Improved Myocardial Perfusion Assessment using High-Performance Low-Field MRI

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PROJECT SUMMARY This project will develop and evaluate an improved tool for myocardial perfusion assessment, that will be simple, robust, and provide improved ability to resolve myocardial layers. We will achieve this by leveraging a novel high-performance low-field (HPLF) magnetic resonance imaging (MRI) platform. Rationale: Coronary artery disease (CAD) is the leading cause of death in the United States. Myocardial perfusion imaging is an essential tool in patient management, and prognostication. Myocardial first-pass perfusion (FPP) MRI is the leading non- invasive and radiation-free technique; however, it suffers from imaging artifact, limited coverage, and limited ability to resolve myocardial layers. Resolving these issues will improve our ability to detect, manage, and understand CAD. Innovation: We expect MRI FPP to greatly benefit from the HPLF MRI platform, because it promises substantially reduced artifacts, and opportunities for improved spatial coverage, spatial resolution, and temporal resolution. This project will leverage an HPLF system operating at 0.55 Tesla, to achieve improved myocardial perfusion assessments, compared to what is possible today on 1.5 Tesla and 3 Tesla systems. We will also apply novel real-time imaging techniques to avoid the need for an electrocardiogram (ECG) signal. Approach: We will develop 0.55T whole-heart MRI FPP using two contrast generation sequences in combination with stack-of-spiral (SOS) acquisition—one that uses ECG-gating and saturation recovery preparation, and one ungated approach that retrospectively identifies stable phases. The SOS sampling pattern will be optimized for CNR, boundary sharpness, and precision of myocardial perfusion measurements. Achieved spatial coverage, spatial resolution, temporal resolution, and SNR/CNR will be measured using phantoms, 10 volunteer scans, and 10 patient scans. The optimized HPLF methods will then be tested in a cohort of patients (N=20) with known non-transmural scar, and compared with standard 3T multi-slice MRI FPP, to technically validate the ability to detect non-transmural patterns of hypoperfusion, and to evaluate relative artifact levels. Broader Impact: This project will provide 0.55T MRI FPP with reduced artifact and improved spatial information, compared to what is possible at conventional MRI field strengths. In the long term, this approach could improve the diagnosis and assessment of CAD. The imaging methods developed in this project will broadly benefit cardiac and dynamic imaging on HPLF MRI platforms.