Magnetic Resonance With Diffusion-Weighted Imaging in the Evaluation of Transplanted Kidneys: Updating Results in 35 Patients

Background. We compared values of apparent diffusion coefficient (ADC) with renal function indices among a population of kidney transplant recipients who underwent magnetic resonance with diffusion-weighted imaging (DWI) of their grafts.Materials and Methods. Thirty-five patients with right iliac transplanted kidneys were studied using 1.5-T magnetic resonance. Diffusion echo-planar sequences with several b-values were acquired to investigate transplanted grafts. Patients were divided into 3 groups accordingto their creatinine clearances; Group A, clearance 60 mL/min; Group B, clearance 30 and 60 mL/min; and Group C, clearance 30 mL/min. ADC values between groups were compared using Mann-Whitney U test. Receiver operating characteristic (ROC) curves were used to predict the normal function (Group A) versus renal failure cohorts (Group C).Results. Comparing mean values of ADC between Group A and Group C patients, we observed a significant difference (P .0003) with higher ADC values among patients with a normal creatinine clearance (60 mL/min). Comparing Groups B and C did not show a significant difference (P .05); nor did Group A and Group B reveal a significant difference (P .38). To predict normal clearance values, the Group A ROC curve showedan area under curve (AUC) of 0.780 with a sensitivity of 92.3% and a specificity of 68.2% at a threshold ADC value of 2.08 103 mm2/sec. In the prediction of low clearance values, the Group C ROC curve showed an AUC of 0.846 with a sensitivity of 83.3% anda specificity of 82.6% using a threshold ADC value of 2.07 103 mm2/sec.Conclusions. Updating our experience among 35 patients, DWI was confirmed to be a promising noninvasive tool to assess renal function; an ADC 2.08 103 mm2/sec may be used as a threshold to predict a normal clearance. However, an overlap of ADC values between groups is a limit.