Hsin-Jung Yang, PhD
Assistant Professor
Cedars-Sinai Medical Center
Los Angeles, California, United States
Hsin-Jung Yang, PhD
Assistant Professor
Cedars-Sinai Medical Center
Los Angeles, California, United States
Chia-Chi Yang
Research Associate
Cedars-Sinai Medical Center, United States
Anthony G. Christodoulou, PhD
Assistant Professor
Cedars-Sinai Medical Center
Los Angeles, California, United States
Janet Wei, MD
Assistant Professor
Cedars Sinai Medical Center
Los Angeles, California, United States
Alan C. Kwan, MD, MSc
Imaging cardiologist
Cedars-Sinai Medical Center, United States
Ghazal Youseff
Graduate student
Indiana University School of Medicine, United States
Yuheng Huang, MS
Visiting Graduate Student
Indiana University School of Medicine, Indiana, United States
.jpg "Xinheng Zhang, MSc photo")
Xinheng Zhang, MSc
Ph.D. Candidate
Indiana University School of Medicine
Indianapolis, Indiana, United States
Xingmin Guan, PhD
Postdoctoral Fellow
Indiana University School of Medicine
San Diego, California, United States
Xiaoming Bi
Director
Siemens Healthineers, California, United States
Fei Han, Ph.D.
Senior Scientist
Siemens Medical Solutions USA, Inc.
LOS ANGELES, California, United States
Yinyin Chen, MD
Attending Radiologist
Zhongshan Hospital, Fudan University and Shanghai Institute of Medical Imaging, Shanghai, China
LOS ANGELES, California, China (People's Republic)
Hui Han, PhD
Associate professor
Cedars-Sinai Medical Center
Los Angeles, California, United States
Damini Dey, PhD
doctor
Cedars-Sinai Medical Center, Los Angeles, California, USA, California, United States
Debiao Li, PhD
Professor
Cedars-Sinai Medical Center
Los Angeles, California, United States
Frank S Prato, PhD
Professor
Lawson Health Research Institute, Ontario, United States
Rohan Dharmakumar, PhD
Professor of Medicine, Radiology & Imaging Sciences, Anatomy, Cell Biology & Physiology
Krannert Cardiovascular Research Center, Indiana University School of Medicine
Indianapolis, Indiana, United States
Coronary vasodilation following the administration of a stressor is a dynamic process. The slow clearance of exogenous contrast agents limits the true assessment of time-resolved changes in blood flow and oxygenation in response to a coronary vasodilator. Blood-oxygenation-level-dependent cardiac MRI (BOLD CMR) is a non-contrast approach for probing the myocardial oxygenation balance. BOLD utilizes the intrinsic contrast from the deoxygenated hemoglobin and reflects real-time oxygenation levels in the target organs. However, conventional BOLD CMR techniques are limited by imaging speed and imaging confounders. Recently, our team has developed a confounder-corrected, highly time-resolved myocardial BOLD CMR technique. [1] Here, we investigated the capability of the time-resolved BOLD CMR approach in monitoring the dynamic vasodilation response during pharmacological stress. We validated our approach with invasive real-time optical oximetry measurements in the coronary sinus.
Methods:
A continuously acquired, free-breathing, ungated T2-BOLD sequence was developed (Fig.1A) and was studied using dogs (N=4) with institutional approval. All animals were scanned in a clinical 3T scanner. The sequence was prescribed continuously while administering a clinical pharmacological stress agent (Regadenoson). For synchronization purposes, beat-by-beat R-R interval was derived from the self-navigator signal from CMR acquisition(Fig. 1B). To validate the BOLD measurement, the coronary sinus (CS) blood oxygenation level was measured using an invasive real-time optical oximetry catheter (Edwards Lifesciences, HemoSphere). The BOLD and invasive oximetry signals were matched to the heartbeats.
Results:
Representative results from an animal are presented in Fig.2. Panel A shows the short-axis, time-resolved BOLD images. The image quality was stable throughout the pharmacological stimulation with a prominent BOLD signal increase following regadenoson injection. The BOLD response was accompanied by significant heart rate elevation. A similar trend was present in the invasive venous blood oxygenation level(SvO2%) measurements determined in the CS. Panel B shows the location of the oximetry catheter in the CS where the oximetry measurements were made during regadenoson injection. After the regadenoson injection, the CS blood oxygenation level increase to near 100% and slowly decreased after 5 minutes. The time-resolved SvO2% and BOLD response showed strong temporal alignment, demonstrating the capability of BOLD CMR in portraying the real-time noninvasive oxygenation response during pharmacological stress.
Conclusion:
We have developed an ungated beat-by-beat time-resolved BOLD CMR technique to monitor instantaneous changes in myocardial oxygenation during stress exams. The proposed approach may open opportunities to explore important insights into the vasomotor activity of coronary vessels, which is known to be impaired in numerous pathologies that affect the heart.