Vessel wall analysis of intracranial major artery stenosis using 3T MRI

Abstract

It has been even difficult to delineate a local atherosclerotic focus in cerebral artery stenosis, because of its smallness of relevant arteries and thinness of that vessel wall. Recently 3T MRI has shown up, which has a superior S/N ratio and a frequency resolution, enabling main cerebral arteries to be more clearly delineated. Thus, we have tried to visualize the arterial wall and the atherosclerotic local lesion with use of a brand-new sequence of 3T MRI. Twelve cases suspected to have a stenosis of unilateral middle cerebral artery (MCA) on TOF-MR angiography (MRA) were collected as a stenosis group. For the vessel wall analysis, all cases underwent a new sequence of T1-CUBE using 3T MRI (SIGNA HDxt: GE healthcare), and images were reformatted to observe both short and long axis directions of bilateral M1 portion of MCA, on which the maximal wall thickness on a short axis following after the observation on a long axis in each case was measured. And 10 cases without cerebral artery stenosis were recruited as a normal group for control. Besides, in the stenosis group the comparison between stenosis ratio on MRA and mean wall thickness was also performed. The arterial wall was apparently delineated as high signal intensity on the image obtained with T1-CUBE sequence. In a stenosis group, mean thickness of the arterial wall in a healthy side was 1.19 ± 0.08 mm, whereas that in a lesion side was 1.57 ± 0.27 mm, where a significant difference was seen between both sides (p<0.05). Meanwhile, the mean arterial wall thickness in a normal group was 0.85 ± 0.23 mm, which was significantly smaller than that in both healthy and lesion side of a stenosis group (p<0.05, p<0.001, respectively). Moreover, there was significant correlation between stenosis ratio and mean wall thickness in stenosis group (R=0.69, p=0.019). Given our results the arterial wall in cases with a stenosis of intracranial main artery should have an atherosclerotic change, which was shown in T1-CUBE image as a high signal lumen, like carotid artery stenosis. Accordingly, for the next step, it would be crucial to evaluate contents of the atherosclerotic plaque in that stenotic lesion.