Navigator-gated Non-contrast Renal MR Angiography : : Qualitative and Quantitative Comparison of 3T and 1.5T Images

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Purpose : The aim of this study was to compare non-contrast 3T renal MRA with that of 1.5T unit. Methods and Materials : We performed renal MRA in twelve volunteers using a 1.5T and 3T unit. For renal MRA, 3D SSFP sequence was used. For quantitative evaluation, ROI was set on the aorta, main stems of bilateral renal arteries, and IVC, measuring flow signal at each point. Signal intensity ratio (SIR) of renal artery relative to the parenchyma and IVC were calculated. For subjective analysis, two readers evaluated visual quality. Results : SIR of the both renal artery on 3T MRA were significantly higher than those on 1.5T (p<0.01). On subjective analysis, the mean visualization score of renal main stem showed no statistically significant difference. However, the scores of the peripheral branches on 3T was significantly higher than those of 1.5T bilaterally (p<0.05). IVC showed significantly lower signal ratio on 3T relative to that on 1.5T. Conclusion : 3T MRA showed superior demonstration of renal arteries compared with 1.5T MRA. The intraparenchymal peripheral branches are especially well demonstrated on 3T MRA. Decreased venous signal on 3T system contributed to the selective arterial demonstration.