High-Resolution Cardiac MRI for Identification of Coronary Microvascular Dysfunction

This prospective study assessed the ability of high-resolution cardiac MRI (CMR) to detect coronary microvascular dysfunction (CMD) in 75 patients with angina and nonobstructive coronary artery disease (NOCAD), using invasive coronary physiology testing as the reference standard.

Quantitative CMR perfusion analysis — specifically the myocardial perfusion reserve (MPR) and endocardial MPR (MPRENDO) — achieved high diagnostic accuracy for CMD, with AUC values of 0.88 and 0.90 respectively. Visual assessment alone, without quantification, was significantly less accurate. The results suggest that CMR-based quantitative perfusion imaging, when quantified rather than visually interpreted, provides a noninvasive method for diagnosing CMD with clinically acceptable accuracy.

CMD — reduced perfusion due to abnormalities in the small coronary vessels rather than epicardial stenosis — is a significant and underdiagnosed cause of angina, particularly in women. Traditional nuclear stress testing often misses CMD because it evaluates relative rather than absolute perfusion. CMR with quantitative perfusion analysis fills this gap, enabling diagnosis without invasive testing in appropriate patients.

The study size is modest, and the reference standard (invasive coronary physiology) carries its own technical variability. Independent validation in larger cohorts and different laboratory settings is needed before routine clinical deployment.

We rate the evidence moderate. A well-designed prospective study establishing quantitative CMR as an accurate noninvasive diagnostic tool for CMD — clinically significant for a condition that is currently underdiagnosed and undertreated.