Advantage in Bright-blood and Black-blood Magnetic Resonance Imaging with High-resolution for Analysis of Carotid Atherosclerotic Plaques

Background： About 50% of the cerebral ischemia events are induced by intracranial and extracranial atheroscterosis. This study aimed to evaluate the feasibility and accuracy for displaying atherosclerotic plaques in carotid arteries and analyzing their ingredients by using high-resolution new magnetic resonance imaging （MRI） techniques. Methods： Totally, 49 patients suspected ofextracranial carotid artery stenosis were subjected to cranial MRI scan and magnetic resonance angiography （MRA） examination on carotid arteries, and high-resolution bright-blood and black-blood MRI analysis was carried out within 1 week. Digital subtraction angiography （DSA） examination was carried out for 16 patients within I month. Results： Totally, 103 plaques were detected in the 49 patients, which were characterized by localized or diffusive thickening of the vessel wall, with the intrusion of crescent-shaped abnormal signal into lumens. Fibrous cap was displayed as isointensity in T I -weighted image （T I WI） and hyperintensities in proton density weighted image （PDWI） and T2-weighted image （T2WI）, lipid core was displayed as isointensity or slight hyperintensities in T1WI, isointensity, hyperintensities or hypointensity in PDWI, and hypointensity in T2WI. Calcification in plaques was detected in 11 patients. Eight patients were detected with irregular plaque surface or ulcerative plaques, which were characterized by irregular intravascular space surface in the black-blood sequences, black hypointensity band was not detected in three-dimensional time-of-flight, or the hypointensity band was not continuous, and intrusion of hyperintensities into plaques can be detected. Bright-blood and black-blood techniques were highly correlated with the diagnosis of contrast-enhanced MRA in angiostenosis degree, Rs 0.97, P 〈 0.001. In comparison to DSA, the sensitivity, specificity, and accuracy of MRI diagnosis of stenosis for ≥50% were 88.9%. 100%, and 97.9%, respectively. Conclusions： High-resolution bright-blood and black-blood sequential MRI analysis can accurately analyze ingredients in atherosclerotic plaques, Determined by DSA, MRI diagnosis of stenosis can correctly evaluate the serious degree of arteriostenosis.

Quantitative comparisons between relaxation enhanced compressed sensing 3D MERGE and conventional 3D MERGE for vessel wall imaging in equal scan time: preliminary studies

In this study, we quantitatively compared relaxation enhanced compressed sensing(RECS-3D MERGE) with conventional 3D MERGE techniques on blood suppression efficiency, wall-lumen contrast and plaque burden measurement for carotid atherosclerotic imaging in equal scan time. Twelve patients were recruited in the study. RECS-3D MERGE and conventional 3D MERGE were implemented. 2D DIR-FSE was carried out as a reference standard. The lumen signal-to-tissue ratio(STR) was used as the quantitative measure of blood suppression efficiency. The contrast-to-tissue ratio(CTR) was used as the quantitative measure of wall-lumen contrast. Vessel lumen area(LA) and wall area(WA) were measured for morphological comparisons. The lumen STR of RECS-3D MERGE was significantly lower than that of 3D MERGE while the wall-lumen CTR of RECS-3D MERGE was significantly higher. There were no significant differences in plaque burden measurements between RECS-3D MERGE and 2D DIR-FSE. For comparison between conventional 3D MERGE and 2D DIR-FSE, there were no significant differences in LA measurement. However, the WA of 3D MERGE was significantly larger. The RECS-3D MERGE sequence achieved more sufficient blood suppression and higher image contrast without prolonging the scan time. These improvements lead to more accurate morphological measurements of carotid atherosclerotic imaging.