Renal arteries: Optimization of three-dimensional gadolinium-enhanced MR angiography with bolus-timing-independent fast multiphase acquisition in a single breath hold

PURPOSE: To compare two different three-dimensional (3D) gadolinium-enhance d magnetic resonance (MR) angiographic techniques. MATERIALS AND METHODS: In 26 patients suspected of having renal artery sten osis, results with fast multiphase 3D MR angiography were compared to those with standard 3D MR angiography in 37 patients. With both techniques, 31-s econd breath-hold acquisitions were Performed. Multiphase angiography compr ised five discrete 6.4-second acquisitions without bolus timing, and standa rd angiography comprised a single acquisition based on test-bolus timing. T wo readers evaluated images obtained with both techniques in terms of image quality, artifacts, and vessel conspicuity. Accuracy of findings on the mu ltiphase 3D MR angiograms for assessment of renal artery stenosis was deter mined by comparing them to digital subtraction angiograms and surgical find ings. RESULTS: In the early arterial phase, multiphase 3D MR angiograms showed no image degradation by venous overlay, whereas: standard 3D MR angiograms de picted at least minor overlay in 53 of 83 renal arteries (P < .001). Less p arenchymal enhancement in the early arterial phase resulted in a higher ves sel conspicuity for the divisions and segmental arteries(P < .001). Both re aders detected and correctly graded 18 of 20 stenoses on the multiphase ang iograms with almost perfect interobserver agreement (kappa > 0.89). CONCLUSION: Renal multiphase 3D MR angiography is an accurate technique req uiring no bolus timing. The performance of early arterial phase imaging lea ds to improved depiction, particularly of the distal renovascular tree,comp ared to that with standard single-phase 3D MR angiography.