Carotid bifurcation: Evaluation of time-resolved three-dimensional contrast-enhanced MR angiography

A magnetic resonance (MR) angiographic protocol was evaluated in the caroti d bifurcation with use of a pulse sequence for time-resolved three-dimensio nal imaging of contrast material kinetics. The enhancement ratio, a quantit ative measure of contrast enhancement, indicated that all studies included an image obtained near the peak of the intraarterial concentration of contr ast agent (enhancement ratio, 90% +/- 9 [standard deviation]). Studies acqu ired at a higher frame rate (4.1-4.9 seconds) exhibited less venous enhance ment (enhancement ratio, 25% +/- 16) than studies acquired with slower (6.0 -9.6-second) frame rates (enhancement ratio, 46% +/- 25).