[Angiography with magnetic resonance++ of the renal arteries: bidimensional versus tridimensional "time of flight" technique].

Twenty volunteers were examined by means of 2D and 3D time of flight (TOF) Magnetic Resonance angiography (MRA) of the renal arteries. The possible diagnostic applications of MRA were also evaluated in 6 patients with renovascular diseases. MRA examinations of the renal arteries were performed with a 1.5 T superconductive magnet (Magnetom Siemens) and circular body coil. Ten volunteers were studied with 3D FISP sequences (FA 25 degrees, TR 40 ms, TE 7 ms, ST 1 mm, Ma 256 x 256, FOV 500); the images were acquired on the axial plane and were rotated, in MIP and target MIP, on the axial (z) and sagittal (x) axes. The other 10 volunteers were studied with 2D FLASH sequences (FA 18 degrees, TR 300 ms, TE 8 ms, ST 4 mm, overlap 1 mm, Ma 256 x 256, FOV 500); the images were acquired on the axial and coronal planes and were rotated, in MIP and target MIP, on the axial (z) and sagittal (x) axes. The ostium and proximal segments (1-15 mm) were always easily identified with 2D and 3D sequences, the distal segments (16-35 mm) were also clearly demonstrated in 11 cases with 3D (55%) and in 16 cases with 2D (85%) sequences. The bifurcations and branch vessels of the renal arteries were easily depicted with 3D TOF sequences in 7 cases only. Combined 3D and 2D TOF images permitted the thorough evaluation of the renal arteries. In renovascular diseases, 2D and 3D TOF images clearly demonstrated occlusions and stenoses of the proximal segment (1-15 mm). 2D TOF sequences only permitted the visualization of a case of fibromuscular dysplasia in the distal segment. Our results suggest that 2D and 3D TOF MRA exhibits good potentials as a noninvasive screening technique for the evaluation of renovascular diseases.