Intracranial MR angiography: comparison of single-volume three-dimensional time-of-flight and multiple overlapping thin slab acquisition techniques.

Abstract

Time-of-flight (TOF) MR angiography has continued to evolve during the past few years. Signal loss due to flow saturation is a major problem of single-volume (slab) three-dimensional (3D) TOF technique. A multislab 3D TOF method, multiple overlapping thin slab acquisition (MOTSA), shows decreased sensitivity to the effects of flow saturation and therefore should result in better images. To evaluate the difference between MOTSA and the traditional single-volume 3D TOF techniques, we performed sequential, location-matched studies in 17 prospectively chosen patients with intracranial vascular abnormalities. All MOTSA and 3D TOF images were obtained after cut-film or 1024 digital angiography. According to specific criteria, abnormalities were better visualized with the MOTSA technique than with the single-volume 3D TOF technique. The difference was most marked in patients with more complex vascular abnormalities. We conclude that MOTSA is better than single-volume 3D TOF for showing intracranial abnormalities. The major advantage of MOTSA is decreased sensitivity to flow saturation.