Tobias Speidel¹, Patrick Metze², Fabian Straubmueller², Hao Li¹, and Volker Rasche^2
1Core-Facility Small Animal Imaging, Ulm University, Ulm, Germany, ²Experimental Cardiovascular MRI, Ulm University Medical Center, Ulm, Germany

The application of self-gating techniques to small animal imaging poses challenging problems, particularly dominated by the high respiratory frequencies. Established self-gating methods are based on information that is extracted either from the k-space itself or from low-resolution images, leading to one-dimensional gating signals. These approaches are prone to fail in the case of arrhythmic respiratory and/or cardiac motion. The concept of nonuniform self-gating is capable of retrospectively considering respiratory and cardiac motion despite significant changes in cardiac or respiratory frequencies by using a two-dimensional gating matrix for deriving the required gating information.

Camila Munoz¹, Iain Sim², Aurelien Bustin¹, Radhouene Neji^1,3, Karl P Kunze³, Michaela Schmidt⁴, Mark O’Neill², Steven E Williams², Rene M Botnar¹, and Claudia Prieto^1
1Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ²Cardiovascular Imaging Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ³MR Research Collaborations, Siemens Healthcare Limited, Frimley, United Kingdom, ⁴Cardiovascular MR Predevelopment, Siemens Healthcare GmbH, Erlangen, Germany

3D late gadolinium enhanced (LGE) imaging is a promising technique for the non-invasive assessment of atrial fibrosis. In order to minimize respiratory motion, current 3D LGE atrial imaging relies on diaphragmatic navigator gating, leading to time-consuming scans with unpredictable duration. Here we introduce a highly efficient respiratory motion-compensated 3D water/fat IR-prepared LGE atrial imaging protocol with predictable scan time. Preliminary results demonstrate that the proposed approach enables depiction of atrial scar comparable to conventional 3D atrial LGE imaging, but with a significantly shorter scan time of <5 minutes. The proposed approach holds promise for high-resolution atrial wall imaging.

Grzegorz Kwiatkowski¹, Frank Kober², and Sebastian Kozerke^1
1Institute for Biomedical Engineering, ETH Zurich, Zurich, Switzerland, ²Aix Marseille Univ, CNRS, CRMBM, Marseille, France

The feasibility of accelerating arterial spin labelling (ASL) by exploiting spatiotemporal correlations for assessing myocardial perfusion in small animals is demonstrated. Based on numerical simulations and retrospectively undersampled in-vivo data, three-fold acceleration yields errors below 16 ± 10 % in myocardial blood flow quantification and hence the method is considered promising to shorten the long scan times of myocardial ASL in small animals.

Mark Gosselink¹, Hugo Klarenberg², Hildo J. Lamb³, Gustav J. Strijkers², Dennis W.J. Klomp¹, Tim Leiner¹, and Martijn Froeling^1
1University Medical Center Utrecht, Utrecht, Netherlands, ²Amsterdam University Medical Center, Amsterdam, Netherlands, ³Leiden University Medical Center, Leiden, Netherlands

Cardiac triggered CINE imaging is used clinically for the assessment of cardiac function. The purpose of this study is to investigate the feasibility of real time free breathing CINE MRI using a high density receive array on a 3T clinical system with online compressed SENSE image reconstruction. We demonstrate feasibility of real-time 2D CINE imaging using a high-density coil array.

Lukas Braunstorfer¹, Mehdi H. Moghari², and Andrew H. Powell^3
1Cardiology, Harvard Medical School, cambridge, MA, United States, ²Cardiology, Harvard Medical School, boston, MA, United States, ³Cardiology, Harvard Medical School, Boston, MA, United States

Free-breathing 3D cine steady-state free precession (SSFP) sequence with radial phyllotaxis trajectory is recently performed for making cardiac magnetic resonance imaging (MRI) exams easy and more comfortable for patients. Phyllotaxis trajectory is susceptible to the eddy current artifact due to a large gradient change during the 3D cine SSFP acquisition for measuring the centerline of k-space. We, therefore, developed and validated a novel leaf trajectory that minimizes the gradient change, and eddy current.

Christopher Nguyen^1,2,3, Timothy G Reese^3,4, Congyu Liao^3,4, William J Kostis⁵, Marcel P Jackowski⁶, Kawin Setsompop^3,4, and Choukri Mekkaoui^3,4
1Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, United States, ²Department of Medicine, Harvard Medical School, Boston, MA, United States, ³Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ⁴Department of Radiology, Harvard Medical School, Boston, MA, United States, ⁵Cardiovascular Institute, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States, ⁶Department of Computer Science, University of São Paulo, São Paulo, Brazil

Free-breathing isotropic cardiac diffusion tensor MRI (DT-MRI) of the left ventricle can be performed using second moment (M2) motion compensated spin echo encoding and generalized slice dithered enhanced resolution (gSlider). This technique provides substantial improvements in spatial resolution and consequently in the accuracy of diffusion-based indices. However, M2-gSlider’s RF slice encoding is susceptible to through-slice motion, limiting the maximal improvement in slice resolution.  Here, we evaluate the addition of a slice tracking respiratory navigator (NAV) to prospectively adjust slice position in real-time. M2-gSlider-NAV was validated in healthy volunteers and tested in a patient with a history of myocardial infarction.

Guruprasad Krishnamoorthy^1,2, Joao Silva Tourais^1,2, Jouke Smink¹, Marc Kouwenhoven¹, and Marcel Breeuwer^1,2
1Philips Healthcare, Best, Netherlands, ²Eindhoven University of Technology, Eindhoven, Netherlands

The benefits of the current cardiac CINE MRI are often limited by the requirement of patient co-operation for multiple breath-holds. To overcome this limitation, we present a new, free-breathing respiratory motion-compensated 2D multi-slice radial CINE method for left ventricular functional assessment. Our method utilizes the respiratory signal obtained from a patient sensing camera for performing motion weighted density compensation in radial gridding to minimize respiratory motion artifacts in the reconstructed image. The left-ventricular functional assessments from volunteers obtained using the proposed method are in good agreement with the results obtained using the standard Cartesian breath-hold method.

Giorgia Milotta¹, Aurelien Bustin¹, Olivier Jaubert¹, Radhouene Neji¹, Claudia Prieto¹, and Rene Botnar^1
1Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom

Tissue characterization including identification and quantification of fibrosis and oedema plays an important role in many myocardial diseases. Conventionally 2D T₁ and T₂ maps are acquired sequentially under several breath-holds. However these approaches achieve limited spatial resolution and coverage. Furthermore, partial volume effects at water-fat interfaces may affect T₁ and T₂ quantification. In this work, we propose a free-breathing high-resolution whole-heart joint T₁ and T₂ mapping sequence with Dixon encoding which provides co-registered 3D T₁ and T₂ maps and complementary 3D anatomical water coronary magnetic resonance angiography (CMRA) and fat images in a single scan of ~9min.

Maaike van den Boomen^1,2, Mary Kate Manhard^1,3, Kyrre E. Emblem⁴, David E. Sosnovik^1,5,6, Niek H.J. Prakken², Christopher Nguyen^1,5,6, Kawin Setsompop^1,3,7, and Ronald J.H. Borra^2,8
1A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, ²Department of Radiology, University Medical Center Groningen, Groningen, Netherlands, ³Department of Radiology, Harvard Medical School, Boston, MA, United States, ⁴Department of Diagnostic Physics, Oslo University Hospital, Oslo, Norway, ⁵Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA, United States, ⁶Department of Medicine, Harvard Medical School, Boston, MA, United States, ⁷Division of Health Sciences and Technology, Harvard-MIT, Cambridge, MA, United States, ⁸Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, Groningen, Netherlands

Vessel architectural imaging (VAI) is explored in the heart by using a heartbeat-to-heartbeat GESE-EPI sequence upon injection of Gd-DTPA. Cardiac VAI can provide the vascular type, caliber, density and blood volume fraction indices in the myocardium, in line with previous work performed in the brain. Further histological validation of these indices is needed, but our initial results demonstrates the feasibility of this technique to advance cardiovascular research into cardiac microvascular dysfunction.  

Cian Michael Scannell¹, Adriana Villa¹, Stefano Figliozzi¹, Jack Lee¹, Mikto Veta², Marcel Breeuwer^2,3, and Amedeo Chiribiri^1
1King's College London, London, United Kingdom, ²Eindhoven University of Technology, Eindhoven, Netherlands, ³Philips Healthcare, Best, Netherlands

Quantitative myocardial perfusion MRI has the potential to guide the management of patients with coronary artery disease. It has been shown to have high prognostic value and has the benefit of being automated and user-independent. However, a known limitation of the technique is that it cannot distinguish between perfusion defects that are due to a previous infarction and inducible ischemia. In this work we combine quantitative myocardial perfusion with a further automated pipeline for scar quantification from LGE images. It is shown that this combined assessment can identify areas of inducible ischemia in which the tissue is viable.

Changyu Sun¹, Austin Robinson², Christopher Schumann², Daniel Weller^1,3, Michael Salerno^1,2,4, and Frederick Epstein^1,4
1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States, ²Medicine, University of Virginia, Charlottesville, VA, United States, ³Electrical and Computer Engineering, University of Virginia, Charlottesville, VA, United States, ⁴Radiology, University of Virginia, Charlottesville, VA, United States

Multiband (MB) excitation and in-plane acceleration of first-pass perfusion imaging has the potential to provide a high aggregate acceleration rate. Our recent slice-SPIRiT work formulated MB reconstruction as a constrained optimization problem that jointly uses in-plane and through-plane coil information and MB data consistency. Here we extend these methods to develop k-t slice-SPARSE-SENSE and k-t slice-L+S reconstruction models. First-pass perfusion data with MB=3 and rate-2 k-t Poisson-disk undersampling were acquired in 6 patients. The slice-L+S reconstruction showed sharper borders and greater contrast than slice-SPARSE-SENSE and had better image quality scores as assessed by two cardiologists.

Julian A. J. Richter^1,2, Tobias Wech¹, Andreas M. Weng¹, Manuel Stich^1,3, Ning Jin⁴, Thorsten A. Bley¹, and Herbert Köstler^1
1Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany, ²Comprehensive Heart Failure Center Würzburg, Würzburg, Germany, ³Siemens Healthcare, Erlangen, Germany, ⁴Siemens Medical Solutions USA, Inc., Chicago, IL, United States

The wave-CAIPI technique was applied to aortic 4D flow MRI. Three healthy volunteers were examined and flow parameters as well as hemodynamic flow patterns were derived from the measured data. The acquisitions were retrospectively accelerated and compared to conventional Cartesian 2D-CAIPI sampling. Using wave-CAIPI sampling, the deviations between flow parameters of the 6-fold accelerated scans and the references (2-fold accelerated) could be reduced by up to 47% compared to Cartesian sampling. As a consequence, the acquisition time of aortic 4D flow acquisitions could be decreased to 3.5 minutes with higher precision, concerning the calculated flow parameters and hemodynamic flow patterns.

Ioannis Koktzoglou^1,2, Rong Huang¹, Pascale J Aouad^1,3, Emily A Aherne^1,3, Archie L Ong^2,4, and Robert R Edelman^1,3
1Radiology, NorthShore University HealthSystem, Evanston, IL, United States, ²The University of Chicago Pritzker School of Medicine, Chicago, IL, United States, ³Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States, ⁴Neurology, NorthShore University HealthSystem, Evanston, IL, United States

Ungated quiescent-interval slice-selective (QISS)-based magnetic resonance angiography (MRA) of the extracranial carotid arteries normally carries scan times of approximately 7 minutes. This work evaluated the feasibility of 3-fold accelerated single-shot QISS MRA in under three minutes using radial k-space sampling and a patch-based deep learning image reconstructive strategy.

Peng Lai¹, Christopher M Sandino², Shreyas S Vasanawala³, Anne Menini¹, Haonan Wang⁴, Anja C.S Brau¹, and Martin A Janich^5
1GE Healthcare, Menlo Park, CA, United States, ²Electrical Engineering, Stanford University, Palo Alto, CA, United States, ³Radiology, Stanford University, Palo Alto, CA, United States, ⁴GE Healthcare, Waukesha, WI, United States, ⁵GE Healthcare, Munich, Germany

Valvular imaging is challenging to conventional cine MRI due to its requirement of very high spatial and temporal resolution. This work preliminarily investigated valvular cine MRI with highly accelerated data acquisition powered by deep learning reconstruction. Our results demonstrated the feasibility to resolve valve anatomy and motion with nearly 1mm spatial resolution and 10ms frame rate, while flow-induced dephasing generates shading in blood pool and can complicate valve visualization.