The Significance of Vascular MR Contrast Enhancement in Carotid Stenosis

PURPOSE: To determine the significance of vascular MR contrast enhancement in carotid stenosis. MATERIALS AND METHODS: Forty patients that had angiographically proved carotid stenosis were selected for the study. A blind interpretation of vascular enhancement on an enhanced T1 weighted image, the lesion pattern on a DWI (diffusion weighted image), a perfusion defect on a MR perfusion image, the degree of stenosis, and collateral flow on cerebral DSA (digital subtraction angiography) was made by two observers, retrospectively. DWI lesion patterns were classified as having no high signal intensity, small PAI (perforating artery infarcts), large PAI, pial infarcts, territorial infarcts, and border zone infarcts. We evaluated the statistical correlation between vascular enhancement and the degree of stenosis, collateral flow, the DWI lesion pattern and the presence of a perfusion defect, respectively. RESULTS: The degree of carotid stenosis and the frequency of vascular enhancement correlated statistically (p=0.000). The presence of retrograde collateral flow on cerebral DSA and the border zone infarcts pattern on DWI were related with the occurrence of vascular enhancement (p=0.002, p=0.004). In 23 patients that underwent a MR perfusion study, the presence of a perfusion defect was also related to the occurrence of vascular enhancement (p=0.002). CONCLUSION: Vascular MR contrast enhancement may indicate a cerebral hypoperfusion in carotid stenosis.

Results of Carotid Artery Stenting using Filter Wire in 24 Consecutive Symptomatic Patients with Severe Stenosis

PURPOSE: The aims of this study were to analyze the results of carotid artery stenting using distal protection with FilterWire, and evaluate the effectiveness of FilterWire for distal embolic protection. MATERIALS AND METHODS: Between June and December in 2004, elective carotid artery stenting using FilterWire was attempted in 25 lesions of 24 consecutive patients. All patients were symptomatic, with recurrent transient ischemic attacks (TIA) or a stroke. The cerebral ischemic lesions of embolic origin were evaluated before and after the procedure using magnetic resonance imaging, including diffusion-weighted images. Both pre- and post-procedural 99mcTc-ECD SPECT were performed to assess the cerebral blood flows. Any visible debris within the FilterWire was sent for histological/cytological analyses. RESULTS: Technical success was achieved all 25 cases. The mean pre-procedural stenosis was 89% (range 70-100%), and that immediately after stent placement was nearly 0%. With the exception of only one major stroke (1/25, 4%), no periprocedural complications were encountered. On the diffusion weighted images, new lesions were observed in four patients (4/25, 16%), but these were clinically silent. FilterWire-related transient spasm occurred in eight of the 25 procedures (32%). CONCLUSION: Carotid artery stenting, with FireWire distal protection, seems technically feasible, safe and effective in preventing procedural related embolic complications.