BOLD-MRI in ten patients with coronary artery disease: evidence for imaging of capillary recruitment in myocardium supplied by the stenotic artery

摘要

Changes of myocardial oxygenation can be studied by measurements of the apparent transverse relaxation time T_2~*, which is correlated with the oxygenation state of hemoglobin. In this study, ten patients with coronary artery disease (CAD) underwent blood oxygenation level dependent (BOLD) T_2~* measurements using a segmented gradient echo pulse sequence with ten echoes. T_2~* measurements were performed in a single short-axis slice of the heart at rest and under pharmacological stress with dipyridamole (DIP), which increases myocardial blood flow. For comparison, all patients underwent X-ray angiography and stress-echocardiography within 4 days after the MR exam. In one patient, MR examination was repeated 10 weeks after percutaneous transluminal coronary angioplasty (PTA). In the differential T_2~* maps, expected ischemic areas of myocardium were identified in six patients. In these regions, T_2~* values (30 +- 8 ms) were significantly reduced when compared to the remaining myocardium (48 +- 9 ms, P < 0.01). In four patients, the myocardial region of interest could not be assessed owing to severe susceptibility artifacts in the ischemic region. The success of the PTA treatment could be visualized from a more homogeneous DIP induced increase in T_2~* within the ischemic myocardium (from 26 +- 1 to 29 +- 1 ms before PTA versus 26 +- 1 to 31 +- 4 ms after PTA, P<0.001).