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Lan Ge¹, Aya Kino¹, Natasha Berg¹, Xin Liu¹, Nicole Mascheri¹, Mark Griswold², Andrew Larson¹, Charles Mistretta³, James Carr¹, Debiao Li¹

¹Northwestern University, Chicago, Illinois, USA; ²Case Western Reserve University, USA; ³University of Wisconsin-Madison, Madison, Wisconsin, USA

Image quality and slice coverage for myocardial perfusion MRI are limited by the temporal resolution of current approaches. This work demonstrated the feasibility of sliding CG-HYPR for accelerated myocardial perfusion imaging with a temporal resolution of one time frame per cardiac cycle. Using this method, the acquisition time per cardiac cycle was reduced dramatically, which allows increasing the number of slices for myocardial perfusion imaging and reducing motion artifacts. The signal changes of left ventricle and myocardium were verified by the comparison to conventional methods. Mean correlation coefficients between sliding CG-HYPR and reference images are 0.9672, 0.9423 for blood and myocardial signals, respectively.

Bernd André Jung¹, Matthias Honal¹, Jürgen Hennig¹, Michael Markl¹

¹University Hospital, Freiburg, Germany

Dynamic first-pass contrast-enhanced myocardial perfusion MRI is an important clinical tool that greatly benefits from acceleration in data acquisition in terms of spatial resolution or number of slices to acquire per heartbeat. Advanced dynamic parallel imaging techniques have been introduced such as k-t-SENSE and k-t-BLAST, k-t-GRAPPA, and PEAK-GRAPPA as an extension of k-t-GRAPPA to reduce total acquisition time or to increase spatiotemporal resolution. In a study with 11 patients an application of a k-t-space related GRAPPA technique to myocardial perfusion as non-periodic motion has been investigated.

Hui Xue¹, ², Jens Guehring², Jo V. Hajnal¹, Daniel Rueckert, Sven Zuehlsdorff³, Kinda Saddi², Christophe Chefdhotel²

¹Hammersmith Hospital, Imperial College London, London, UK; ²Siemens Corporate Research, Princeton, New Jersey, USA; ³Siemens Medical Solutions USA, Inc., Chicago, USA

Myocardial Perfusion MRI can be undermined by subject motion, which makes sequences of images acquired during contrast uptake inconsistent. In this work, the performance of rigid and non-rigid motion compensation techniques is evaluated on a multi-center perfusion dataset containing more than 500 individual time series, obtained under clinically relevant conditions.The results confirm that motion correction is a frequent requirement (67% of cases in this sample). The registration based methods we developed were found to be effective in 98.5% of the cases tested.

Pedro Ferreira¹, Peter Gatehouse², David Firmin¹, ², Chiara Bucciarelli-Ducci¹, ², Ricardo Wage²

¹Imperial College, London, UK; ²Royal Brompton Hospital, UK

Myocardial perfusion studies are often affected by the dark rim artifact, which mimics an under-perfused region. One of the possible origins pointed out in literature for this artifact is field distortion. In this work field distortions were measured during first pass of Gd-DTPA in the heart for 10 patients and compared to both phantom work and numerical simulations, which were found to agree well with the in-vivo data. Field distortions happen mainly in the myocardium wall, especially for more horizontal hearts, but appear to be too weak to cause any loss of signal.

Mao-Yuan Su¹, ², Bai-Chien Lee³, Yen-Wen Wu³, Hsi-Yu Yu², Woei-Chyn Chu⁴, Wen-Yih Isaac Tseng⁵, ⁶

¹National Yang-Ming University, Taipei, Taiwan; ²National Taiwan University Hospital, taipei, Taiwan; ³National Taiwan University Hospital, Taipei, Taiwan; ⁴National Yang-Ming University, taipei, Taiwan; ⁵College of Medicine, National Taiwan University, Taipei, Taiwan; ⁶national Taiwan University Hospital, taipei, Taiwan

Left ventricular (LV) remodeling after acute myocardial infarction (AMI) is known to be associated with the size of the infarct myocardium. It has been reported that residual viable myocardium within the infarct zone plays a protective role against LV remodeling and is one of major determinants of regional functional recovery after AMI. In this study, we aimed to assess the microvascular function of the residual viable myocardium by using cardiovascular magnetic resonance (CMR) imaging to delineate the residual viable myocardium and quantify myocardial blood flow (MBF). Our results suggested that the microvascular function was generally impaired in the reperfused infarct zone, but more viability salvaged could preserve more microvascular function.

Rohan Dharmakumar¹, Jordin D. Green², Jacqueline Flewitt³, Matthias Voehringer³, Neil G. Filipchuk³, Debiao Li¹, ⁴, Matthias G. Friedrich³

¹Northwestern University, Chicago, Illinois, USA; ²Siemens Medical Solutions, Calgary, Canada; ³University of Calgary, Calgary, Canada; ⁴Evanston, Illinois, USA

Oxygen-sensitive myocardial imaging may be an alternative to first-pass perfusion methods. This workdemonstrates that SSFP-based BOLD MRI can detect regional myocardial perfusion deficits in patientswith coronary artery disease.

Benjamin Richard Knowles¹, Phillip G. Batchelor², Victoria Parish¹, Mathew Ginks², Stephen Sinclair¹, Sven Plein³, Reza Razavi², Tobias Schaeffter²

¹King's College London, London, UK; ²King's College London, UK; ³University of Leeds, Leeds, UK

Standard myocardial perfusion imaging in the myocardium uses a two compartmental model to quantify the related pharmacokinetic parameters; however, an accurate quantification of pharmacokinetics in areas of late enhancing myocardium requires the addition of a third compartment. We report the first use of such a model to describe the uptake of contrast agent in myocardial infarctions. We fitted a three compartment model to data from images acquired 1-20 minutes post contrast agent administration. Initial results show that this model successfully describes late enhancement and could potentially to be a valuable tool for the quantification of myocardial late enhancement

Kyle Stephan McCommis¹, Haosen Zhang¹, Robert J. Gropler¹, Jie Zheng¹

¹Washington University School of Medicine, St. Louis, Missouri, USA

A cardiac MR method is demonstrated to quantify the regional myocardial oxygen consumption rate during hyperemia, by using the Fick’s principle. MRI data acquisition was performed in normal dogs, as well as dogs with a single vessel coronary stenosis. Each study session consisted of imaging at rest and pharmacologically-induced hyperemia. In normal dogs and normal myocardial regions of stenotic dogs, myocardial oxygen consumption rose similarly from the rest condition. However, the coronary artery stenosis attenuates the effect of hyperemia on the stenosis subtended region, which agrees well with other reports with human patients of coronary artery stenosis.

Christian Stehning¹, Victoria Parish², Stephen Sinclair², Eike Nagel², Hannes Dahnke¹, Tobias Schaeffter²

¹Philips Research, Hamburg, Germany; ²King's College, London, UK

We present a T1 mapping method allowing the quantification of contrast agent concentrations in infarcted myocardium is presented. A submillimeter spatial resolution allows to differentiate different infarct territories. The acquisition is performed during free breathing.

David Maintz¹, Murat Özgün¹, Alexander Bunck¹, Rene Botnar², Walter Heindel¹, Paulus Kirchhof¹

¹University of Münster, Münster, Germany; ²King's College, London, UK

In patients with atrial flutter, radiofrequency ablation of the isthmus between the inferior vena cava and the tricuspid valve is a common treatment procedure. In this study, we intended to investigate the feasibility to visualize ablation scars of the isthmus using MRI and to compare a standard breath-hold 2D scar imaging sequence with a high resolution free-breathing 3D scar sequence. 49 MR exams (28 before, 21 after RF ablation) were included. Sensitivity/specificity for the detection of ablation scars were 95%/79% (3D), 67%/89% (2D). We demonstrate that RF ablation scar can be visualized non-invasively with the use of T1w MRI. Visualization of scars of the isthmus in patients with atrial flutter may confirm procedural success of RF ablation and may correlate with clinical outcomes.