[Magnetic resonance angiography of the intracranial vessels. Technique and anatomy].

Fifty volunteers were studied by means of MR angiography of the intracranial vessels, with a 1.5 T Siemens Magnetom. The technical features of the most employed MR angiographic techniques were analyzed. The inflow technique was tested with refocused gradient-echo sequences for the FISP 3DFT flow and a dedicate coil. The study was aimed at evaluating the resolution power of each technique and at identifying the most useful rotations and angles for each chosen vessels. The acquisition volume of the gradient-echo sequence was positioned on the axial plane with sella turcica in the center. TR was set at 0.04 s, TE at 10 ms, and flip angle was 15 degrees. A 256 x 256 matrix was used, and an 80-mm acquisition volume, with 64 partitions. The chosen images were rotated on the axial and sagittal planes 0 degrees-180 degrees. The results showed that both rotation planes and their relative angles allow the visualization of all the vessels. To reduce post-processing time, with immediate availability of computer keyboard, a standardization is suggested with 0 degrees-180 degrees rotations on the axial plane, with 15 degrees interval and 0 degrees-45 degrees rotations on the sagittal plane, with 15 degrees interval. The main limitation of this method is its spatial resolution, which was 1.2 mm in rotations and acquisitions on the axial plane and 1 mm in acquisitions on the axial plane rotated on the sagittal plane.