INTRACRANIAL VASCULAR STENOSIS AND OCCLUSION - MR ANGIOGRAPHIC FINDINGS

PURPOSE: To investigate whether obtaining axial source images from thr ee-dimensional Fourier transform (3DFT) time-of-flight MR angiography improves the detection of intracranial Vascular stenosis and occlusion if added to maximum-intensity projection (MIP) images. METHODS: The a ngiograms of 103 patients who had MR angiography for evaluation of pos sible intracranial Vascular disease were reviewed retrospectively in a quantitative and nonquantitative fashion. Diameters of vessels on MR angiograms were measured quantitatively by two reviewers using a magni fying loupe and compared with the results from conventional angiograms . Degrees of stenoocclusive disease were categorized into five classes ; an artery with stenosis of 50% or greater was considered to be disea sed. Another five observers also reviewed the MIP images with and with out source images in a blinded fashion by means of nonquantitative vis ual inspection. RESULTS: In all, 23 stenoocclusive lesions of 50% or g reater were available for review. In the quantitative analysis, with M IP images alone, 14 (78%) of 18 moderate and severe stenoses and four (80%) of five occlusions were identified correctly. The addition of th e source images increased the sensitivity to 100% for moderate and sev ere stenoses and to 100% for occluded vessels. In the visual inspectio n study, however, no statistically significant differences were found between interpretations of Mm images alone and those of MIP images in combination with source images. CONCLUSION: In the quantitative study, interpretation of source images rather than MIP images reduced the te ndency to overestimate stenosis seen with MR angiography and improved the sensitivity for detecting stenosis of 50% or greater. There was a discrepancy between the quantitative study and visual inspection. Expe rienced observers had a tendency to underestimate the degree of stenos is.