3D contrast-enhanced MR angiography of the run-off vessels: Value of imagesubtraction

The diagnostic gain associated with image subtractions was assessed regardi ng contrast-enhanced 3D magnetic resonance angiography (MRA) Image sets of the pelvic and lower extremity arteries. The RUM strategy combined a dedica ted vascular coil with a single injection, two-station protocol. Voxel-by-v oxel signal intensity subtraction was performed on MRA image sets obtained before and during dynamic infusion of a para-magnetic contrast agent. Nonsu btracted and subtracted MRA image sets were assessed for the presence of oc clusive (four grades) disease, using DSA as the standard of reference. In a ddition, SNR and CNR were recorded for each vascular segment on both the no n-subtracted and subtracted images. While CNR values of subtracted Images e xceeded those of non-subtracted Images (P < 0.05), there was no difference in diagnostic performance. For the detection of hemodynamically significant disease, non-subtracted and subtracted MRA provided overall sensitivity an d specificity of 90.2%/90.3% and 95.1%/95.6%, respectively. Concordance bet ween non-subtracted and subtracted MRA was excellent (Kappa = 0.86). (C) 20 01 Wiley-Liss, Inc.