Abstract 620: Hyperintense Plaque Visualized on Noncontrast T1-Weighted Magnetic Resonance Coronary Plaque Imaging is Associated With High-Risk Coronary Plaque
Magnetic resonance (MR) imaging is well known to have the excellent soft tissue characterization and a great potential to evaluate the properties of the vessel wall and atherosclerotic plaque, although multi-slice computed tomography (MSCT) has rapidly improved regarding the diagnosis of coronary artery disease. Therefore, MR imaging has recently been identified as an effective noninvasive screening and diagnostic modality for high-risk coronary plaque, or so-called vulnerable plaque. We assessed the hypothesis that the signal hyperintense lesions visualized on noncontrast T1-weighted (T1W) MR coronary plaque imaging, which correspond to plaque lesions on MSCT, represent plaques which are prone to rupture as reported in carotid artery disease. A total of 33 patients (13 with acute coronary syndrome (ACS) including non ST elevated myocardial infarction and unstable angina, 20 with non-ACS) who were diagnosed to have coronary plaques by MSCT were enrolled. Noncontrast T1W MR coronary plaque imaging was examined before coronary intervention and the signal intensity of the plaque to muscle ratio (PMR) of all plaque was calculated. The PMR was obtained from the signal intensity at the lesions corresponding to the coronary plaques detected by MSCT and divided by that of the adjacent cardiac muscle, and the PMR>1.0 was defined as hyperintense plaque (HIP). As a result, a total of 197 plaques were detected by MSCT, and 143 were identified as HIP (73%), with a mean PMR of 1.36±0.37. In the culprit lesions, both the percentage of HIP and the mean PMR were significantly higher than in the non-culprit lesions (94% vs. 68%, p=0.008, and 1.66±0.59 vs. 1.27±0.20, p<0.001). Similar results were confirmed in both the ACS and non-ACS groups, respectively (ACS: 93% vs. 63%, p=0.0297, and 1.73±0.77 vs. 1.29±0.22, p=0.002; non-ACS: 95% vs. 71%, p=0.0235, and 1.62±0.45 vs. 1.26±0.19, p<0.001). In conclusion, the HIP with higher PMR visualized on T1W MR coronary plaque imaging was more often seen in culprit lesions in coronary artery disease. These results suggest that T1W MR imaging has great potential to noninvasively depict vulnerable coronary atherosclerotic plaques.