Work

Imaging of the renal allograft vasculature without gadolinium contrast: Intraindividual comparison between relaxation-enhanced angiography without contrast and triggering (REACT) and 4D contrast-enhanced MR-angiography

Year: 2025

Type: article

Abstract: BACKGROUND: Complications after kidney transplantation include transplant renal artery stenosis (TRAS), which can be assessed using Doppler ultrasonography, computed tomography angiography, and magnetic resonance angiography (MRA). Contrast-enhanced MRA (CE-MRA) has limitations, including potential allergic reactions, limited use in kidney failure, and uncertain long-term effects of gadolinium retention. PURPOSE: To evaluate Relaxation-Enhanced Angiography without Contrast and Triggering (REACT), a novel 3D isotropic flow-independent non-CE-MRA pulse sequence, for imaging of the renal allograft vasculature by performing an intraindividual comparison to 4D CE-MRA at 3Tesla. METHODS: Forty studies of 39 patients were included in this retrospective, single-centre study. Two board-certified radiologists independently evaluated MRA datasets for TRAS and rated their diagnostic confidence and the image quality of pelvic vessels using 5-point Likert scales (5 = excellent). Apparent signal- and contrast-to-noise ratios (aSNR/aCNR) were measured for arterial and venous graft vessels. RESULTS: REACT (median acquisition time 04:33 min [IQR 3:58-5:20 min]) showed 90.0 % sensitivity and 100.0 % specificity for TRAS in almost perfect agreement (r = 0.97) with 4D CE-MRA (03:41 min [3:38-4:46 min], p = 0.001) and similar diagnostic confidence (REACT: 4.0 [4.0-4.0] vs. 4D CE-MRA: 4.0 [3.0-4.0], p = 0.54). Arterial image quality was comparable (4.0 [3.7-4.4] vs. 4.0 [4.0-4.4], p = 0.49) whereas veins yielded higher scores in REACT (3.2 [3.0-3.5] vs. 2.4 [2.0-3.0], p < 0.001). Transplant renal artery (mean ± SD; 44.5 ± 18.2 vs. 45.9 ± 21.0, p = 0.71; 36.3 ± 15.0 vs. 41.0 ± 20.0, p = 0.16) and vein (37.1 ± 19.8 vs. 30.3 ± 15.2, p = 0.06; 29.4 ± 17.1 vs. 25.0 ± 14.7, p = 0.17) showed no difference in aSNR and aCNR. CONCLUSION: REACT provides accurate detection of TRAS with image quality comparable to 4D CE-MRA, offering a risk-free alternative for imaging after renal transplantation.

Source: Magnetic Resonance Imaging

DOI: 10.1016/j.mri.2025.110423