Fat suppression in combination with multiple overlapping thin-slab 3-D acquisition MR angiography: proposed technique for improved vessel visualization.

PURPOSE To study the parameters of the 1331 fat saturation pulse (saturation pulse flip angle (SPFA) and interpulse delay (tau)) in order to identify values that provide optimal vessel visibility. METHODS Carotid bifurcations of three healthy subjects were studied. RESULTS The optimal values for the SPFA and tau were 60 degrees (7.5 degrees, -22.5 degrees, 22.5 degrees, -7.5 degrees) and 2.0-3.0 msec, respectively. At these values there was a 1.56-fold increase (SD = +/- .12, P less than .01) in the contrast-to-noise ratio between the left internal carotid artery and fat compared to the study without fat saturation. A 3.0-fold increase was noted for the smaller left occipital artery. Additionally, there was no statistically significant reduction in the vessel-muscle contrast-to-noise ratio nor in the absolute vessel signal-to-noise ratio at these values. CONCLUSION Implementation of fat saturation into carotid MR angiography markedly improves visualization of vascular anatomy without increasing imaging time.