[Magnetic resonance angiography at 0.5 Tesla of the renal arteries. Capabilities and limitations of the 2-dimensional phase contrast technique].

To investigate the potentials and limitations of Magnetic Resonance Angiography (MRA) of the renal arteries at mid-field strength, 16 patients with arterial hypertension of suspected renovascular origin were submitted to MRA at 0.5 T with the two-dimensional (2D) phase-contrast technique and to arteriography. MRA yielded diagnostic images in 15 (94%) patients in whom MRA and arteriography identified 38 and 39 renal arteries, respectively. MRA sensitivity and specificity to steno-occlusive alterations of the renal arteries demonstrated by arteriography were 83% and 96%, respectively. These results, although obtained in a small group of patients, indicate that MRA of the renal arteries with a mid-field MR system and the 2D phase-contrast technique can allow the diagnosis of steno-occlusive alterations of the renal arteries. Main MRA limitations were its long acquisition time and some variability in the quality of the MRA images. Nevertheless, the ongoing rapid technical developments in the hardware of MR systems leave room for improving the accuracy of mid-field MRA of the renal arteries and justifies optimism as to its role in the screening of renovascular hypertension.