Intracranial MR angiography: application of magnetization transfer contrast and fat saturation to short gradient-echo, velocity-compensated sequences.

Abstract

To circumvent artifacts related to saturation, turbulence, and data processing in three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography, the authors used a high-resolution (256 x 512), short, asymmetric velocity-compensated gradient-echo sequence, magnetization transfer contrast (MTC) between all excitation pulses to suppress brain parenchyma signal, and frequency-offset fat saturation (FS) to suppress fat signal. Signal intensity and blood-background contrast was measured in several regions of interest on conventional 3D TOF MR images, MTC images, and those with MTC and FS in seven volunteers. One patient each with an arteriovenous malformation, an aneurysm, and stenosis in the intracranial vascular system underwent the protocols with an echo time (TE) of 5 msec and then a TE of 8 msec. Use of the 5-msec-TE sequence with MTC and FS led to reduced problems associated with signal void in areas of fast flow in patients. In volunteers and patients, vascular visualization was superior to that of current 3D TOF techniques.