Gadolinium-enhanced magnetic resonance angiography of renal transplants

Our purpose was to investigate three-dimensional (3D) gadolinium-enhanced magnetic resonance angiography (Gd-MRA) in the evaluation of renal transplant arteries. Eleven MR angiography examinations were performed in nine renal transplant patients. Gd-MRA, three-dimensional phase contrast (3D-PC) post-gadolinium, and two-dimensional time-of-flight (2D-TOF) MR angiography were performed and independently reviewed by three vascular radiologists who, for each MR angiography sequence, separately graded occlusive disease in the ipsilateral iliac artery, the transplant artery anastomosis, and the transplant artery itself. The Gd-MRA and 3D-PC data were reviewed as maximum intensity projections (MIP) reconstructed in standard planes, and the 2D-TOF data were interpreted from source images. In addition, a single vascular radiologist prospectively interpreted the Gd-MRA and 3D-PC data together, hereinafter Gd/PC, from MIP reconstructions for each case. In all of these patients either surgical (n = 3) or angiographic studies (n = 8) were performed within 21 days following the MR examination, which served as a reference standard to determine sensitivity and specificity. The sensitivity/specificity for the detection of significant stenosis were as follows: Gd-MRA, 67/88; 3D-PC, 60.3/76.6; 2D-TOF, 47/81; and Gd/PC, 100/100. The kappa statistic (kappa) for interobserver agreement for the grading of stenoses by 2D-TOF, Gd-PC, and Gd-MRA was 0.48, 0.60, and 0.74, respectively. The percentage of all vascular segments seen well enough to grade (cumulative for all three observers) was 94%, 85%, and 79% for Gd-MRA, 3D-PC, and 2D-TOF, respectively. The combination of Gd-MRA and 3D-PC is a promising approach to the evaluation of transplant renal arteries.