Electronic Posters: Cardiovascular

Tuesday 13:30-15:30 Computer 35

13:30 3668. Prospective Respiratory Navigator Gated RF Excitation in Whole-Heart Coronary MRA at 3T

Jing Yu^1,2, Michael Schär, ²³, Harsh Agarwal, ^2,4, Matthias Stuber<sup>2,5

1</sup>Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States; ²Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, United States; ³Philips Healthcare, Cleveland, OH, United States; ⁴Department of Electrical and Computer Engineering, John Hopkins University, Baltimore, MD, United States; ⁵Department of Radiology, University Hospital Center and University of Lausanne (CHUV), Lausanne, VD, Switzerland

One of the challenges in coronary MRA is insufficient SNR. To improve the blood-pool SNR in prospective respiratory navigator gated whole-heart coronary MRA, radiofrequency excitations of the gradient echo readout train are suspended in real-time, when the respiratory position is outside the predefined gating window. Phase encoding is adapted to deposit the increased signal in central k-space and to minimize signal variation of adjacent k-space profiles. Consistent with the numerical simulation, in vivo experiments demonstrated 35% improvement in blood-pool SNR, without compromising scan time or spatial resolution. The SNR advantage affords great potential towards better depiction of the coronary arteries.

14:00 3669. Coronary Sinus Flow Quantification at 3T and Cold Pressor Test for Non Invasive Evaluation of Coronary Endothelial Function

Pierre-Julien Moro^1,2, Alexis Jacquier¹, Frank Kober¹, Jean-Louis Bonnet², Patrick Cozzone¹, Monique Bernard<sup>3

1</sup>Centre de Résonance Magnétique Biologique et Médicale, CNRS UMR 6612, Université de la Méditerranée, Faculté de Médecine, Marseille, France; ²Cardiology, CHU Timone, Marseille, France; ³Centre de Résonance Magnétique Biologique et Médicale, CNRS UMR 6612, Université de la Méditerranée , Faculté de Médecine, Marseille, France

The purpose of this study was to assess a non invasive measure of coronary endothelial function. Coronary sinus flow was measured in 14 volunteers at rest and during cold pressor test (CPT) using non breath-hold velocity encoded phase contrast cine MRI. Myocardial blood flow (MBF) significantly increased by 55 ± 38 % during CPT compared to the rest examination (p<0.0001); coronary blood flow was 0.66 ± 0.22 ml/min/g at baseline and 1.03 ± 0.41 ml/min/g after CPT. This non invasive measure may help to detect changes in endothelial function which occur early in a variety of cardiovascular diseases.

14:30 3670. Prospective Projection-Based Respiratory Whole-Heart Coronary MRI with Patient-Specific Tracking Factor

Mehdi Hedjazi Moghari¹, Peng Hu¹, Christian Stoeck², Jouke Smink³, Dana C. Peters¹, Beth Goddu¹, Lois Goepfert¹, Warren J. Manning¹, Reza Nezafat<sup>1

1</sup>Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States; ²University and ETH, Biomedical Engineering, Zurich, Switzerland; ³Philips-Healthcare, Best, Netherland

The impact of correct subject-dependent slice tracking factor in whole-heart coronary imaging is studied in this paper. In preparation phase, two projection-based respiratory navigators are positioned at the diaphragm edge and center of heart to calculate the slice tracking factor. The projection-based navigator at the diaphragm with the estimated scale factor is employed for the whole-heart coronary image reconstruction. The constructed images outperform the ones acquired with the pencil beam navigator with the constant scale factor 0.6.

15:00 3671. Feasibility Study of Motion Pre-Analysis Method for Whole-Heart Magnetic Resonance Coronary Angiography (Wh Mrca) at Different Breathing Levels

Shigehide Kuhara¹, Tomohisa Okada², Ayako Ninomiya¹, Toshikazu Kamae², Shotaro Kanao², Tetsuo Sato³, Kotaro Minato³, Kaori Togashi<sup>2

1</sup>MRI Systems Division, Toshiba Medical Systems, Otawara-Shi, Tochigi, Japan; ²Department of Diagnostic Radiology, Kyoto University Hospital, Kyoto, Japan; ³Nara Institute of Science and Technology, Nara, Japan

We have developed the Motion Pre-Analysis Method to determine the appropriate RMC coefficient before WH MRCA (Whole Heart Magnetic Resonance Coronary Angiography) examinations and investigated coefficients between motions of the diaphragm and the heart at different breathing levels by using an inflatable blood pressure cuff placed under an abdominal band. The results of this study suggest that the RMC coefficient may change for each person and abdominal pressures applied. The image quality was slightly improved by using the pre-analyzed RMC coefficient. It is therefore expected that this Motion Pre-Analysis Method would improve visualization of WH MRCA examinations.