Nonenhanced Free-Breathing ECG-Gated Steady-State Free Precession 3D MR Angiography of the Renal Arteries: Comparison Between 1.5 T and 3 T

OBJECTIVE. The purpose of our study was to compare the image quality of free-breathing ECG-gated nonenhanced steady-state free precession (SSFP) MR angiography of renal arteries at 1.5 T and 3 T. SUBJECTS AND METHODS. Twenty volunteers (11 men, nine women; mean age, 23.2 +/- 2.3 years) without a history of renovascular disease participated in the study. Nonenhanced SSFP MR angiography was performed on all subjects at both 1.5 T and 3 T with a maximum interval of 2 weeks between the imaging sessions. The subjective image quality of axial and coronal maximum-intensity-projection reconstructions of four segments (1, abdominal aorta and ostium of renal artery; 2, main renal artery; 3, segmental branches outside renal parenchyma; 4, segmental branches inside renal parenchyma) was evaluated independently by two radiologists using a 4-point scale (4, excellent; 1, nondiagnostic). Relative signal-to-noise ratio, contrast-to-noise ratio, and maximum visible vessel length of the right and left renal arteries also were determined. RESULTS. No significant difference in image quality at 1.5 T and 3 T was found for segments 1 and 2. The mean image quality for segments 3 and 4 was significantly greater at 3 T (3.88 +/- 0.32, 3.17 +/- 0.70) than at 1.5 T (3.32 +/- 0.73, 2.09 +/- 0.81) (p < 0.001). At 3 T, the maximal vessel length of the right (9.85 +/- 0.82 cm) and left (8.3 +/- 0.79 cm) renal arteries was significantly greater than at 1.5 T (8.94 +/- 1.38 cm and 7.58 +/- 1.18 cm, respectively). CONCLUSION. Performing nonenhanced SSFP MR angiography at 3 T significantly improves visualization of peripheral renal arterial segments in healthy subjects as compared to 1.5 T.