multiple datasets of two healthy volunteers with several software packages. Also, 20 patients were examined in a similar manner. LV volumes were larger with CMR than with 3DE, and although the CMR packages provided more reproducible results, 3DE analysis provides a valuable assessment of cardiac function.

                  1796.     Comprehensive Evaluation of Diastolic Function with MRI

Richard Thompson¹, June Cheng Baron¹, Kelvin Chow¹, Jessica Scott², Ben Esch², Mark Haykowsky³, Ian Paterson⁴

¹Biomedical Engineering, University of Alberta, Edmonton, AB, Canada; ²Cardiovascular Physiology and Rehabilitation Laboratory, University of British Columbia, Vancouver, BC, Canada; ³Physical Therapy, University of Alberta, Edmonton, AB, Canada; ⁴Division of Cardiology, University of Alberta, Edmonton, AB, Canada

Diastolic dysfunction is a contributing factor in most cardiovascular diseases. Ventricular relaxation is impaired prior to changes in systolic function and a third to a half of all cases of heart failure have preserved systolic function (LVEF >50%). Despite this prevalence, the importance of diastolic dysfunction in the many diverse manifestations of heart failure is not well characterized. We illustrate the measurement of conventional and novel diastolic parameters using universally available clinical MRI pulse sequences in healthy controls and a population of heart failure patients, highlighting the predominance of diastolic dysfunction in a diverse range of heart failure etiologies.

                  1797.     The Effects of Contrast Agent on Quantitative Morphological LV Parameters at 3T

Shona Matthew¹, Richard Stephen Nicholas², Stephen James Gandy³, Shelley Anne Waugh², Elena Crowe⁴, Richard A. Lerski², Malcolm H. Dunn¹, J Graeme Houston⁴

¹Physics and Astronomy, St Andrews University, St Andrews, Fife, UK; ²Medical Physics, Ninewells Hospital, Dundee, Tayside, UK; ³Medical Physics, Ninewells Hospital, Dundee, Fife, UK; ⁴Clinical Radiology, Ninewells Hospital, Dundee, Tayside, UK

This study addresses LV analysis at 3T in order to determine whether the administration of contrast agent has a significant effect on cardiac parameters. Pre and post contrast images of 12 healthy volunteers (no previous cardiac illness and Framingham score < 20%) were analysed. A paired t-test was performed on differences between mean pre and post contrast values of ejection fraction, end diastolic volume, end systolic volume, stroke volume, cardiac output and mass. Statistically significant differences were found for EDV, SV and mass which may impact on patient care. Findings also suggest normal ranges need to be established at 3T.

                  1798.     Determining Myocardial Function with Real-Time MRI

Andreas Weng¹, Christian Oliver Ritter¹, Heimo Stamm¹, Meinrad Joachim Beer¹, Dietbert Hahn¹, Herbert Köstler¹

¹Institut für Röntgendiagnostik, Uniklinik Würzburg, Würzburg, Bayern, Germany

In this study the accuracy and reliability of a non-breath-hold real-time MRI-technique for the determination of functional cardiac parameters was evaluated. TSENSE examinations were performed without ECG-triggering and in free breathing on 30 individuals. Resulting cardiac function parameters were compared to the ones acquired with common ECQ-triggered CINE examinations which required a breath-hold for every acquired slice.

                  1799.     Phased Array Imaging in Mouse Hearts Using an 8-Channel Phased Array Coil at 9.4 Tesla

Jurgen E. Schneider¹, Hannah Barnes¹, Matthias Müller², Stefan Neubauer¹, Titus Lanz²

¹Cardiovascular Medicine, University of Oxford, Oxford, Oxon, UK; ²RND, Rapid Biomedical, Rimpar, Germany

While the application of coil arrays and parallel imaging techniques are common in clinical cardiac MR, this technology is still in its infancy in ultra-high field, small-bore MR systems. This work presents first results for CMR in mice in vivo at 9.4T using a volume-coil-transmit/8-channel-volume-receive-array combination, and performs signal-to-noise-ratio (SNR) comparisons for different regions of heart as a function of selected coil-elements. It was found that all elements still add constructively to the SNR, although the main contribution to the image arises from the anterior coil elements as expected due to the off-centred positioning of the mice.

                  1800.     Ground Truth Evaluation of One Touch Cardiac Imaging

Robert D. Darrow¹, Vivek Vaidya², Rakesh Mullick², Ambey Govenkar³, Vincent B. Ho⁴, Maggie Fung⁵, Biju Varghese⁵, Thomas K. Foo¹

¹MRI Laboratory, GE Global Research Center, Niskayuna, NY, USA; ²Imaging Technologies, GE Global Research Center, Bangalore, India; ³Extenprise, Inc., Pune, India; ⁴Department of Radiological Sciences, Uniformed Services University of the Health Sciences, Bethesda, MD, USA; ⁵GE Healthcare, Waukesha, WI, USA

Traditionally, a skilled operator is required to perform a complex procedure such as a cardiac MR examination. The One Touch Cardiac (OTC) system, with cardiac feature recognition and intelligent scan subsystem, is capable of automatic acquisition of short-axis and long-axis slices, a critical component of a cardiac MR exam. With a single button push, it acquires a set of short-axis cardiac CINE images in about 7 minutes. Using OTC, cardiac images were collected from healthy volunteers, and scored by a cardiac radiologist. The scored accuracy of the system showed it is capable of producing images of diagnostic quality.

                  1801.     Whole Heart Cardiac MRI with High Temporal and Spatial Resolution Using a 128-Element Cardiac Array at 3 Tesla

Michael Hamm¹, Melanie Schmitt², Andreas Potthast², Sven Zuehlsdorff³, Lawrence L. Wald^4,5, David E. Sosnovik^4,6

¹Siemens Medical Solutions USA Inc., Charlestown, MA, USA; ²Siemens HealthCare, Erlangen, Germany; ³Siemens Medical Solutions USA Inc., Chicago, IL, USA; ⁴A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, USA; ⁵Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA; ⁶Harvard-MIT Division of Health Sciences and Technology,, Cambridge, MA, USA

We have recently reported the construction of a 128-channel receive coil at 3T. The aim of this study was to perform whole heart cine MRI in a single breath-hold with the 128-channel and to compare its performance with that of a 32-element array. Image quality was consistently better with the 128-elements than with the 32-element array, regardless of the acceleration protocol used. Our findings demonstrate whole heart cine imaging with both high spatial and temporal resolution can be robustly performed using TSENSE with 1D acceleration factors of 7 or greater.

                  1802.     High Temporal and Spatial Resolution Cine MRI for Characterizing Valvular and Cardiac Alterations in a Genetic Mouse Model of Valve Disease

Frank Kober¹, Stéphane Zaffran², Piotr Topilko³, Patrick J. Cozzone¹, Monique Bernard¹

¹Centre de Résonance Magnétique Biologique et Médicale (CRMBM), UMR CNRS N 6612, Faculté de Médecine, Université de la Méditerranée, Marseille, France; ²Institut de Biologie du Développement de Marseille-Luminy, CNRS UMR N 6216, Marseille, France; ³Biologie Moléculaire du Développement, Inserm U784, ENS, Paris, France

Lessons learned from valvulogenesis may provide insight into the molecular basis of adult valvular disease. The objective of this study was to detect potential valve defects and their consequences on left ventricular (LV) function and morphology in a krox20 knockout mouse model in vivo using high-resolution cine MRI.

                  1803.     Sub-Minute 3D Black-Blood Imaging of the Whole Heart with Isotropic Spatial Resolution

Jinnan Wang¹, Chun Yuan¹, Vasily L. Yarnykh¹

¹University of Washington, Seattle, WA, USA

Evaluation of cardiac morphology is an important part of routine diagnostic applications of cardiac MRI. A new blood suppression iMSDE (improved motion-sensitized driven equilibrium) method based on the flow dephasing effect has been recently proposed for vascular applications. In this study we aim to develop a novel reliable and time-efficient cardiac black-blood imaging method based on the iMSDE principle.

                  1804.     Respiratory and Cardiac Self-Gated Free-Breathing Cardiac CINE Imaging with Multi-Echo 3D Hybrid Radial Acquisition

Jing Liu¹, Pascal Spincemaille¹, Thanh D. Nguyen¹, Walter F. Block², Martin R. Prince¹, Yi Wang¹

¹Radiology, Weill Cornell Medical College, New York, NY, USA; ²Biomedical, University of Wisconsin - Madison, Madison, WI, USA

Free breathing 3D cardiac CINE imaging is achieved with simultaneous respiratory and cardiac self-gating. Multi-echo 3D hybrid radial acquisition technique has been applied to cardiac functional measurements and coronary imaging within a single breath-hold, providing high spatial and temporal resolutions. The acquired k-space centers along kz axis can be used for deriving the center of mass along slice encodes. During free breathing, this center of mass changes through time corresponding to both respiratory and cardiac motions, thus the center of mass along slice encodes can be used for simultaneous respiratory and cardiac gating. Results of short-axis, long-axis and four-chamber views demonstrated the proposed respiratory and cardiac self-gated 3D cardiac CINE imaging technique.

                  1805.     Comparison of Self Gated Cardiac MRI with Echocardiography for Determination of Left Ventricular Function in Rodent Models of Hypertrophy

kirsten Gilday¹, chris McCabe², William Matthew Holmes², Mhairi Macrae², anna Dominiczak¹

¹BHF Glasgow Cardiovacular Research Centre, University of Glasgow, UK; ²Clinical Neuroscience, University of Glasgow, Glasgow, Scotland, UK

The stroke-prone spontaneously hypertensive rat (SHRSP) is an excellent experimental model of essential hypertension. In addition, this strain demonstrates left ventricular hypertrophy. In humans, echocardiography and MRI are used as quick, non-invasive and accurate procedures for measuring cardiac parameters.The aim was to demonstrate the validity of echocardiography and self gated cardiac MRI as high fidelity, high throughput techniques for characterising cardiac differences in mass and function in 16 week old SHRSP, normotensive Wistar Kyoto (WKY) rats and the congenic strain SP.WKYGla14a.

                  1806.     3D Free-Breathing Radial Cine-SSFP Using a Retrospective Z-Center-Of-Mass Self Navigator: A Feasibility Study

Noel Christopher Codella¹, Pascal Spincemaille², Jing Liu², Ludovic de Rochefort², Bryan Kressler², Martin Prince², Yi Wang²

¹Physiology, Biophysics, and Systems Biology, Weill Cornell Medical College, New York, NY, USA; ²Radiology, Weill Cornell Medical College, New York, NY, USA

A free-breathing 3D radial cardiac cine-SSFP sequence was developed that uses the z axis center of mass self-navigator gating signal to monitor respiratory motion, eliminating slice misregistration and breath-holding problems in current clinical 2D SSFP sequence.

                  1807.     Three-Dimensional Whole-Heart Cine MRI Using Prospective Self-Gating for Compensation of Cardiac and Respiratory Motion

Robert Manka^1,2, Martin Bührer¹, Peter Bösiger¹, Sebastian Kozerke¹

¹Institute for Biomedical Engineering, Zürich, Switzerland; ²Department of Internal Medicine/Cardiology, German Heart Institute, Berlin, Germany

A 3D prospective self-gated technique for cardiac imaging was successfully implemented and enabled the accurate measurement of cardiac function and mass compared to standard multi-slice, multi-breathhold SSFP cine imaging.

                  1808.     Predictive Modelling of Cardiac Real-Time 2D Images

Henrik Pedersen¹, Henrik B.W. Larsson¹, Rasmus Larsen²

¹Functional Imaging Unit, Glostrup Hospital, Glostrup, Denmark; ²Image Analysis DTU Informatics, Technical University of Denmark, Lyngby, Denmark

Prediction of the respiratory and beating motion of the heart has several useful applications in cardiovascular MRI. Despite its usefulness, there is currently no available technique that establishes a predictive model of both cardiac and respiratory 3D motion. The main bottleneck is the inherent slow nature of MRI that prevents obtaining real-time 3D images of the heart with both high spatial and temporal resolution. In this work, we present a novel technique that predicts 2D real-time images for any cardiac and respiratory motion state. By combining several 2D acquisitions, the method predicts 3D images of the heart, including through-plane motion.

                  1809.     Retrospective Triggered Free Breathing Cardiac  Function with Respiratory Pencil Beam Navigators

Axel Bornstedt¹, Michael Radermacher¹, Vinzenz Hombach¹, Nico Merkle¹, Volker Rasche¹

¹Internal Medicine II, University Ulm, Ulm, Germany

Respiratory navigated free breathing cardiac function has the potential to replace standard cine breatholding for patients with restricted breatholding capabilities.

                  1810.     Evaluation of Coronary Stenosis in Rat: Toward the Development of a Chronic Hibernation Model

Karin Montet-Abou¹, Jean-Luc Daire¹, Jean-Pascal Jacob¹, Manuel Jorge-Costa², Denis R. Morel², Jean-Paul Vallee¹

¹Radiology, Geneva University Hospital and Faculty of Medicine, Geneva, Switzerland; ²Anesthesiological Investigation Unit, Geneva University Hospital, Geneva, Switzerland

Myocardial hibernation is a reversible state following chronic ischemia. Except for a very recent model of transgenic mouse no other rodent model has been developed. To fullfill this gap and understand hibernation we provoked partial stenosis of the left coronary artery. Magnetic Resonance Imaging permit to evaluate regional heart contraction and to class rats in four groups: normal, ischemic, hibernating, and infarcted pattern. Biological analysis of glycogen and lipid accumulation, troponin T disorganization, and fetal α smooth actin reexpression were shown. Although a variability of responses toward graded stenosis was obtained, MRI analysis permitted to discriminate different patterns following chronic ischemia.

                  1811.     Of Mice and Men: A Quantitative Comparison of 3D Cardiac Motion in Mice and Humans

Erica Dall'Armellina¹, Hannah Barnes¹, Stefan Neubauer¹, Steffen E. Petersen¹, Michael Markl², Jurgen E. Schneider¹, Bernd A. Jung²

¹Department of Cardiovascular Medicine, University of Oxford, Oxford, Oxon, UK; ²University Hospital Freiburg, Freiburg, Germany

Tissue Phase Mapping (TPM) is a well-established technique to assess regional cardiac function in humans [e.g. 1,2]. In mice, time course of the radial, rotational (i.e. tangential) and longitudinal velocity components of the myocardium have not been analysed as yet. The aim of our study was to perform a detailed analysis of transmural wall motion in normal mice, and to quantitatively compare the murine velocity patterns to those found in human hearts. We found that the motion pattern of normal mouse hearts is similar to the human heart, but the peak velocities in mice are a factor of ~3 lower for all velocity components compared to humans. Furthermore, the velocity twist in humans during systole between basal and more apical slices is inverted in mice

                  1812.     Fully Automated Segmentation of Long-Axis MRI Strain-Encoded (SENC) Images Using Active Shape Model (ASM)

Ahmed Amr Harouni¹, David A. Bluemke², Nael F. Osman^1,2

¹ECE Dept, Johns Hopkins University, Baltimore, MD, USA; ²Dept of Radiology, Johns Hopkins University, Baltimore, MD, USA

Active shape models can successfully locate and track the myocardium in noisy Strain-Encoded (SENC) images allowing radiologist to calculate strain curves for different myocardium regions immediately after acquiring the images with out any human assistance.

                  1813.     Analysis of True 3D Cardiac Motion Using 3D Tagged MRI

Yu Shimizu¹, Akira Amano¹, Tetsuya Matsuda¹

¹Biomedical Engineering Lab., Dep. of Systems Science, Kyoto University, Kyoto, Japan

Quantitative estimates of the heart wall motion enable differentiation between normal and diseased heart. Current challenge is the capture of its three-dimensional deformation during the cardiac cycle. Tagged MRI offers a non-invasive methodology to set tags in three dimensions, but has lacked attention due to the complexity in the 3D-tagtracking task. Here, we evaluated a high-resolution 3Dtagged cardiac MRtime-series to demonstrate that 3D tags allow for detailed quantification of local cardiac motion and in specific inherently 3D characteristics such as volume and stress/strain change. The latter is expected to provide valuable clues to the still largely unknown myo-cardiac cell orientation.

                  1814.     Fully Automatic 3D Cardiac Tagged MRI Analysis Using Multiple Source Non-Rigid Registration Techniques

Maria J. Ledesma-Carbayo¹, Ana Bajo¹, John Andrew Derbyshire², Andres Santos¹, Manuel Desco³, Elliot R. McVeigh⁴

¹Ingeniería Electrónica, Universidad Politécnica de Madrid, Madrid, Spain; ²Laboratory of Cardiac Energetics, National Heart, Lung & Blood Institute, National Institutes of Health, Bethesda, MD, USA; ³Unidad de Medicina y Cirugía Experimental, Hospital General Universitario Gregorio Marañon, Madrid, Spain; ⁴Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA

In this work, non-rigid image registration is used to estimate myocardial motion 3D Tagged MR datasets. The method proposed is a multi-source method that takes advantage of all the image information present in the short and long axis tagged images. Myocardial or tag segmentation is not required and therefore the method is completely unsupervised. The method has been evaluated with respect to the framework provided by the programs FindTags (tag segmentation) and Tag Tissue Tracker (motion field fitting). The evaluation was performed on experimental animal datasets achieving subpixel agreement between the fully automated tracking and the Findtags approach.

                  1815.     Strain Measurements with Displacement ENcoding with Stimulated Echoes (DENSE) Are Robust to Off Resonance

Meral Reyhan¹, J A. Derbyshire², Daniel Bruce Ennis¹

¹Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; ²National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA

The objective of this study was to define the effects of off-resonance on displacement and strain measures in a DENSE experiment using Bloch simulation and an analytic solution. Displacement errors from off-resonance for the stimulated-echo and stimulated-anti-echo are similarly sensitive to off-resonance. Off-resonance induced strain errors for the stimulated-echo are <0.2% for a wide range of off-resonance (0-10Hz) and strain values (±5% and ±20%). Off-resonance strain errors for the stimulated-anti-echo are <20% for ±5% strains and <10% for ±20% strains. The off-resonance induced strain error calculated from the stimulated-echo is robust to the effects of a wide range of off-resonances.

                  1816.     In Vivo Comparison of CSPAMM and DENSE for Cardiac Motion Analysis

Christian Torben Stoeck¹, A Crean², J P. Greenwood², P Boesiger¹, S Plein², S Kozerke¹

¹Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland; ²Academic Unit of Cardiovascular Medicine, University of Leeds, Leeds, UK

Displacement ENcoding with Stimulated Echoes (DENSE) and HARmonic Phase (HARP) analysis of Complementary SPAtial Modulation of Magnetization (CSPAMM) data have been proposed for cardiac motion analysis. Following the insight of the Fourier shift theorem, it has been argued that the information content of DENSE and HARP should be identical. In this study, DENSE and HARP data were obtained consecutively in the same subjects and compared in terms of circumferential shortening, rotation and time-to-peak motion of the heart with and without employing signal peak combination.

                  1817.     Assessment of Three Dimensional Left Ventricular Strain After VEGF Gene Therapy in Occlusive Infarction on Magnetic Resonance Imaging

Maythem Saeed¹, Marcus Carlsson^1,2, Demetrius Dicks¹, Alastair Martin¹, David Saloner¹

¹UCSF, Dep of Radiology and Biomedical Imaging, San Francisco, CA, USA; ²Lund University Hospital, Dep of Clinical Physiology, Lund, Sweden

Transendocardial delivery of vascular endothelial growth factor gene in infarcted and peri-infarcted myocardium under MR-guidance improved 3D (radial, circumferential and longitudinal) strain within 50 days and caused significant reduction in infarct transmurality of treated animals compared to controls. Cine and tagging MRI are sensitive techniques for monitoring the effects of locally delivered therapies.

                  1818.     Balanced Multi-Point Displacement Encoding for DENSE MRI: Theoretical and Experimental Results

Xiaodong Zhong^1,2, Patrick Helm³, Frederick H. Epstein^1,3

¹Biomedical Engineering, University of Virginia, Charlottesville, VA, USA; ²MR R&D Collaborations, Siemens Medical Solutions, Atlanta, GA, USA; ³Radiology, University of Virginia, Charlottesville, VA, USA

Various DENSE sequences have encoded displacement using a strategy analogous to the simple multi-point method for velocity-encoded phase contrast (PC) imaging. We developed general n-dimension balanced multi-point encoding for DENSE. Using these methods, phase noise variance decreased experimentally by 73.7%, 65.6%, and 61.9% compared to simple methods, which closely matched the theoretical decreases of 75%, 66.7%, and 62.5% for 1D, 2D and 3D encoding, respectively. Phase noise covariances decreased by 99.2% and 99.3% for balanced 2D and 3D encoding, consistent with the zero-covariance prediction. The direction bias inherent to the simple methods was decreased to almost zero using balanced methods.

                  1819.     Multiparametric T1 Weighted Imaging May Identify Carotid Plaque Components

General Leung^1,2, Rahul Sarkar², James Q. Zhan¹, Alan R. Moody¹

¹Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; ²Medical Biophysics, University of Toronto, Toronto, Ontario, Canada

Classification of plaque components may be helpful in evaluating patient prognosis. We present a method using pre and post contrast black blood as well as delayed contrast T1W imaging to identify plaque components. Histological correlation to H&E, CD31 and CD68 are also presented.

                  1820.     Assessment of Fibrous Cap Status of Carotid Artery Plaques by Contrast-Enhanced MRI

Robert Kwee^1,2, Werner Mess³, Robert van Oostenbrugge⁴, Cees Franke⁵, Floris Schreuder⁶, Arthur Korten⁷, Be Meems⁸, Joachim Wildberger^2,9, Jos van Engelshoven^2,9, Eline Kooi^2,9

¹Department of Radiology, Maastricht University Medical Center, Maastricht, Limburg, Netherlands; ²Cardiovascular Research Institute Maastricht, Maastricht, Netherlands; ³Department of Clinical Neurophysiology, Maastricht University Medical Center, Maastricht, Netherlands; ⁴Department of Neurology, Maastricht University Medical Center, Maastricht, Netherlands; ⁵Department of Neurology, Atrium Medical Center Heerlen, Heerlen, Netherlands; ⁶Department of Neurology, Maasland Hospital Sittard, Sittard, Netherlands; ⁷Department of Neurology, Laurentius Hospital Roermond, Roermond, Netherlands; ⁸Department of Neurology, Vie Curi Medical Center, Venlo, Netherlands; ⁹Department of Radiology, Maastricht University Medical Center, Maastricht, Netherlands

Overall reproducibility in identifying the fibrous cap of carotid artery plaques by non contrast-enhanced (CE-) MRI has shown to be poor. CE-MRI is capable of quantitatively measuring the dimensions of the intact fibrous cap. This study found good inter- and intraobserver agreement in assessing fibrous cap status on a per-plaque basis by using CE-MRI. Future prospective longitudinal studies can rely on CE-MRI to assess the predictive value of fibrous cap status of carotid artery plaques on the occurrence of cerebral ischemic events.

                  1821.     High-Resolution 3T Carotid MRI Identifies the High-Risk Lesion in Patients with Moderate (<70%) Carotid Stenosis

J. Kevin DeMarco¹, Hideki Ota¹, Hunter R. Underhill², David Zhu¹, Mat Reeves¹, Arshad Majid¹, Alonso Collar³, Minako Oikawa², Li Dong², Xihai Zhao², Feiyu Li², Vasily L. Yarnykh², Chun Yuan²

¹Michigan State University, East Lansing, MI, USA; ²University of Washington, Seattle, WA, USA; ³Great Lakes Heart Lung Institute, East Lansing, MI, USA

In order to improve the evaluation of carotid stenosis, we combined multi-contrast carotid plaque imaging with very high-resolution (0.28mm3) contrast-enhanced MRA at 3.0 T. Ninety-seven consecutive outpatients were studied. For the population as a whole and for subgroups of <70% and 70-99% stenosis, intraplaque hemorrhage, particularly Type I hemorrhage, was significantly associated with symptom status. In lesions with <70% stenosis by MRA, we found a strong association between fibrous cap status, intraplaque hemorrhage, and the size of the necrotic core with symptom. In patients with <70% stenosis, carotid plaque imaging may be able to distinguish between stable and unstable lesions.

                  1822.     Comparative Evaluations of 3D Turbo Spin Echo (TSE) Motion Sensitized Driven Equilibrium (MSDE) and 2D Double Inversion Recovery TSE Sequences for T1-Weighted Black-Blood Carotid Atherosclerosis Imaging

Daisuke Ito¹, Minako Oikawa¹, Hideki Ota², Makoto Obara³, Akira Suwa³, Isao Yanagisawa¹, Shoki Takahashi¹, Hiroaki Shimokawa¹

¹Tohoku University, Sendai, Miyagi, Japan; ²Michigan State University, USA; ³Philips

The purpose of this study is to compare 3D T1W MSDE-VISTA and 2D T1W DIR TSE for signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), and to determine if 3D MSDE-VISTA is potential replacement for conventional carotid 2D DIR TSE carotid plaque imaging. Compared to 2D DIR TSE, 3D MSDE-VISTA can achieve higher wall/lumen CNR and better blood suppression. 3D MSDE-VISTA has a potential to become alternative black-blood T1W imaging for carotid arteries with the advantage of 3D technique to aid in the evaluation of tortuous carotid arteries and facilitate co-registration of studies repeated over time.

                  1823.     Whole Body Three Dimensional Plaque Imaging

Yiu-Cho Chung¹, Georgeta Mihai², Orlando P. Simonetti², Sanjay Rajagopalan², Renate Jerecic³

¹Siemens Medical Solutions USA, Inc., Columbus, OH, USA; ²OSU Ross Heart Hospital, Columbus, OH; ³Siemens Medical Solutions USA, Inc., Chicago, IL

Atherosclerosis is a systemic disease. Current 2D MRI approaches for plaque imaging interrogate sections of the vascular systems that may not be representative of the disease’s systemic involvement. Also, 2D slices are less sensitive to plaque morphology changes in the slice direction, and slice gaps is difficult to account for in quantification. We propose a whole body 3D plaque imaging approach that covers vessels from neck to thigh. Volunteer studies showed that the approach can image a large vascular territory in an hour at isotropic voxel resolution between 0.8-1.2mm, demonstrating the approach’s clinical feasibility in the evaluation of vascular diseases.

                  1824.     Accelerated 3D Carotid Vessel Wall Imaging Using Compressed Sensing

Mahender K. Makhijani¹, Krishna S. Nayak¹

¹Electrical Engg., University of Southern California, Los Angeles, CA, USA

Multi-contrast high-resolution imaging is used to characterize carotid plaque components. 3D acquisitions are gaining acceptance but are susceptible to artifacts from swallowing during long scans. We investigate the acceleration of 3D inner volume Fast Spin-Echo imaging of the carotid wall using compressive sensing (CS). We examine the effect of CS reconstruction penalties and the sparsifying transform on image quality. We demonstrate repeatable artifact free reconstruction with up to 4x under-sampling, by using Total Variation and symmetric wavelets as the sparsifying transforms.

                  1825.     Effect of Cardiac Gating in High-Resolution MRI of the Carotid Vessel Wall

Rahul Sarkar¹, Alan R. Moody², General Leung²

¹Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; ²Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

While MR imaging of the carotid bifurcation has become a valuable tool in the detection and characterization of vascular disease, pulsatile arterial wall motion resulting from the cardiac cycle can result in blurring artefacts that diminish resolution and can cause the appearance of a thickened vessel wall. This study investigates the use of cardiac gating in high-resolution MRI to compensate for arterial wall motion in a healthy volunteer population.

                  1826.     Carotid Plaque Assessment Using Fast 3D Isotropic-Resolution Black-Blood MRI

Niranjan Balu¹, Vasily Yarnykh¹, Baocheng Chu¹, Jinnan Wang¹, Thomas Hatsukami², Chun Yuan¹

¹Radiology, University of Washington, Seattle, WA, USA; ²Surgery, University of Washington, Seattle, WA, USA

Carotid atherosclerotic plaque burden assessment and compositional analysis using black-blood MRI is currently limited by large slice thickness. We present a new 3D black-blood sequence (3D BB) to image the entire cervical carotid arteries with isotropic 0.7 mm voxel size in 2 minutes, thus ensuring patient compliance and diagnostic image quality. In-vivo identification of calcification, hemorrhage and lipid core using the 3D BB sequence was validated against standard carotid MRI sequences on 15 patients.with high sensitivity and specificity for detection of all three components. 3D BB is a promising new tool for comprehensive plaque assessment using a single sequence.

                  1827.     High Resolution Carotid Plaque MRI Using a Custom Gradient Coil Insert

Jordan P. Hulet¹, Seong-Eun Kim^2,3, John A. Roberts^2,3, Daniel R. Nightingale⁴, Gerald S. Treiman^5,6, Dennis L. Parker^2,3

¹Department of Biomedical Informatics, University of Utah, Salt Lake City, Ut, USA; ²Utah Center for Advanced Imaging Research, Salt Lake City, Ut; ³Department of Radiology, University of Utah; ⁴VA Salt Lake City Health Care System; ⁵Surgical Service, VA Salt Lake City Health Care System; ⁶Department of Surgery, University of Utah, School of Medicine

The utility of a custom gradient coil insert for scanning carotid plaques was assessed. The gradient coil insert works in conjunction with the whole body gradient system of a clinical scanner to increase overall gradient performance. Excised carotid plaques were imaged on a 3T clinical scanner with and without the gradient coil insert and images were compared. Plaque images obtained using the dual gradient mode had twice the spatial in-plane resolution of those obtained without it. This novel gradient system may be used to improve clinical carotid MR studies by increasing the resolution of in-vivo plaque images.

                  1828.     3D SPACE Arterial Wall Imaging with Prospective Self-Gating for Motion Compensation

Zhaoyang Fan^1,2, Sven Zuehlsdorff³, Peng Lai^1,2, Peter Weale³, Yiucho Chung³, Debiao Li^1,2

¹Radiology, Northwestern University, Chicago, IL, USA; ²Biomedical Engineering, Northwestern University, Evanston, IL, USA; ³Siemens Medical Solutions USA, Inc., Chicago, IL, USA

3D carotid wall imaging is prone to image artifacts caused by motion such as swallowing. In this work, we investigated the use of a self-gating method in a 3D variable-flip-angle TSE (SPACE) acquisition and implemented real-time motion detection and data acceptance or rejection. The feasibility was demonstrated at 3.0T in volunteers who was instructed to voluntarily swallow. Further evaluation of the effectiveness of this method in practical MRI is warranted. In addition, self-gating may have the potential to be combined with other 3D acquisition such as SSFP.

                  1829.     The Potential Problems Associated with Carotid Motion in Carotid Artery Imaging

Cheuk Fan Chan¹, Peter Gatehouse¹, Dudley John Pennell¹, David Firmin¹

¹Royal Brompton Hospital, London, UK

A high temporal-resolution interleaved study looking at how respiratory and swallowing motion may affect carotid artery imaging. We found that swallowing and previously considered insignificant respiratory motion have the potential to affect 2D and 3D image reliability and registration.

                  1830.     Halting the Effects of Flow Enhancement with Effective Intermittent Zeugmatographic Encoding (HEFEWEIZEN) in SSFP

Jamal Jon Derakhshan^1,2, Mark A. Griswold^1,2, Jeffrey L. Sunshine², Jeffrey L. Duerk^1,2

¹Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA; ²Radiology, University Hospitals of Cleveland, Cleveland, OH, USA

A new fast DB TrueFISP pulse sequence has been developed and applied to high resolution carotid artery imaging. Good flow suppression (> 80%) was achieved with a minor increase in the overall acquisition time (13%). TrueFISP magnetization evolution is maintained in the imaging slice throughout the acquisition, resulting in a low stationary signal disturbance (~10%). Using HEFEWEIZEN, it was possible to visualize moderate and severe carotid artery stenosis on high resolution TrueFISP images with a short acquisition time (<17 s).

                  1831.     Imaging of Carotid Artery Plaques: Correlation Between 18F-FDG-PET and MRI Findings

Robert Kwee¹, Robert van Oostenbrugge², Werner Mess³, Rob van der Geest⁴, Cees Franke⁵, Hans ter Berg⁶, Arthur Korten⁷, Be Meems⁸, Gerrit Teule⁹, Jos van Engelshoven¹⁰, Joachim Wildberger¹⁰, Eline Kooi¹⁰

¹Department of Radiology, Maastricht University Medical Center, Maastricht, Limburg, Netherlands; ²Department of Neurology, Maastricht University Medical Center, Maastricht, Netherlands; ³Department of Clinical Neurophysiology, Maastricht University Medical Center, Maastricht, Netherlands; ⁴Department of Radiology, Leiden University Medical Center, Leiden, Netherlands; ⁵Department of Neurology, Atrium Medical Center Heerlen, Heerlen, Netherlands; ⁶Department of Neurology, Maasland Hospital Sittard, Sittard, Netherlands; ⁷Department of Neurology, Laurentius Hospital Roermond, Roermond, Netherlands; ⁸Department of Neurology, Vie Curi Medical Center, Venlo, Netherlands; ⁹Department of Nuclear Medicine, Maastricht University Medical center, Maastricht, Netherlands; ¹⁰Department of Radiology, Maastricht University Medical Center, Maastricht, Netherlands

Noninvasive plaque imaging by 18F-FDG PET and MRI may be used to identify vulnerable plaques (i.e., plaques which have a high tendency to cause ischemic events). 18F-FDG PET is able to assess the severity of inflammation in carotid plaques, whereas MRI allows evaluation of morphological and compositional plaque characteristics. This study found no strong correlations between 18F-FDG PET and MRI-assessed morphological and compositional plaque characteristics. At present, 18F-FDG PET and MRI should be regarded as complementary (separate) imaging modalities. Future prospective longitudinal studies will determine whether 18F-FDG PET or MRI (or a combination) is most effective in identifying vulnerable plaques.

                  1832.     Non-Contrast-Enhanced MR Identification of Deep Vein Thrombosis: A Feasibility Study

Houman Mahallati^1,2, Michel Louis Lauzon^1,2, Linda Andersen^1,2, Richard Frayne^1,2

¹Radiology, University of Calgary, Calgary, AB, Canada; ²Seaman Family MR Research Centre, Foothills Medical Centre, Calgary Health Region, Calgary, AB, Canada

Pulmonary embolism (PE) is the third most common cause of death in the United States. The prevailing sources of emboli emanate from lower extremity deep vein thrombosis (DVT). PE is present in 60-80% of patients with DVT, although more than half of patients are asymptomatic. The clinical standard for identifying DVT is compression ultrasound, but imaging is typically limited to the thighs since the smaller calf veins are more difficult to visualize. Calf DVTs are, however, hypothesized to be clinically important, and so we are investigating high-resolution non-contrast-enhanced thrombus MR imaging from the thighs to the calves.

                  1833.     Quantification of Calcifications in Endarterectomy Samples by Means of High-Resolution Ultra-Short TE Imaging

Sonu Sharma¹, Axel Bornstedt¹, Said Boujraf¹, Volker Rasche¹

¹Internal Medicine II, University Ulm, Ulm, Germany

High-resolution ultra-short TE imaging was compared to conventional T1-weighted gradient echo imaging, volume CT and histology for quantification of calcifications in endarterectomy specimen.

                  1834.     Dual Echo Dynamic MRI Using Dy- Micelles and Gd-DTPA as a Contrast Agent

Venkatesh Mani¹, Claudia Calcagno¹, Karen C. Briley-Saebo¹, Zahi A. Fayad¹

¹Radiology, Mount Sinai School of Medicine, New York, NY, USA

Dynamic contrast enhanced MRI can examine tissue vascularization but cannot distinguish between perfusion and permeability effects. By injecting Gd-DTPA (extravascular contrast agent) concurrently with Dy-micelles (intravascular within the imaging time frame) and imaging them at different echo times, it might be possible to estimate both perfusion and permeability parameters simultaneously. The contrast agent with higher R1/R2 ratio (Gd) would primarily influence signal intensity in short echoes, while the contrast agent with very low R1/R2 ratio (Dy) would have limited effect on the signal intensity in the short echo while still affecting longer echoes, thereby potentially allowing dissection of different vascular properties of tissues. To evaluate feasibility of this approach, we tested relaxation properties of a mixture of different concentrations of Gd-DTPA and Dy-micelles in water and blood.

                  1835.     Plaque Progression in the ApoE-/- Mouse Model of Atherosclerosis Monitored in Three Vascular Beds

Basil Künnecke¹, Sabine Grüner², Jürgen Fingerle², Markus von Kienlin¹

¹Magnetic Resonance Imaging & Spectroscopy, F. Hoffmann-La Roche Ltd, Basel, Switzerland; ²Metabolic Disease Biology Area, F. Hoffmann-La Roche Ltd, Basel, Switzerland

Novel treatment strategies for atherosclerosis aim at plaque stabilisation and regression by plaque de-loading. The apolipoprotein-E-knockout (ApoE-/-) mouse is an accepted disease model for atherosclerosis that lends itself for preclinical drug intervention studies. Though imperatively needed in such studies, quantitative analysis of changes in plaque burden by conventional techniques is difficult in the light of slow disease progression and strong inter-individual variability. In the present large-scale MRI study on ApoE-/- mice we non-invasively assessed biological heterogeneity and successfully demonstrated plaque evolution in the three plaque-prone vascular beds comprising carotid arteries, aortic arch, and the innominate artery with putative vulnerable plaques.

                  1836.     Delayed Enhancement MRI of an in Vivo Model of Atherosclerotic Plaque Using a Blood-Pool Contrast Agent

Stephanie Elaine-GarWai Chiu¹, Alan R. Moody^1,2, James Q. Zhan², General Leung¹

¹Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; ²Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

This study compares vessel wall enhancement both minutes and 24 hours after the injection of a blood-pool contrast agent in a balloon injury animal model of atherosclerosis. High resolution MR imaging shows a ring of enhancement in the medial and adventitial layers of the injured segments which correlates to histologically proven proliferation of neovessels. Vasovist enhancement emphasizes the adluminal surface of the vessel wall during the first several minutes after contrast injection, while 24 hour delayed enhancement highlights areas of microvessel infiltration within the vessel wall.

                  1837.     Comparison of USPIO-Enhanced MRI and Magnetically Labelled Cell Tracking for Inflammation Detection in ApoE Mice

Olivia Monica Sigovan¹, Amine Bessaad¹, Hassan Alsaid¹, Genevieve De Souza¹, Claire Corot², Nicolas Provost³, Zouher Majd³, Christine Menager⁴, Norbert Nighoghossian¹, Serge Nataf⁵, Emmanuelle Canet-Soulas¹

¹CREATIS-LRMN Laboratory, University of Lyon, Lyon, France; ²Research, Guerbet, Paris, France; ³Technology Development, Genfit, Lille, France; ⁴Laboratoire Liquides Ioniques et Interfaces Chargées, Pierre et Marie Curie University, Paris, France; ⁵U842, INSERM, Lyon, France

There is a clinical need for a noninvasive atherosclerosis assessment. Two contrast-enhanced MR strategies were compared for detecting inflammation in atherosclerosis. Alipoprotein-E (ApoE) modified mice were investigated at 4.7T in a 4 day follow up. One group received a retro-orbital injection of a rapid pharmacokinetics USPIO (Guerbet, France). For the second group, magnetically labeled macrophages were administered. The free particle injection strategy allows reliable inflammation detection and has the advantage of being directly applicable in clinics. Magnetically labeled cell tracking enables a direct view of a specific cellular type, providing valuable information on the lesion inflammatory status.

                  1838.     Pharmacological Inhibition of CCR2 Decreases Macrophage Infiltration in the Aortic Root of the HuCCR2ki / ApoE-/- Mouse:  MRI Assessment

Gregory H. Turner¹, Alan R. Olzinski¹, Roberta E. Bernard¹, Heather Karr¹, Carla A. Cornejo¹, Karpagam Aravindhan¹, Bao Hoang¹, Robert N. Willette¹, Colin H. MacPhee¹, Clark A. Sehon¹, Peter J. Gough¹, Beat M. Jucker¹

¹GlaxoSmithKline, King of Prussia, PA, USA

The purpose of this study was to non-invasively assess the ability for a selective CCR2 antagonist to reduce the recruitment of macrophage to atherosclerotic lesions in a murine model of accelerated plaque growth. Therefore after 5 weeks of antagonist treatment in Ang II administered huCCR2ki/apoE-/- mice, USPIO MRI contrast agent was administered in order to non-invasively assess the macrophage burden in the aorta.

                  1839.     Detection of Atherosclerotic Plaques in the Aortic Arch Using Lipid-Based Contrast Agents

Brigit den Adel¹, Linda M. van der Graaf¹, Bianca Hogers¹, Glenda S. van Bochove², Marco C. Deruiter¹, Klaas Nicolay², Louise van der Weerd^1,3, Robert E. Poelmann¹

¹Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, Netherlands; ²Department of Biomedical Engineering, Eindhoven University, Eindhoven, Netherlands; ³Department of Radiology, Leiden University Medical Center, Leiden, Netherlands

Despite the wide range of methods to generate contrast with MRI, it is difficult to discriminate intimal thickening and atherosclerotic lesions from healthy vesseld using intrinsic MRI contrast mechanisms, especially in moving structures like the aortic arch. We aim to determine the kinetics of lipid-based Gd-containing contrast agents for in vivo visualization of atherosclerotic in the aortic arch of ApolipoproteinE deficient mice. Retrospective gated cine MRI of the aortic arch allows to visualize passive contrast enhancement in atherosclerotic plaques. Different Gd-containing contrast agents were shown to have different kinetics, and optimal imaging has to be assessed by longitudinal follow-up.

                  1840.     Atherosclerotic Plaques MRI Detection in ApoE -/- Mice Using the Blood Pool Agent B22956/1

Claudia Cabella¹, Giulia Chiesa², Vito Lorusso¹, Alessandro Maiocchi¹, Marta Marchesi², Luigi Miragoli¹, Cinzia Parolini², Luisa Poggi¹, Fabio Tedoldi¹, Fulvio Uggeri¹, Giovanni Valbusa¹

¹Bracco Imaging SpA, Colleretto Giacosa, Turin, Italy; ²Dipartimento Scienze Farmacologiche, University of Milan, Milan, Mi, Italy

Development of new, non-invasive, diagnostic tools aimed to detect the occurrence of atherosclerotic plaques is a primary task in medical research, due to the impact of atherosclerosis-induced diseases on the world population health. In this study, using ApoE -/- mice as animal model and hystologic analysis as reference standard, we showed that the use of the blood pool contrast agent B22956/1 strongly improves the sensitivity of MRI in detecting spontaneously occurring human-like atherosclerotic lesions, thanks to the strong albumin binding of this molecule, which increases the intravascular persisting time and thus the chance to permeate altered endothelial tissues.

                  1841.     Comparison of Segmented and Single-Shot DENSE MRI of the Carotid Arteries at 3T

Alexander Peter Lin^1,2, Scott Fraser¹, Han Wen²

¹Biochemistry and Molecular Biophysics, California Institute of Technology, Pasadena, CA, USA; ²National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA

Displacement encoding with stimulated echoes (DENSE) MRI provides quantitative strain measurements of the biomechanical function of vessel wall motion. The goal of the study is to compare the previously validated segmented sequence with the single shot implementation. Results show that the single shot sequence with rigid body image registration removes in-plane flow artifacts, particularly above the bifurcation, and motion artifacts due to swallowing and neck motion which increases the reproducibility and accuracy of strain measurements in the carotid arteries. This allows for optimal in vivo characterization of atherosclerotic plaque in future studies.

                  1842.     3.0 Tesla MRI Common Carotid Wall Shear Stress Measurements: Correlations with Common Carotid Arterial Wall Thickness.

Raphael Duivenvoorden¹, Eric de Groot, Ed van Bavel², Ramsi Amri, Erik Stroes, J. Lameris³, J. Kastelein, Aart J. Nederveen³

¹Vascular Medicine, Academic Medical Center, Amsterdam, Netherlands; ²Medical Physics, Academic Medical Center; ³Radiology, Academic Medical Center

Wall shear stress (WSS) is an important parameter in the assessment of atherogenesis. Increase of arterial wall volume is believed to be associated with lower wall shear stresses. Here we measure both parameters in a group of 45 subjects using 3.0 Tesla MRI. For both diastolic and systolic WSS significant correlations between WSS and mean wall area could be calculated, suggesting that MRI WSS determination is a promising tool for studying vessel wall function.

                  1843.     Mechanical Stress Levels in Symptomatic Patients Scheduled for Carotid Endarterectomy

Samuel Alberg Kock¹, Jens Vinge Nygaard², Anders Niemann¹, Anette Klærke³, Nikolaj Eldrup³, Søren Dalager⁴, William Paaske³, Won Yong Kim^1,5

¹MR-Center, Aarhus University Hospital Skejby, Aarhus, DK, Denmark; ²Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, DK, Denmark; ³Dept. of Vascular Surgery, Aarhus University Hospital Skejby, Aarhus, DK, Denmark; ⁴Dept. of Pathology, Aarhus University Hospital, Aarhus, DK, Denmark; ⁵Dept. of Cardiology B, Aarhus University Hospital Skejby, Aarhus, DK, Denmark

Mechanical stress levels were calculated using computational fluid dynamics simulations based on MRI data in nineteen symptomatic carotid patients using an improved method allowing for fast simulations in clinically relevant simulation times. Stress levels were compared to known predictors of plaque vulnerability and shown to correlate significantly with fibrous cap thickness and the degree of stenosis. Evaluation of longitudinal mechanical stress levels may improve risk assessment in patients with carotid atherosclerosis.

                  1844.     Local –not Global- Maximal Structural Stress Associates with Vulnerable Plaque Features

Gador Canton¹, Li Dong¹, Hunter R. Underhill¹, William S. Kerwin¹, Zhongzhao Teng², Dalin Tang², Baocheng Chu¹, Thomas S. Hatsukami³, Chun Yuan¹

¹Radiology, University of Washington, Seattle, WA, USA; ²Mathematical Sciences, Worcester Polytechnic Institute, Worcester, MA, USA; ³Surgery, University of Washington, Seattle, WA, USA

The aim of this study was to determine the association between morphological features associated to high-risk carotid atherosclerotic plaque as measured by MRI and both the local and the global maximal structural stress. In vivo carotid MRI is used to render the arterial geometry and plaque morphological features as well as to measure the fibrous cap thickness. A finite element method is used to solve the equations governing the wall mechanics

                  1845.     Circumferential Cyclic Strain in the Abdominal Aorta: Comparison of a Phase-Contrast Magnetic Resonance Imaging Vs. a FIESTA Method

Janice J. Yeung^1,2, Andrea S. Les¹, Jinha M. Park³, Robert J. Herfkens³, Ronald L. Dalman², Charles A. Taylor^1,2

¹Bioengineering, Stanford University, Stanford, CA, USA; ²Surgery, Stanford University, Stanford, CA, USA; ³Radiology, Stanford University

We 1) report in vivo circumferential cyclic strain measurements in the supraceliac and infrarenal aorta of healthy subjects, using segmented vessel diameters to calculate the Green-Lagrange strain; and 2) compare results from a PC-MRI sequence vs. a bright-blood FIESTA sequence, using thresholding and manual segmentation techniques. Supraceliac and infrarenal strain levels were similar. Strain curves from FIESTA scans were cleaner and agreed with previous studies in strain and deformation levels. The FIESTA technique, which gives excellent tissue contrast regardless of flow, should be used to measure wall strain in preference to PC-MRI, which yields blurry vessel edges during diastole.

                  1846.     Imaging High-Speed Jets Using Rapid Ungated Fourier Velocity Encoding

Hattie Zhi Chen Dong¹, Bob S. Hu^1,2, Juan M. Santos¹, Dwight G. Nishimura¹

¹Electrical Engineering, Stanford University, Stanford, CA, USA; ²Cardiology, Palo Alto Medical Foundation, Palo Alto, CA, USA

We propose the use of a rapid ungated Fourier velocity encoding (FVE) sequence for imaging high-speed jets. The sequence is made compact with FVE in the slice-select direction and readout perpendicular to the flow direction. It is applied continuously in an ungated fashion, producing an accurate time-averaged velocity spectrum in just a few seconds by averaging all k-space data. Phantom experiments and in vivo scans demonstrate the ability of this method to image high-speed jets, and results are verified using Doppler ultrasound.

                  1847.     Aortic Stiffness Is Related to Left Ventricular Diastolic Dysfunction in Heart Failure with Normal Ejection Fraction as Measured by MRI

ElSayed H. Ibrahim¹, Alan Miller¹, Richard D. White¹

¹University of Florida, Jacksonville, FL, USA

Congestive heart failure is a major cause of morbidity and mortality in the western world and is the leading cause of hospitalization in older patients. However, over one third of patients with decompensated heart failure have normal left ventricular systolic function (heart failure with normal ejection fraction (HFNEF)). This condition occurs when left ventricular filling and relaxation are impaired during the diastolic phase of the cardiac cycle. In this work, patients with HFNEF are imaged with MRI to measure the degree of aortic stiffness and diastolic dysfunction. The relationship between the resulting measurements is studied and compared to normal volunteers.

                  1848.     Estimation of Local Aortic Pulse Wave Velocity in a Single Heartbeat

Michael C. Langham¹, Jeremy Magland¹, Felix W. Wehrli¹

¹Radiology, University of Pennsylvania, Philadelphia, PA, USA

At the early systolic phase it is assumed that the pulse wave is unidirectional and reflectionless. From this assumption pulse wave velocity (PWV) can be can be expressed as PWV = δQ/δA, where δQ and δA represent temporal changes in the blood flow rate and cross-sectional area of the aorta. We present an MRI technique unaffected by irregular heart rhythm (which is normal) since PWV is estimated during a single heartbeat. The derived PWV = 2.5 m/s, which is somewhat lower than those found in literature for a healthy subject. Sources of error are deviations of aortic circularity.

                  1849.     Different Techniques for Measuring Aortic Pulse Wave Velocity Using Magnetic Resonance Imaging

ElSayed H. Ibrahim¹, Kevin R. Johnson¹, Richard D. White¹

¹University of Florida, Jacksonville, FL, USA

The aorta is a basic determiner of the total systemic compliance. Reduced aortic compliance has shown to correlate with different pathologic states. Recently, noninvasive measurements have been made with MRI to calculate the blood pulse wave velocity (PWV) inside the vessel, which is inversely related to arterial stiffness. In this work, different techniques for estimating PWV (transit-time, flow-area, and cross-correlation techniques) are tested on human subjects with different cardiac conditions and compared to each other. Inter-observer, intra-observer, and scan-rescan variabilities are reported, along with the advantages and disadvantages of each technique.

                  1850.     Regional Transit Time Measurement of Pulse Wave Velocity in the Murine Aorta

Marco Parczyk¹, Volker Herold¹, Gert Klug², Peter Michael Jakob¹, Wolfgang Rudolf Bauer², Eberhard Rommel¹

¹Departement of Experimental Physics 5, University of Würzburg, Würzburg, Bavaria, Germany; ²Medizinische Universitätsklinik, University of Würzburg, Würzburg, Bavaria, Germany

An MR-technique to measure the pulse wave velocity in the murine aorta is presented here. Aortic stiffness increases in early stages of arteriosclerosis and is assessable by pulse wave velocity (PWV) MR-measurements. So far literature reported only MR-studies in larger animals and humans. As pulse wave and flow velocities are similar in humans and mice, but dimensions are about 20-times larger in humans, the challenges in this project were especially the temporal and spatial resolutions needed. The MR-technique was validated and pulse wave velocities in eight-month-old apolipoprotein E deficient mice and a control group were determined.

                  1851.     Deformation, Strain, and Pressure-Strain Elastic Modulus at the Supraceliac, Infrarenal, and Mid-Aneurysm Levels in the Aneurysmal Abdominal Aorta

Andrea Seba Les¹, Janice J. Yeung², Geoffrey M. Schultz², Robert J. Herfkens³, Ronald L. Dalman², Charles A. Taylor

¹Bioengineering, Stanford University, Stanford, CA, USA; ²Department of Vascular Surgery, Stanford University; ³Radiology, Stanford University

We used a cardiac-gated cine FIESTA sequence to measure luminal deformation, circumferential Green-Lagrange strain (E_{&[theta]&[theta]}) and pressure-strain elastic modulus (E_p) at the supraceliac (SC), infrarenal (IR), and mid-aneurysm (MA) locations in fourteen men with abdominal aortic aneurysm. E_{&[theta]&[theta]} and E_p were statisically significantly different between the SC and MA (p<0.00001 and p<0.0005) and IR and MA locations (p<0.0005 and p<0.0005). The deformations (SC, 1.67±0.38 mm; IR, 1.15±0.29 mm; MA 0.88±0.25 mm) were statistically significantly different between all locations. The E_p at the MA location was similar to values obtained via ultrasound.

                  1852.     Mean Pulmonary Arterial Pressure Estimation by High Temporal Resolution Phase-Contrast MR Imaging in Patients with Chronic Thromboembolic Pulmonary Hypertension (CTEPH) and Correlation with Simultaneous Invasive Pressure Recordings – First Results

Stefan Weber¹, Gesine Maria Wirth, R Peter Kunz, Michael B. Pitton, E Mayer², Chistoph Düber, Karl Friedrich Kreitner

¹Section of Medical Physics, Department of Radiology, Mainz University Medical School, Mainz, Germany; ²Department of Cardiothoracic and Vascular Surgery, Mainz University Medical School, Mainz, Germany

The aim of this study was to validate the estimation of the mean pulmonary artery pressure (mPAP) using high temporal resolution phase-contrast magnetic resonance flow measurements with invasive catheter-based pressure measurement. Seven patients with chronic thromboembolic pulmonary hypertension (CTEPH) underwent simultanously acquired catheter-based pressure measurement and high temporal resolution phase-contrast MRI. A very high correlation of calculated mPAP values from MRI data derived from flow parameters and invasive measured mPAP was found (R=0.99). Therefore, non-invasive mPAP-estimations are possible in CTEPH-patients by means of high temporal resolution PC-MRI and correlate well with simultaneous invasively measured values.

                  1853.     Time-Resolved Blood Flow Quantification with Ungated Radial Sampling

Michael C. Langham¹, Jeremy Magland¹, Felix W. Wehrli¹

¹Radiology, University of Pennsylvania, Philadelphia, PA, USA

Flow quantification with Cartesian scan is susceptible to ghosting flow artifact due to phase and amplitude modulation from pulsatile flow and normal dynamic heart rhythm. We propose a method where external trigger is obviated by a continuous radial scanning. The velocity-encoded radial samplings along each view angle are reordered by taking complex difference between successive projections. Results clearly demonstrate that radial flow quantification largely eliminates flow artifacts and flow profile is consistent with the standard gated PC-MRI with Cartesian sampling. Small discrepancy was observed during the diastole, where the effect of dynamic heart rhythm is more pronounced.

                  1854.     Flow Quantification in the Heart Chambers: 3D PC-SSFP Compared with Spoiled GE

Marijn P. Rolf¹, Mark B.M. Hofman¹, Joost P.A. Kuijer¹, Albert C. van Rossum², Rob M. Heethaar¹

¹Physics and Medical Technology, ICaR-VU, VU University Medical Center, Amsterdam, Netherlands; ²Cardiology, ICaR-VU, VU University Medical Center, Amsterdam, Netherlands

This study evaluated the flow quantification properties of a new 3D PC-SSFP sequence. In vitro, flow measurements matched with regular flow meters and with 3D PC-GE measurements. In vivo, at the descending aorta the PC-SSFP correlated well with PC-GE. Measurements at the mitral valve level showed good correlation with 3D PC-GE for peak velocities, whereas mean flow showed only moderate correlation. Nevertheless, the mean flow repeatability of PC-SSFP was better than PC-GE, as can be explained by the higher contrast-to-noise ratio within the heart chambers, supporting positioning of the ROI. Therefore, this new sequence provides improved cardiac flow imaging.

                  1855.     Undersampled Spirals for Real-Time Flow Measurements

Jennifer Edgar¹, Vivek Muthurangu², Andrew Taylor², David Atkinson¹

¹Medical Physics, University College London, Malet Place Engineering Building, London, UK; ²Cardiovascular MR, UCL Institute of Child Health, London, UK

Real-time flow measurements are time efficient and have the ability to measure flow in patients with cardiac arrhythmias. We have developed undersampled spiral flow sequences which allow real-time capabilities. We compared flow results from a reference, gated flow sequence to spiral sequences with uniform density reconstructed with SENSE (R=3, R=4), spiral sequences with variable density reconstructed with SENSE (R=3, R=4) and to spiral sequences with variable density reconstructed with kt-SENSE (R=3, R=4). It was found that in a flow phantom and in 2 volunteers all of the methods tested produced comparable results.

                  1856.     Investigating the Potential of MRI as a New Non-Invasive Modality for Wave Intensity Analysis (WIA) in Healthy and Renal Disease Subjects

Celine Quinsac¹, Alan Jackson², Philip Kalra³, Helen Eddington³, Paul Dark³

¹Imaging Science and Biomedical Engineering, School of Cancer and Imaging Sciences , The University of Manchester, Manchester, UK; ²Imaging Science and Biomedical Engineering, School of Cancer and Imaging Sciences, The University of Manchester, Manchester, UK; ³School of Translational Medicine, The University of Manchester, Manchester, UK

This work investigated the potential to perform systemic arterial input Wave Intensity Analysis (WIA) using one-dimensional MR blood velocity measurements in the ascending aorta taken in association with blood pressure waveforms recorded using wrist applanation tonometry. Wave Intensity Analysis (WIA) was performed in both healthy volunteers and patients with chronic renal dysfunction already known to have increased arterial stiffness. Using these non-invasive measurement modalities, WIA was successful in showing higher systolic blood pressure, wave reflection and wave speed in the patient group, indicators of decreased arterial compliance.

                  1857.     Robust Estimation of Changes in Transverse Relaxation from Magnitude MRI Data: Application to Vessel Size Imaging

Simon Walker-Samuel¹, Matthew Orton¹, Lesley D. McPhail¹, Simon P. Robinson¹

¹Cancer Research UK Clinical Magnetic Resonance Research Group, Institute of Cancer Research, Sutton, Surrey, UK

Vessel size imaging using USPIO contrast agents has recently been utilised in a range of contexts, but has been reported to suffer from over-estimation of vessel size index (VSI). In this study, a novel Bayesian maximum a posteriori (MAP) approach is presented for estimating ÄR2 and ÄR2* and ADC. This is compared with a conventional approach (least-squares, LS). By conditioning data with the removal of parameter estimates with high uncertainties or non-significant enhancement, VSI was estimated at 83±29ìm by LS and 63±25ìm by MAP (difference significant, p<0.01), compared with 67±6ìm from histological measurements.

                  1858.     MRI Turbulence Quantification

Petter Dyverfeldt¹, Roland Gårdhagen¹, Andreas Sigfridsson¹, Matts Karlsson¹, Tino Ebbers¹

¹Linköping University and Center for Medical Image Science and Visualization (CMIV), Linköping, Sweden

Turbulent flow may contribute to the progression and hemodynamic consequences several cardiovascular diseases. MR turbulence measurements were recently successfully applied in-vivo and an in-vitro study has demonstrated good agreement between turbulence quantities obtained by MRI and particle image velocimetry. In this study our objective was to investigate potential pitfalls and sources of error in MR turbulence measurements. The results showed that the sensitivity of MRI turbulence measurements to non-turbulent phenomena is negligible and that robust and accurate estimates of turbulence intensity can be obtained from a standard phase-contrast MRI measurement. These findings may enhance the applicability of MR turbulence measurements.

                  1859.     In Vivo Measurement of Regional and Local Pulse-Wave Velocity in Mice with MRI at 17.6 T

Volker Herold¹, Marco Parczyk¹, Gert Klug², Wolfgang Rudolf Bauer², Peter Michael Jakob¹, Eberhard Rommel¹

¹Department of Experimental Physics 5, University of  Würzburg, Würzburg, Germany; ²Medizinische Universitätsklinik, University of  Würzburg, Würzburg, Germany

In this work we present two different methods to non-invasively examine the pulse-wave velocity (PWV) at different sites in the murine aorta: a regional multipoint-transit-time (TT) method and a local flow-area (QA) approach. MR experiments were validated with a deformable vessel wall phantom. The in vivo PWV values measured with the MR-technique showed good agreement with values stated in literature measured using Doppler ultrasound. While the multipoint TT-approach allows to assess local and regional PWV changes in the descending aorta, the local QA-approach is useful to detect early vascular abnormalities at locations such as the ascending aorta.

                  1860.     Simultaneous Angiography and Venography Techniques Compared at 7T

Samuel Barnes^1,2, Yulin Ge³, Lin Tang³, Zhongwei Zhang³, Daniel K. Sodickson³, Robert I. Grossman³, E. Mark Haacke²

¹Radiology, Loma Linda University, Loma Linda, CA, USA; ²Wayne State University, Detroit, MI, USA; ³New York University School of Medicine

Two techniques to acquire angiographic and venographic information with a single acquisition at 7T were compared: a single echo sequence and double echo sequence. The single echo sequence produced an excellent venography but suffered from some flow losses in the larger arteries due to the long echo time. The double echo sequence produced an excellent angiography and venography but took significantly longer than the single echo technique.

                  1861.     Single Echo Simultaneous Angiography and Venography (MRAV) Techniques at 3T

Samuel Barnes^1,2, E. Mark Haacke^1,2

¹Radiology, Loma Linda University, Loma Linda, CA, USA; ²Biomedical Engineering, Wayne State University, Detroit, MI, USA

Single echo techniques to acquire both angiography and venography information using susceptibility weighted imaging (SWI) usually require trade offs between the angiography and venography in the choice of echo time and flip angle. This work examines the role of bandwidth and resolution in reducing flow losses in the angiography while maintaining a long echo time for the venography. Two downsampling filters used to improve the quality of the venography are also examined.

                  1862.     Compatible Dual-Echo Arteriovenography (CODEA) Using an Echo-Specific K-Space Reordering Scheme

Sung-Hong Park^1,2, Chan-Hong Moon¹, Kyongtae Ty Bae^1,2

¹Radiology, University of Pittsburgh, Pittsburgh, PA, USA; ²Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA

Compatible dual-echo arteriovenography (CODEA) was developed to simultaneously acquire a time-of-flight MR angiogram (MRA) and a blood-oxygenation-level-dependent MR venogram (MRV) in a single acquisition at 3T. In this method, an echo-specific K-space reordering scheme was employed to uncouple the scan parameter requirements for the MRA and MRV. The MRA/MRV vascular contrast was enhanced by maximally separating the K-space center regions of the two echoes and by adjusting and applying scan parameters compatible between them. As a preliminary result, CODEA MRA/MRV could be acquired simultaneously with image quality comparable to that of the conventional single echo MRA/MRV separately acquired at two sessions.

                  1863.     Effective Application of Multiple Overlapping Thin-Slab Acquisition and Magnetization Transfer Contrast Pulse to Compatible Dual-Echo Arteriovenography (CODEA)

Sung-Hong Park^1,2, Chan-Hong Moon¹, Kyongtae Ty Bae^1,2

¹Radiology, University of Pittsburgh, Pittsburgh, PA, USA; ²Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA

MOTSA and MTC pulse were incorporated into a newly-introduced compatible dual-echo arteriovenography (CODEA) that was developed for simultaneous acquisition of TOF MRA and BOLD MRV. Both MRA and MRV acquired with the MOTSA-incorporated CODEA provided seamless vascular continuity over a large brain volume. The MTC pulse, applied only to K-space center region of the first echo, selectively suppressed the background tissue signal in the MRA, thus enhancing the arterial contrast, with little effect on the MRV. These results indicate that techniques commonly used in conventional TOF MRA such as MOTSA and MTC pulse are effectively applicable to the CODEA technique.

                  1864.     Compatible Dual-Echo Arteriovenography (CODEA) Imaging at 7T Versus 3T

Kyongtae Ty Bae^1,2, Sung-Hong Park^1,2, Chan-Hong Moon¹, Jung-Hwan Kim¹

¹Radiology, University of Pittsburgh, Pittsburgh, PA, USA; ²Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA

We have implemented and demonstrated markedly improved imaging of both time-of-flight (TOF) MR angiogram (MRA) and blood oxygenation level-dependent (BOLD) MR venogram (MRV) at 7T that were acquired simultaneously using a newly developed compatible dual-echo arteriovenography (CODEA) technique, in comparison with the CODEA MRA/MRV at 3T. Preliminary results indicate imaging at the higher-field allows improved visualization of small vessels in MRA and MRV due to greatly increased signal-to-noise ratio (SNR) and susceptibility contrast.

                  1865.     View Sharing in Slice Direction for Continuously Moving Table Acquisitions: Application to TOF Venography

Sandra Huff¹, Matthias Honal², Michael Markl², Ute Ludwig²

¹Department of Diagnostic Radiology, Medical Physics , University Hospital Freiburg, Freiburg, Germany; ²Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany

For increasing temporal resolution in MRI, several view sharing (VS) techniques have been developed where high spatial frequencies are not sampled for all time frames and data from the different time frames are combined. In this study the VS concept was applied to share data between different slice positions for axial continuously moving table (CMT) acquisitions. By varying the patient table velocity the degree of VS could be flexibly adjusted. The feasibility of CMT VS was tested for the application to CMT Time-of-Flight venography of the peripheral vessels.

                  1866.     Acute Renal Effect Following 0.1 Mmol/kg OMNISCAN„  (Gadodiamide Injection) Administration for Magnetic Resonance Angiography (MRA) of the Renal Arteries

Vesna D. Garovic¹, Manuela Aschauer², Thomas Kittner³, International Investigator team SOV301 Investigators⁴

¹Nephrology, Mayo Clinic, Rochester, MN, USA; ²Universitätsklinikum , Graz, Austria; ³Institut und Poliklinik für Röntgendiagnostik, Dresden, Germany; ⁴International multicenter trial

In a multicenter, international, controlled study of Omniscan (gadodiamide)-enhanced MRA for evaluation of patients with suspected or known renal artery stenosis, renal function was assessed as part of overall safety monitoring. This report is to present potential acute effect of Omniscan administration on kidney function. Single dose administration of 0.1 mmol/kg Omniscan for contrast-enhanced MRA of renal arteries for detection of renal artery stenosis has minimal impact on patients¡¯ kidney function. No difference was seen in contrast-induced nephrotoxicity or adverse event rates between patients with baseline GFR <60 and those ¡Ý60 mL/min/1.73 m2.

                  1867.     Pre-Operative Localization of the Artery of Adamkiewicz Using Time-Resolved Magnetic Resonance Angiography at 3.0T

Cory Christopher Duffek¹, Thorsten A. Bley^1,2, Christopher J. Francois¹, Mark L. Schiebler¹, Matthew Mell³, Thomas Grist^1,4, Scott B. Reeder¹

¹Radiology, University of Wisconsin, Madison, WI, USA; ²Radiology, University of Freiburg, Freiburg, Germany; ³Surgery, University of Wisconsin, Madison, WI, USA; ⁴Medical Physics, University of Wisconsin, Madison, WI, USA

Increasingly, data suggest that preservation of the artery of Adamkiewicz (AKA) through reimplantation of intercostal/lumbar arteries at the time of thoracoabdominal and thoracic aortic aneurysm repair plays a key role in the prevention of spinal cord ischemia and paralysis. The purpose of this work is to use time-resolved contrast-enhanced magnetic resonance angiography (TR-MRA) to localize the AKA prior to surgical reimplantation. A retrospective study was performed in 60 patients who underwent pre-operative TR-MRA at 3.0T. The AKA was accurately localized in 88% of cases. TR-MRA at 3.0T is an effective method for presurgical localization of the AKA.

                  1868.     Gadofosveset Trisodium-Enhanced Steady State Free Precession Magnetic Resonance Angiography of Left Atrium and Pulmonary Veins

Moritz Wagner¹, Patick Asbach¹, Alexander Huppertz², Matthias Taupitz¹, Carsten Warmuth¹, Bernd Hamm¹, Alexander Lembcke¹

¹Radiology, Charité, Universitätsmedizin Berlin, Berlin, Germany; ²Imaging Science Institute Charité Berlin - Siemens, Berlin, Germany

Due to the complex anatomy preprocedual imaging is frequently performed before catheter intervention for pulmonary vein isolation. With the advent of electrocardiogram-gated and respiratory-gated 3D steady state free precession sequences covering the entire heart (whole-heart MR angiography) it has become possible to visualize cardiac vascular anatomy with high spatial resulution using MR imaging. The hypothesis for this study was that the intravascular contrast medium gadofosveset trisodium improves image quality of whole-heart MR angiography and hereby allows excellent visualisation of left atrium and pulmonary veins.

                  1869.     On the Amenability of Ghost Imaging to Large Parallel Acceleration Factors

Ioannis Koktzoglou¹, Robert R. Edelman¹

¹Department of Radiology, NorthShore University HealthSystem, Evanston, IL, USA

Ghost imaging is a newly proposed methodology for angiography that does not use image subtraction and depends on the presence of arterial ghost artifacts outside of the body. Presumably due to the sparsity of these ghost artifacts and the absence of background signal, the method is found to better support the use of higher parallel acceleration factors than does conventional subtraction-based MRA.

                  1870.     Inflow-Sensitive Inversion Recovery SSFP Imaging of the Carotid Arteries: A Potential Strategy for Noncontrast MRA of the Neck

Phillip Young¹, Mohammad-Mehdi Khalighi², Anja Brau, Naoyuki Takei³, Wei Sun⁴, Robert Herfkens⁵

¹Radiology, Stanford University, Stanford, CA, USA; ²Applied Science Laboratory West, GE Healthcare, Menlo Park, CA, USA; ³Applied Science Laboratory Japan, GE Healthcare, Tokyo, Japan; ⁴MR Engineering, GE Healthcare, Waukesha, WI, USA; ⁵Radiology, Stanford University, Palo Alto, CA, USA

We describe our initial experience with inversion-prepared balanced SSFP imaging of the carotid and vertebral arteries in 9 healthy volunteers. While the extent of coverage achieved was not sufficient to image from the aortic arch to the skull base in a single acquisition, the images provided excellent visualization of the carotid and vertebral arteries and their branches. In all but one patient, 6 or 7 of the usual 8 branches of the external carotid arteries were seen for at least 2 cm. Further work is needed to assess utility of the sequence in clinical patients, particularly in comparison to currently used methods.

                  1871.     Comparison of Non-Contrast In-Flow Inversion Recovery (Inhance) Steady State Free Precession Renal MRA at 1.5T and 3T

David W. Stanley¹, James F. Glockner², Naoki Takahashi², Steven L. Williams², Marilyn R. Wood², Naoyuki Takei³, Sun Wei⁴

¹GE Healthcare, Proctor, MN, USA; ²Mayo Clinic, Rochester, MN, USA; ³Applied Science Laboratory Japan, GE Yokogawa Medical Systems, Hino, Tokyo, Japan; ⁴MR Engineering, GE Healthcare, Waukesha, WI, USA

CE-MRA is accepted technique for evaluation of the renal arteries; however, recent concerns regarding the development of nephrogenic systemic fibrosis after gadolinium contrast agent administration in patients with reduced renal function have emphasized the need for non-contrast MRA methods. One such technique is SSFP with in-flow inversion recovery (Inhance). Inhance has produced accurate and reliable images of the renal arteries in a variety of patients at 1.5T. Inhance at 3T offers potential advantages (improved SNR) and limitations (increased image artifact). We compared image quality and diagnostic accuracy of Inhance at 1.5T and 3T in a series of volunteers and patients.

                  1872.     Analysis of Renal Artery  Motion During Free Breathing

Ashley Gould Anderson III¹, Kevin M. Johnson¹, Oliver Wieben^1,2

¹Medical Physics, University of Wisconsin, Madison, WI, USA; ²Radiology, University of Wisconsin, Madison, WI, USA

Motion of the proximal and distal left and right renal arteries of five volunteers was characterized for the complete respiratory cycle during free breathing. The resulting data provided useful information for respiratory gated acquisitions in renal MRA that use motion measures such as a navigator or bellow reading. With a 40% data acceptance threshold, motion in the renal arteries was limited to 3 mm or less in all subjects. This threshold is the ‘sweet spot’ for limiting renal artery motion to displacements encountered from cardiac pulsatility while keeping the penalties in scan time reasonable.

                  1873.     Non-Contrast MR Angiography of the Renal Arteries:  Improvements in Vessel Length and SNR with Multiple Heartbeat Inflow Period

Steven M. Shea¹, Seth J. Berkowitz², Jens Vogel-Claussen², Aravind Arepally², Peter Weale³, Xiaoming Bi³, Christine H. Lorenz¹, David A. Bluemke⁴

¹Imaging and Visualization, Siemens Corporate Research, Inc, Baltimore, MD, USA; ²Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD, USA; ³Siemens Medical Solutions USA, Chicago, IL, USA; ⁴Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, USA

Blood flow in the kidneys is reduced in patients with renal failure, which hampers vascular visualization with sel-IR-SSFP non-contrast MRA. To improve vessel length and image quality, we proposed to increase inversion time so that two aortic pulse waves would occur between inversion and data acquisition. This protocol was compared with the standard single heartbeat approach in 20 patients with renal failure. Vessel length, SNR, and image quality was significantly better for the two heartbeat approach. This enables visualization of second and third orders branches, which is important for identifying distal stenosis, planning percutanous procedures, and screening for incidental aneurysms.

                  1874.     Unenhanced 3D Ghost MR Angiography by Toggled Systolic and Diastolic Imaging

Ioannis Koktzoglou¹, Robert R. Edelman¹

¹Department of Radiology, NorthShore University HealthSystem, Evanston, IL, USA

Ghost magnetic resonance angiography (MRA) is a new method for unenhanced and enhanced angiography that is predicated on ghost artifacts and does not use signal subtraction. We show that 3D unenhanced Ghost MRA can be performed by triggering the acquisition of every other slice-encoding step to systole and the remaining steps to diastole. When applied to the peripheral arteries, the 3D Ghost MRA method was found to perform better than a conventional subtraction-based unenhanced MRA method.

                  1875.     Non-Contrast Enhanced Renal Angiography Using Multiple Inversion Recovery and Steady-State Free Precession

Hattie Zhi Chen Dong¹, Holden H. Wu¹, Dwight G. Nishimura¹

¹Electrical Engineering, Stanford University, Stanford, CA, USA

We investigate the use of multiple inversion recovery suppression with 3D balanced SSFP (MIR SSFP) to provide high contrast in renal non-contrast enhanced MR angiography. The MIR preparation segment uses several nonselective inversions to concurrently suppress a broad range of background tissues, while allowing inflowing blood to maintain its longitudinal magnetization. The length of the SSFP imaging train was adjusted to trade off between static tissue nulling level and scan time. Results are compared with balanced SSFP without any magnetization preparation, and slab-selective single inversion SSFP.

                  1876.     The Mathematics of HYPR

Angel Ramon Pineda¹, Atousa Sarcon¹, Nasser Abbasi¹, Doug Stang¹, Siavash Jalal¹, Kacie Jacklin¹, Reed F. Busse², Jean H. Brittain²

¹Mathematics Department, California State University, Fullerton, CA, USA; ²Applied Science Laboratory, GE Healthcare, Madison, WI, USA

HYPR is a promising new method for time-resolved imaging that uses a time averaged image (composite) to improve images at individual time frames. We show that HYPR and a subsequently described modification by Huang and Wright (HW-HYPR) can be understood mathematically as the first step of iterative methods used in other imaging modalities: HYPR as an approximation to maximum likelihood expectation maximization (MLEM) and HW-HYPR as the multiplicative arithmetic reconstruction technique (MART) used to solve the normal equations, where the composite image serves as an initial estimate prior to iteration.

                  1877.     Refocused Turbo Spin Echo for Noncontrast MRA

Samuel W. Fielden¹, John P. Mugler III^1,2, Klaus D. Hagspiel², Christopher M. Kramer^2,3, Craig H. Meyer^1,2

¹Biomedical Engineering, University of Virginia, Charlottesville, VA, USA; ²Department of Radiology, University of Virginia, Charlottesville, VA, USA; ³Department of Medicine, University of Virginia, Charlottesville, VA, USA

A refocused Turbo Spin Echo (rTSE) technique for nonconcrast MRA is presented. rTSE hybridizes the increased signal provided by the 180° refocusing RF pulses of RARE and the better flow performance of the fully-refocused gradients and phase alternation of balanced SSFP. Angiograms generated by the rTSE sequence are compared to those generated by a traditional TSE sequence and exhibits higher contrast resolution and vessel sharpness (p < 0.01) with comparable SNR.

                  1878.     NATIVE SPACE Angiography with MTC and Fat Saturation Pulses

Agus Priatna¹, Glenn Foster², Jian Xu¹, Peter Weale¹, Scott Love², Vamsi Narra²

¹R&D Collaborations, Siemens Medical Solutions USA, Malvern, PA, USA; ²Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO, USA

Recently, a novel technique using triggered non-selective refocused 3D SPACE or called NATIVE SPACE was shown to improve spatial resolution and speed. In this abstract, we propose to use magnetization transfer pulse and fat saturation pulses to help suppress the background tissue and fat signal to further improve the images of the vessels after subtractions.

                  1879.     Continuously Moving Table Time-Of-Flight Angiography of the Peripheral Veins

Sandra Huff¹, Matthias Honal¹, Tobias Baumann², Jürgen Hennig¹, Michael Markl¹, Ute Ludwig¹

¹Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany; ²Department of Diagnostic Radiology, University Hospital Freiburg, Freiburg, Germany

To overcome the limited volumetric coverage of standard Time-of-Flight (TOF) techniques, the aim of this study was to investigate the combination of TOF and Continuously Moving Table (CMT) acquisitions for peripheral vein imaging based on image subtraction. Two acquisition strategies are presented: A 2-step method with two-fold CMT acquisition and an advanced 1-step method with an interleaved arrangement of imaging and saturation slices requiring only one continuous scan. Image quality was evaluated by semi-quantitative image grading and by SNR and CNR analysis for peripheral veins in healthy volunteers. Results were compared to a standard stationary 2D TOF multistation acquisition.

                  1880.     Non-Contrast Abdominal Angiography Using Continuous Arterial Spin Labeling and Background Suppression

Philip M. Robson¹, Weiying Dai¹, Ajit Shankaranarayanan², David C. Alsop¹

¹Radiology, Beth Israel Deaconess Medical Center, Boston, MA, USA; ²Applied Science Laboratory, GE Healthcare, Menlo Park, CA, USA

Pulsed Arterial Spin Labelling (ASL) techniques applied to abdominal angiography often require a complex optimization of inversion time because it influences background intensity, sensitivity, and robustness to delayed or slow inflow. We used continuous ASL combined with background suppression to obtain subtraction angiograms of the body with low background, high sensitivity, and robustness to delayed arterial arrival. Large field of view angiograms were obtained which clearly show the major vessels, including the renal arteries, and many branching vessels. Focused on the kidneys, angiograms suitable for the assessment of renal artery stenoses were obtained.

                  1881.     Non-Contrast-Enhanced MRA of the Renal Arteries Using Inflow-Enhanced, Inversion-Recovery BSSFP: Validation Against DSA in a Porcine Model of Renal Artery Stenosis

Thorsten Alexander Bley¹, Christopher Jean Pierre Francois¹, Mark L. Schiebler¹, Oliver Wieben², Naoyuki Takei³, Wei Sun⁴, Mitsuharu Miyoshi³, Jean H. Brittain⁴, Reed F. Busse⁴, Thomas M. Grist¹, Scott B. Reeder¹

¹Radiology, University of Wisconsin - Madison, Madison, WI, USA; ²Radiology and Medical Physics, University of Wisconsin - Madison, Madison, WI, USA; ³MR Applied Sciences Laboratory, GE Healthcare, Tokyo, Japan; ⁴MR Applied Sciences Laboratory, GE Healthcare, Waukesha, WI, USA

This study evaluates an investigational version of the Inhance Inflow IR pulse sequence, a balanced SSFP (bSSFP) based NCE-MRA sequence that is combined with the inflow effects of time of flight MRA for detection and quantification of renal artery stenoses, in a porcine model. Results of three readers who evaluated the degree of surgically created renal artery stenosis in 12 swine were compared to 3D rotational DSA. The NCE-MRA technique produced consistent results, with no technical failures. Good correlation between NCE-MRA and DSA demonstrates the feasibility of this NCE-MRA sequence for assessment of renal artery stenoses.

                  1882.     Flow-Independent, Non-Contrast-Enhanced, Free Breathing Renal MR Angiography

Gregory J. Wilson^1,2, George R. Oliveira², Jeffrey H. Maki^2,3

¹MR Clinical Science, Philips Healthcare, Cleveland, OH, USA; ²Radiology, University of Washington, Seattle, WA, USA; ³Radiology, Puget Sound VAHCS, Seattle, WA, USA

A flow-independent renal MRA sequence was implemented and evaluated. The sequence uses ECG-triggering and respiratory navigator gating to minimize motion artifacts and acquire during slow flow (diastole). The 3D acquisition uses spectral fat saturation (SPIR), T2-Prep, and Bal-TFE readout with radial low-high profile order. Flow-independence is demonstrated by uniform blood signal intensity in coronal acquisitions and minimal effect of in-flow saturation slabs. Three healthy volunteers were imaged with excellent image quality. The flow-independent sequence will be used in patients with suspected renal artery stenosis to better depict morphology distal to stenoses.

                  1883.     Fat Suppression for Non-Contrast-Enhanced Peripheral Angiography: Phase-Sensitive Versus IDEAL SSFP

Tolga Çukur¹, Ann Shimakawa², Huanzhou Yu², Brian A. Hargreaves¹, Bob S. Hu³, Jean H. Brittain², Dwight G. Nishimura¹

¹Stanford University, Stanford, CA, USA; ²Applied Science Laboratory, GE Healthcare, USA; ³Palo Alto Medical Foundation, USA

High-resolution non-contrast-enhanced peripheral angiograms can be produced with magnetization-prepared SSFP sequences. However, reliable fat suppression is crucial for this application due to the inherently bright fat signal. To reduce the sensitivity to field inhomogeneity over large FOVs (e.g., imaging both limbs), we have investigated two fat/water separation techniques compatible with dual-acquisition complex-sum SSFP. The simple phase-sensitive reconstruction achieves a shorter TR and scan time, but suffers from partial volume artifacts that reduce the visibility of small vessels. On the other hand, IDEAL enhances the small vessel depiction and yields better venous suppression due to its longer TR.

                  1884.     Non-Contrast Enhanced MRA Using Inhance Inflow IR with 3D FRFSE for Carotid Artery Imaging

Naoyuki Takei¹, Mitsuharu Miyoshi¹, Tetsuji Tsukamoto¹

¹GE Yokogawa Medical Systems.Ltd, Hino, Tokyo, Japan

A new non-contrast enhanced MR angiography was proposed. Inhance Inflow IR is a method to depict blood flow employing inversion recovery pulse to suppress background tissues on imaging volume and move unsaturated flowing blood spins into the volume. The fully recovered blood magnetization in equilibrium state and elaborated background suppression technique with multiple inversion pulses provide high contrast ratio between arterial blood and background tissues. To demonstrate this presented technique feasible, comparison study with conventional TOF MRA were performed using an investigational version of the Inhance Inflow IR in healthy volunteers. The comparable results on vessel depiction of entire carotid arteries were obtained.