Diffusion-Weighted Imaging and Diffusion Tensor Imaging Detect Delayed Graft Function and Correlate With Allograft Fibrosis in Patients Early After Kidney Transplantation

Purpose: To combine diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for detection of allograft dysfunction in patients early after kidney transplantation and to correlate diffusion parameters with renal function and renal histology of allograft biopsies. Materials and Methods: Between day 4 and 11 after kidney transplantation 33 patients with initial graft function and 31 patients with delayed graft function (DGF) were examined with a 1.5T magnetic resonance imaging (MRI) scanner. DTI and DWI sequences were acquired and fractional anisotropy (FA), apparent diffusion coefficient (ADCmono), pure diffusion (ADC(diff)), and the perfusion fraction (Fp) were calculated. Kidney biopsies in 26 patients were analyzed for allograft pathology, ie, acute tubular injury, inflammation, edema, renal fibrosis, and rejection. Histological results were correlated with MRI parameters. Results: In the renal medulla FA (0.25 +/- 0.06 vs. 0.29 +/- 0.06, P < 0.01) and ADCmono (1.73 +/- 0.13(star)10(-3) vs. 1.93 +/- 0.16 star 10(-3) mm(2)/s, P < 0.001) were significantly reduced in DGF patients compared with patients with initial function. For ADC(diff) and Fp similar reductions were observed. FA and ADCmono significantly correlated with renal function (r=0.53 and r=0.57, P < 0.001) and were inversely correlated with the amount of renal fibrosis (r=-0.63 and r=-0.65, P < 0.05). Conclusion: Combined DTI and DWI detected allograft dysfunction early after kidney transplantation and correlated with allograft fibrosis.