A Practical Approach for Quantification of Stress/Rest Myocardial Blood Volume Reserve Using Free-breathing Ferumoxytol-enhanced MRI at 0.55T

Motivation: Rest to stress myocardial blood volume reserve (MBVR) is an important physiological biomarker to detect ischemia but using T1 reactivity as its surrogate has limitations (such as dose dependence) for ferumoxytol-enhanced cardiac MRI. Goal(s): We propose a practical approach to estimate MBVR as a dose-independent biomarker. Approach: We perform beat-to-beat T1 mapping during ferumoxytol infusion to estimate extravascular T1 at blood/myocardium equilibrium, and correct the conventional T1 reactivity for it to estimate MBVR. Results: Proposed approach provided MBVR estimates consistent with the literature. MBVR, as a physiological biomarker unlike T1 reactivity, was more accurate in detecting ischemic territories than T1 reactivity. Impact: Proposed approach to estimate myocardial blood volume reserve appends a minor modification to conventional ferumoxytol-enhanced T1 reactivity protocol, and enables estimation of a dose-independent physiological biomarker to detect ischemia. This helps standardizing normal and abnormal values in clinical scenarios.