3-DIMENSIONAL MAGNETIZATION-PREPARED TIME-OF-FLIGHT MR-ANGIOGRAPHY OFTHE CAROTID AND VERTEBRAL ARTERIES

Three-dimensional magnetization-prepared (MP) MR angiography (MRA) was applied to the carotid and vertebral arteries by using ECG triggering , a slab selective RF inversion pulse, centric phase encoding and acqu isition during diastole. Both theoretically and experimentally, the MP MRA sequence was shown to perform well in cases where there was subst antial blood replenishment during the inversion time Tl (>330 ms). In comparison with standard, ungated, steady-state 3D time-of-flight MRA in 13 consecutive volunteers, the MP MRA images demonstrated better ba ckground suppression with less artifact and generally had more uniform vessel depiction. The MP MRA sequence was generally superior for port raying vessels exhibiting high pulsatility such as the carotid siphon. However, in distal vessels with slow flow and incomplete blood replen ishment, the MP MRA technique was inferior due to increased loss of ve ssel signal. The reasons for this increased signal loss are identified and improvements to the MP MRA sequence are suggested.