Myocardial Perfusion: Experimental Models & Human Studies
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Tuesday May 10th
Room 513A-D  10:30 - 12:30 Moderators: Rohan Dharmakumar and Michael Jerosch-Herold

10:30 214.   Adenosine-Induced Stress Myocardial Perfusion MRI Using SW-CG-HYPR with Whole Left Ventricular Coverage: Comparison of Results with X-Ray Angiography in Patients with Suspected Coronary Artery Disease  
Heng Ma1, Lan Ge2, Jing An3, David Chen2, Lixin Jin4, Xiaoming Bi5, Renate Jerecic4, Kuncheng Li1, and Debiao Li2,6
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.

10:42 215.   Cardiac ASL: optimisation and validation in the mouse heart 
Adrienne E Campbell1,2, Anthony N Price3, Jack A Wells1, Roger J Ordidge2, and Mark F Lythgoe1
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.

10:54 216.   Quantitative MRI of the Myocardial Microcirculation in Mice using FAIR Look-Locker Arterial Spin Labeling and a Gamma-variate Model of Blood Transit Time Distribution 
Frederick H Epstein1,2, Nivedita K Naresh2, Patrick F Antkowiak2, Moriel H Vandsburger2, and Xiao Chen2
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.

11:06 217.   Detecting Myocardial Ischemia at Rest with Cardiac Phase-Resolved BOLD MRI: Early Findings 
Sotirios Athanasios Tsaftaris1,2, Veronica Rundell2, Xiangzhi Zhou2, Ying Liu2, Richard Tang2, Debiao Li2, and Rohan Dharmakumar2
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.

11:18 218.   Methods for Quantification of Absolute Myocardial Oxygen Consumption with 17O-CMR 
David Muccigrosso1, Xiang He2, Dana Abendschein1, Adil Bashir1, Pradeep Gupte3, Wei Chen4, Robert J. Gropler1, and Jie Zheng1
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.

11:30 219.   Rapid CINE Myocardial T2* Mapping at 7T 
Fabian Hezel1, Peter Kellman2, Christof Thalhammer1, Wolfgang Renz3, and Thoralf Niendorf4,5
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.

11:42 220.   Pyruvate is Superior to Glucose in Supporting Metabolism of Machine Perfused Donor Hearts for Transplantation 
Michael Cobert1, Matthias Peltz1, Matthew Merritt2, LaShondra West1, and Michael E Jessen1
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.

11:54 221.   Myocardial ASL perfusion reserve test detects angiographic CAD in initial cohort of 29 patients 
Zungho Zun1, Terrence Jao1, Padmini Varadarajan2, Ramdas G Pai2, Eric C Wong3, and Krishna S Nayak1
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.

12:06 222.   Self-gated Cardiac Perfusion MRI 
Edward DiBella1, Ganesh Adluru2, Liyong Chen3, and Chris McGann4
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.

12:18 223.   Endothelial Progenitor Cells Mediated Improvements in Post-Infarct Left Ventricular Myocardial Blood Flow Estimated by Spin Labeling CMR 
Hua-Lei Zhang1,2, Hui Qiao1, Rachel S Frank1, Stephanie Eucker2, Bin Huang1, William M Armstead3, Victor A. Ferrari4, Jonathan A. Esptein4, and Rong Zhou1
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.