Cardiac MRI assessment of myocardial perfusion

Abstract

Coronary artery disease is the most common cause of mortality and morbidity around the globe. Assessment of myocardial perfusion to diagnose ischemia is commonly performed in symptomatic patients prior to referral for cardiac catheterization. Among other noninvasive imaging modalities, cardiac MRI (CMR) is emerging as a highly sensitive and specific test for myocardial ischemia and infarction. Resting perfusion on CMR is used to evaluate for microvascular obstruction, which is shown to predict adverse left ventricular remodeling and cardiac events after acute myocardial infarction. This article summarizes the current understanding of CMR perfusion.

Keywords: 3D perfusion; cardiac MRI; fractional flow reserve; microvascular obstruction; myocardial perfusion; quantitative perfusion; rest; stress.

Figure 1. Vasodilator stress cardiac MRI protocol at our center

IV: Intravenous; LGE: Late gadolinium enhancement; SSFP: Steady state free precession.

Figure 2. Qualitative interpretation of cardiac MRI perfusion imaging.

Top row shows adenosine stress images, while the bottom row shows rest images. Left column: basal left ventricle; middle column: mid left ventricle; right column: apical left ventricle. The white arrows point to a large perfusion defect in the anterolateral, infero-lateral, inferior and infero-septal wall, extending from the basal to the apical slice. Adapted with permission from [6].

Figure 3. Typical pattern of microvascular obstruction in a patient with ST-elevation myocardial infarction due to an occluded left anterior descending artery, treated with primary percutanous coronary intervention

(A) Demonstrates first pass perfusion images with hypoperfusion of the anteroseptum, especially at day 2 and week 1 postmyocardial infarction. (B) Demonstrates late gadolinium-enhanced images with the dark signal at the subendocardium at each time point representing regions of microvascular obstruction. LV: Left ventricle; RV: Right ventricle. Adapted with permission from [9].

Figure 4. Quantitative perfusion analysis on stress cardiac MRI. (A)

Relationship between perfusion reserve and percentage stenosis on cardiac catheterization. (B) Comparison of qualitative perfusion analysis with perfusion reserve to assess degree of ischemia in single and multivessel CAD. CAD: Coronary artery disease; LV: Left ventricle. Adapted with permission from [6].