Time-of-flight MR angiography of kidney transplants

The aim of the study was to apply time-of-flight MR angiography to renal transplant arteries with comparison of two- and three-dimensional (2D and 3D) sequences and to correlate the findings with colour flow sonography (CFS) and digital subtraction angiography (DSA). A total of 102 MR studies were performed in 101 patients: 87 with the 2D-FLASH sequence (18 repeated after Gd-DOTA administration), 49 with the 3D-FISP (both in 34). All patients were also studied with CFS and 15 with intra-arterial DSA. The 3D sequence produced good-quality MR angiograms in 94% of cases (82% in 2D). Gd-DOTA infusion improved the quality of the 2D angiograms in 7 of 18 cases. Only these patients were included in the remainder of the evaluation (90 patients with 103 arteries). CFS showed 72 normal and 10 abnormal arteries. In this group, the 2D sequence led to 7 (12%) false positives of stenosis and the 3D sequence yielded 1 (3%). Correlation between MR angiography and DSA was obtained for 21 arteries (15 patients) with suspicion of arterial complications. The 2D-FLASH (n = 13) and the 3D-FISP (n = 12) MR sequences allowed the correct diagnosis of all main artery complications (14 stenoses and 4 thromboses) without any false negatives and without discordance when both sequences were performed (n = 4). In the 3 other cases with a normal main artery, 2 segmental thromboses were correctly identified by both sequences and 1 stenosis of a segmental branch was correctly identified by the 2D sequence only but misdiagnosed as a thrombosis with the 3D sequence. Grading of the severity of stenoses was inaccurate with both sequences. It is concluded that the 3D time-of-flight MR sequence provides better MR angiograms than the 2D, with fewer false positives for stenosis. No false-negative arterial complications were noted.Correspondence to: N. Grenier