Hyperintense plaque identified by magnetic resonance imaging relates to intracoronary thrombus as detected by optical coherence tomography in patients with angina pectoris

Abstract

Aims: Many investigators have speculated that hyperintense plaques (HIPs) of the carotid artery on non-contrast T1-weighted imaging (T1WI) in magnetic resonance indicate the presence of mural or intraplaque haemorrhage containing methemoglobin. Coronary plaque imaging with T1WI is challenging, and the clinical significance of coronary HIP on T1WI remains unknown. The aim of this study was to compare HIPs on T1WI with coronary plaque morphology assessed by optical coherence tomography (OCT), which allows us to identify not only plaque rupture, but also fibrous cap thickness and intracoronary thrombus in vivo, in patients with angina pectoris.

Methods and results: Twenty-six lesions from 26 patients with either stable or unstable angina pectoris were examined in this study. All patients underwent T1WI within 24 h before the day on which invasive coronary angiography was performed, and pre-interventional OCT was performed on a native atherosclerotic lesion, considered to be the culprit lesion. Of the 26 lesions studied, 16 (62%) were HIPs and 10 (38%) were non-HIPs. The signal intensity of the coronary plaque to cardiac muscle ratio in HIPs was significantly higher than that in non-HIPs. There were no significant differences in the frequency of lipid-rich plaque, thin-cap fibroatheroma, plaque rupture, and calcification between HIPs and non-HIPs. In contrast, the frequency of thrombus was significantly higher in HIPs than in non-HIPs (P = 0.004).

Conclusion: This study shows that the HIPs on T1WI in angina patients relate to the presence of intracoronary thrombus as detected by OCT imaging.

Figure 1

A representative case of HIP lesion on T1WI compared with plaque morphology on OCT. (A) Whole-heart coronary MR angiography shows severe coronary stenosis (indicated by arrow) in the proximal left anterior descending coronary artery (LAD). (B and C) Coronary T1WI CMR images (B: horizontal, C: sagittal). The area corresponding to the stenotic lesion shows hyperintensity (indicated by arrow). (D) CAG shows severe coronary stenosis (indicated by arrow) in the proximal LAD. (E and F) Images (E) and (F) show intracoronary thrombus (indicated by arrowhead) that was detected by OCT in the proximal (E) and mid (F) sites of the culprit lesion.

Figure 2

A case of both HIP and non-HIP lesions in a single patient. (A and H) Whole-heart coronary MR angiographic images show severe coronary stenoses (indicated by arrow) in the proximal LAD (A), and mid right coronary artery (RCA) (H). (B, C, I) Coronary T1WI CMR images. The area corresponding to the LAD lesion shows hyperintensity [indicated by arrow in B (horizontal) and C (coronal), and the other area corresponding to the RCA lesion shows non-hyperintensity (indicated by arrow in I)]. (D and J) CAG showing severe coronary stenoses (indicated by arrow) in the proximal LAD (D) and, the mid and distal RCA (J). (E–G) Images (E) to (G) show the OCT images in the LAD lesion. Thin-cap fibroatheroma (E), plaque rupture (F), and intracoronary thrombus (G) (indicated by arrowhead) were observed in the corresponding lesion with HIP. Images (K) (mid RCA) and (L) (distal RCA) show the OCT images in the RCA lesions. Thrombus was not found in the corresponding lesions with non-HIP.