Heng Ma¹, Lan Ge², Jing An³, David Chen², Lixin Jin⁴, Xiaoming Bi⁵, Renate Jerecic⁴, Kuncheng Li¹, and Debiao Li^2,6
1Xuanwu Hospital, Capital Medical University, Beijing, Beijing, China, People's Republic of, ²Northwestern University, ³Siemens Healthcare, MR Collaboration NE Asia, Siemens Mindit Magnetic Resonance, ⁴Siemens Healthcare, MR Collaboration NE Asia, Siemens Limited China, ⁵Siemens Healthcare, Cardiovascular MR R&D, USA, ⁶Cedars-Sinai Medical Center and UCLA

Myocardial perfusion MRI with SW-CG-HYPR allows increased spatial coverage (whole left ventricular coverage), resolution, signal-to-noise ratio and reduced motion artifacts. The accuracy of this technique for detecting CAD has not been determined in a large number of patients. In this work, we have prospectively examined the diagnostic value of adenosine-induced stress myocardial perfusion MRI using SW-CG-HYPR in 50 patients with suspected CAD. Using the SW-CG-HYPR method, perfusion MRI was able to cover the whole left ventricle with an accuracy of 90% and 93% based on per-patient and per-vessel analyses, respectively, using X-ray coronary angiography as a reference standard.

Adrienne E Campbell^1,2, Anthony N Price³, Jack A Wells¹, Roger J Ordidge², and Mark F Lythgoe^1
1Centre for Advanced Biomedical Imaging, Division of Medicine and Institute of Child Health, University College London, London, United Kingdom, ²Department of Medical Physics and Bioengineering, University College London, London, United Kingdom, ³Robert Steiner MRI Unit, Imaging Science Department, Hammersmith Hostpital, Imperial College London, London, United Kingdom

A time-efficient arterial spin labelling sequence was implemented to measure perfusion in the mouse heart. Data acquisition was improved using a data logger for additional cardiac gating and the generation of objective criteria for rejection of respiration corrupted images. A validation study was performed on 8 CD-1s to analyse the sources of variability in this technique, and to quantify the repeatability of this technique for group comparisons and for longitudinal studies. It was found that between animal variations were larger than technique variations and that achievable changes in perfusion were required for observation of group differences, beyond technique error.

Frederick H Epstein^1,2, Nivedita K Naresh², Patrick F Antkowiak², Moriel H Vandsburger², and Xiao Chen^2
1Radiology, University of Virginia, Charlottesville, Virginia, United States, ²Biomedical Engineering, University of Virginia, Charlottesville, Virginia, United States

Experimental therapies for ischemic heart disease are widely investigated in mouse and rat models. For these investigations, a multi-parametric assessment of the microcirculation would be highly valuable. We developed a kinetic analysis for arterial spin labeling (ASL) based on a gamma-variate blood transit model that enables the estimation of myocardial blood flow (MBF), myocardial blood volume (MBV), and mean transit time (MTT). An initial experimental evaluation of this method was performed in mice. Kinetic ASL with a gamma-variate-based model of the blood transit time distribution shows promise for quantifying multiple parameters of the microcirculation in the mouse heart.

Sotirios Athanasios Tsaftaris^1,2, Veronica Rundell², Xiangzhi Zhou², Ying Liu², Richard Tang², Debiao Li², and Rohan Dharmakumar^2
1Electrical Engineering and Computer Science, Northwestern University, Evanston, IL, United States, ²Radiology, Northwestern University, Chicago, IL, United States

Vasodilatory stress has been used to probe myocardial oxygenation changes due to coronary artery stenosis on the basis of BOLD MRI. However, since vasodilation is typically achieved with provocative stress, approaches that can identify the presence of stenosis on the basis of microvascular alterations at rest are highly desirable. In this work, using controlled animals studies and theoretical simulations we demonstrate that cardiac phase-resolved BOLD MRI may be used to identify ischemic territories at rest.

David Muccigrosso¹, Xiang He², Dana Abendschein¹, Adil Bashir¹, Pradeep Gupte³, Wei Chen⁴, Robert J. Gropler¹, and Jie Zheng^1
1Washington University School of Medicine, St. Louis, MO, United States, ²University of Pittsburg, ³Rockland Technimed, Ltd., ⁴University of Minnesota

A cardiac MR acquisition method and comprehensive model were developed to quantify regional absolute myocardial oxygen consumption using ¹⁷O-labeled perfluorocarbon compounds. Experiments were performed in normal and stenotic dogs to evaluate these methods. The calculated oxygen consumption rates agreed well with results in the literature. Mismatched areas between myocardial blood flow and oxygen deficit were observed in severely ischemic regions.

Fabian Hezel¹, Peter Kellman², Christof Thalhammer¹, Wolfgang Renz³, and Thoralf Niendorf^4,5
1Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine, Berlin, Germany, ²Laboratory of Cardiac Energetics, National Institutes of Health/NHLBI, Bethesda, MD, United States, ³Siemens Medical Systems, Erlangen, Germany, ⁴Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine, Berlin, Berlin, Germany, ⁵Experimental and Clinical Research Center (ECRC), Charité Campus Buch, Humboldt-University, Berlin, Germany

Rapid CINE T2* Mapping of the heart has been demonstrated at 7T using a multi-echo gradient echo technique. Macroscopic B0 inhomogeneities have been reduced by high in-plane spatial resolution and volume selective shimming. Myocardial T2* was found to vary over myocardium and over the cardiac cycle.

Michael Cobert¹, Matthias Peltz¹, Matthew Merritt², LaShondra West¹, and Michael E Jessen^1
1Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States, ²Advanced Imaging Research Center, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States

Machine perfusion preservation appears to be a useful strategy for donor heart preservation prior to transplantation. An exogenous substrate in the preservation solution may limit depletion of endogenous energy stores and further improve donor heart preservation. We compared carbon-13 labeled glucose and pyruvate as metabolic substrates for the stored heart using 1H and 13C magnetic resonance spectroscopy. We demonstrated that pyruvate, even at low concentrations, is effective in supporting the metabolic demands of the cold perfused heart. These findings may have important implications for increasing the cardiac donor pool and improving results of heart transplantation.

Zungho Zun¹, Terrence Jao¹, Padmini Varadarajan², Ramdas G Pai², Eric C Wong³, and Krishna S Nayak^1
1Department of Electrical Engineering, University of Southern California, Los Angeles, CA, United States, ²Division of Cardiology, Loma Linda University Medical Center, Loma Linda, CA, United States, ³Departments of Radiology and Psychiatry, University of California, San Diego, La Jolla, CA, United States

Rest-stress myocardial arterial spin labeled (ASL) MRI was performed in twenty-nine patients with suspected coronary artery disease (CAD). Perfusion reserve was estimated in six myocardial segments of a single mid short-axis slice, and compared with X-ray angiography. Receiver operating characteristic (ROC) curves were analyzed for (i) detection of patients with angiographic CAD and (ii) detection of the most ischemic segments. The area under ROC curves were (i) 0.88 and (ii) 0.71.

Edward DiBella¹, Ganesh Adluru², Liyong Chen³, and Chris McGann^4
1University of Utah, Salt Lake City, Utah, United States, ²Radiology, University of Utah, ³Bioengineering, University of Utah, ⁴Cardiology, University of Utah

Good ECG-gating is essential to obtaining the same cardiac phase of each slice to maximize the value of dynamic contrast enhanced cardiac perfusion scans. However, ECG-gating is often poor, and can be more problematic at higher field strength scanners and in obese patients. As well, patients with arrhythmias can be problematic for acquiring high quality images due to the R-R interval variations. Here we propose an ungated perfusion acquisition that runs constantly without any gating signals. The images are acquired so rapidly that it is possible to sort the resulting dataset and create effectively self-gated perfusion images.

Hua-Lei Zhang^1,2, Hui Qiao¹, Rachel S Frank¹, Stephanie Eucker², Bin Huang¹, William M Armstead³, Victor A. Ferrari⁴, Jonathan A. Esptein⁴, and Rong Zhou^1
1Laboratories of Molecular Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States, ²Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States, ³Department of Anesthesia, University of Pennsylvania, Philadelphia, PA, United States, ⁴Department of Medicine (Division of Cardiovascular Medicine), University of Pennsylvania, Philadelphia, PA, United States

Spin Labeling-CMR allowed high resolution mapping of myocardial blood flow (perfusion) in small animals which have rapid heart rates (400-600 bpm). The absolute perfusion values by Spin Labeling-CMR were in excellent agreement with those obtained by standard but invasive fluorescent microsphere method. This noninvasive method enabled serial monitoring of myocardial perfusion improvement in response to stem cell engraftment. Such capability is crucial in the development of cell therapy for myocardial infarction.