High resolution contrast-enhanced 3D MR-angiography of renal arteries using parallel imaging (SENSE)

Purpose: To compare three dimensional contrast enhanced MR angiography with parallel imaging technique (sensitivity encoding) to standard MR angiography technique. Material and Methods: CE-3D MRA of renal arteries was performed in 22 patients (23 examinations) on a 1.5 T MR- scanner (Gyroscan Intera, Philips, Netherlands). For contrast enhanced MRA a single dose of Gd-DTPA (0.1 mmol/kg b.w.) was administered. Group 1: The following standard 3D gradient echo (GE) sequence was performed in 9 of the 22 patients: TR: 4.3 ms, TE: 1.5 ms, flip,angle: 40, 40 slices, scan duration: 19 seconds. A spatial resolution of 1.96 x 1.76 x 3.0 mm(3) (1.76 x 1.76 x 1.5 mm(3) interpolated) was obtained. Group 11: 14 examinations were acquired in 13 patients: TR, TE and flip angle were equal compared to the first protocol. The k-space lines were acquired with CENTRA (contrast-enhanced time robust angiography) and parallel-imaging technique (SENSE). 60 slices were acquired, scan duration was 24 seconds. The spatial resolution of this sequence was 1.19 x 1.08 x 2.0 mm(3) (0,84 x 0,84 x 1,0 mm(3) interpolated). Original images and calculated maximum intensity projection (MIP) images were analysed by two radiologists. Image quality and the visibility of renal arteries were rated on a four-point scale. Results: In the first group the image quality was rated "good" in 8/9 patients. The renal arteries were detected in all cases and rated "good". The anterior and posterior segments were rated,,good" in only 5/9 and the lobar arteries were detectable only in 3 of 9 cases. The interlobar arteries could not be seen in these patients. In the second group the image quality was rated excellent in 5 examinations and good in 9 of 14 examinations. The rating for the renal arteries was excellent in all examinations (14/14). The results of the anterior and posterior segment were as followed: excellent 5/14, good 7/14, insufficient 2/14; the lobar arteries: good 6/14, insufficient 6/14 and not detectable 2/14. Interlobar arteries could be seen in 7/14 examinations, but the quality was insufficient. In 7/ 14 the interlobar arteries could not be detected. Conclusion: The use of parallel imaging technique improves image quality and the delineation of small vessels in renal MRA.