Advances in stress cardiac MRI and computed tomography

Abstract

Stress cardiac MRI and stress computed tomography (CT) perfusion are relatively new, noninvasive cardiovascular stress-testing modalities. Both of these tests have undergone rapid technical improvements. Data from randomized controlled trials in stress cardiac MRI are becoming gradually incorporated into cardiovascular clinical practice, not only to assess physiological significance of coronary artery disease, but also to provide prognostic information. As CT perfusion protocols become more uniform with adequate handling of artifacts and decreasing radiation exposure with combined CT coronary angiography/CT perfusion imaging, it has the potential to become a comprehensive diagnostic test.

Figure 1. Qualitative interpretation of cardiac magnetic resonance perfusion imaging

(A) Top row shows adenosine stress images, while the (B) 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, inferolateral, inferior and inferoseptal wall, extending from the basal to the apical slice. Adapted with permission from [22].

Figure 2. Comparison of stress cardiac magnetic resonance perfusion analysis with 1.5 versus 3 T scanners, with invasive coronary angiogram as gold standard

(A) Threshold of ≥50% stenosis. (B) Threshold of ≥70% stenosis. LGE: Late gadolinium enhancement. Adapted with permission from [16].

Figure 3. Relationship between 3D whole-heart stress cardiac magnetic resonance with fractional flow reserve

Dotted line represents mean fractional flow reserve: 0.82 (normal CMR) versus 0.61 (abnormal CMR). CMR: Cardiac MRI. Adapted with permission from [17].

Figure 4. Quantitative perfusion analysis on stress cardiac magnetic resonance

(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 coronary artery disease. 1V: Single vessel; 3V: Three vessel; CAD: Coronary artery disease; LV: Left ventricle. Adapted with permission from [22].

Figure 5. Comparison of automatically generated contrast enhancement curves with manual tracing

Stress-induced perfusion abnormality is noted in the inferior and lateral walls. Manual tracing resulted in virtually identical curves both (A) at rest (top row) and (B) stress (bottom row). Adapted with permission from [25].

Figure 6. Dynamic computed tomography perfusion in a patient with a history of coronary artery bypass graft

(A) Nearly transmural perfusion defect in the inferior wall. (B) Time attenuation curves demonstrate attenuation in the inferior walls to be lower compared with other segments. Adapted with permission from [70].

Figure 7. Comparison of cardiovascular computed tomography angiography/computed tomography perfusion with conventional coronary angiography/fractional flow reserve as gold standard (n per vessel)

CCA: Conventional coronary angiography; CCTA: Cardiovascular computed tomography angiography; CTP: Computed tomography perfusion; FFR: Fractional flow reserve. Adapted with permission from [45].