Multiparametric magnetic resonance imaging shows promising results to assess renal transplant dysfunction with fibrosis

Here we assessed the diagnostic value of a quantitative multiparametric magnetic resonance imaging (mpMRI) protocol for evaluation of renal allograft dysfunction with fibrosis. Twenty-seven renal transplant patients, including 15 with stable functional allografts (eGFR mean 71.5 ml/min/1.73m(2)), and 12 with chronic dysfunction/established fibrosis (eGFR mean 30.1 ml/min/1.73m(2)), were enrolled in this prospective single-center study. Sixteen of the patients had renal biopsy (mean 150 days) before the MRI. All patients underwent mpMRI at 1.5T including intravoxel-incoherent motion diffusion-weighted imaging, diffusion tensor imaging, blood oxygen level dependent (BOLD R-2*) and T-1 quantification. True diffusion D, pseudodiffusion D*, perfusion fraction PF, apparent diffusion coefficient (ADC), fractional anisotropy (FA), R-2* and T-1 were calculated for cortex and medulla. Delta T-1 was calculated as (100x(T-1 Cortex-T-1 Medulla)/T-1 Cortex). Test-retest repeatability and inter-observer reproducibility were assessed in four and ten patients, respectively. mpMRI parameters had substantial test-retest and interobserver repeatability (coefficient of variation under 15%), except for medullary PF and D* (coefficient of variation over 25%). Cortical ADC, D, medullary ADC and Delta T-1 were all significantly decreased, while cortical T-1 was significantly elevated in fibrotic allografts. Cortical T-1 showed positive correlation to the Banff fibrosis and tubular atrophy scores. The combination of Delta T-1 and cortical ADC had excellent cross-validated diagnostic performance for detection of chronic dysfunction with fibrosis. Cortical ADC and T-1 had good performance for predicting eGFR decline at 18 months (4 or more ml/min/1.73m(2)/year). Thus, the combination of cortical ADC and T-1 measurements shows promising results for the non-invasive assessment of renal allograft histology and outcomes.