PERIPHERAL VASCULAR TREE STENOSES - DETECTION WITH SUBTRACTED AND NONSUBTRACTED MR-ANGIOGRAPHY

PURPOSE: To compare subtracted and nonsubtracted gadolinium-enhanced m agnetic resonance (MR) angiography and cardiac-synchronized time-of-fl ight MR angiography for help in detecting pelvic-region stenoses. MATE RIALS AND METHODS: Twenty-eight patients with intermittent claudicatio n underwent MR angiography with a 1.5-T system; two-dimensional cardia c-synchronized time-of-flight MR angiograms and three-dimensional MR a ngiograms (without and with gadolinium enhancement) were obtained. Sub tracted images were obtained by subtracting unenhanced data from enhan ced data of identical volumes, and maximum intensity projection images were constructed, which two observers independently evaluated in blin ded fashion, with conventional angiographic results as the reference s tandard. RESULTS: Sensitivity and specificity for grading of hemodynam ically significant stenoses (greater than or equal to 50% lumen reduct ion) on subtracted MR angiograms were 94% and 93%, respectively. Sensi tivity of subtracted images was significantly higher compared with tha t of time-of-flight images (P < .05) but not with that of nonsubtracte d images. Contrast-to-noise ratio on subtracted images was significant ly higher compared with that on nonsubtracted images (P < .05) but not with that on time-of-flight images. There was good correlation betwee n stenosis length measurements on gadolinium-enhanced MR angiograms an d those on conventional angiograms. CONCLUSION: Subtracted MR angiogra phy is superior to cardiac-synchronized time-of-flight MR angiography for imaging of iliac and upper femoral arteries and provides higher co ntrast-to-noise ratio, fewer artifacts, and easier image interpretabil ity than nonsubtracted MR angiography.