Abstract 21: Hypo-intensity of MRI Vessel Wall Imaging Indicates Advanced Intracranial Atherosclerosis With Lipid Core

Objective: Although Magnetic Resonance Imaging (MRI) vessel wall imaging could visualize the pathology of intracranial arterial disease, signal changes are poorly interpreted due to lacking of cerebral artery specimens. Based on a MRI-histology comparison study on a series of post-mortem cerebral arteries, we aimed to examine the occurrence of hyper-, iso- and hypo-intensity on T1-weighted fat-suppressed images of MCA plaques, which might be suggestive of different plaque components. Methods: Fifty-eight pairs of MCAs were imaged at 1.5T MRI with T1-weighted Table 1: The distribution of different atherosclerotic phenotypes among MCA plaques with iso-, hyper- and hypo-intensity on T1-weighted fat-suppressed images fat-suppressed- and T2-weighted sequence. MRI was performed in the postmortem brains to scan the cross-sections of MCAs with barium expanding the artery lumen. The MCAs were then removed for histopathologic processing and atherosclerotic plaque classification, which was used as a reference standard to interpret the signal changes on MRI pictures. Results: A total of 76 MRI vessel wall images were adequate for signal changes interpretation. On T1-weighted fat-suppressed images of MCA plaques, hyper-intensity was revealed on 34 vessels (44.7%), iso-intensity on 24 vessels (31.6%) and hypo-intensity was revealed on 18 samples (23.7%). There was a trend that iso-intensity indicated lower grade atherosclerosis and hypo-intensity represented advanced atherosclerosis, while hyper-intensity was suggestive of median grade atherosclerotic plaques. Further analysis demonstrated that nearly all hypo-intensity was found to be histology-verified advanced atherosclerosis with lipid core formation. Interpretation: Signals of hypo-intensity on T1-weighted fat-suppressed images of MCA plaques may be useful in stratification of stroke patients with intracranial atherosclerosis.