Simultaneous cerebral mri and mr-angiographic study of carotid arteries as screening technique for high-risk carotid atherosclerosis

Aim: The aim of the study was (1) to develop efficacious and minimally time-consuming protocol for extensive MRI and MR-angiographic examinations of carotid arteries in order to detect and quantify severity of atherosclerotic stenosis in the carotid arteries and (2) to evaluate the efficiency of this protocol in routine studies of the head in ambulatory patients aged over 45 years with clinical signs of extensive atherosclerosis. The results of MR-tomographic and MR-angiographic examinations were studied in 147 patients referred to the MRI Laboratory. Initially the protocol of MR-tomographic and MR-angiographic studies included MR-angiography of the carotid and cerebral blood vessels with an acquisition of time-of flight MR-angiograms and detailed visualization of the region of common (CCA) and internal carotid artery (ICA) stenosis, as follows: slice thickness of 1 mm, matrix of 256 х 256, voxel size of 0.2 х 0.2 х 1 mm, TR=6 ms, and TE=32 ms. Thereafter the MR-angiograms of the brain were immediately reconstructed, with on-line evaluation of the presence and severity of ICA stenosis. After that, axial sections of the brain were acquired simultaneously with axial slices of the bifurcations of carotid arteries, in T2-weighted spin-echo regime (TE=100-110 ms, TR=4000-7000 ms) and Т1-weighted spin echo regime (TE=15 ms, TR=400-600 ms), with and without fat suppression. For certain acquisition of MRI slices covering the region of CCA bifurcation, centering them at the level of the intervertebral disc С3-4 was usually enough. The study demonstrated that simultaneous acquisition of MR-angiography of the carotid arteries with MR-tomographic study of the vascular wall may be the effective method to detect intraplaque hemorrhage in the presence of carotid artery stenosis. These intraplaque haemorrhages are suggested as indication to carotid endarterectomy with autovenous plasty and for the elimination of the risk of cerebral stroke.