Magnetic Resonance With Diffusion-Weighted Imaging in the Evaluation of Transplanted Kidneys: Preliminary Findings

Background. The aim of this study was to compare values of apparent diffusioncoefficient (ADC) and diffusion (D) with renal function indexes, in a population of kidneytransplant recipients who underwent magnetic resonance with diffusion-weighted imaging(DWI) of the transplanted graft.Materials and Methods. We studied 21 patients using a 1.5-Tesla magnetic resonance;DWI sequences were acquired with several b-values. Patients were divided into 3 groupsby their creatinine clearance values: group A, clearance 60 mL/min; group B, clearance30 and 60 mL/min; and group C, clearance 30 mL/min. ADCs values between groupswere compared using the Mann–Whitney U test. Receiver operating characteristic (ROC)curves were created for prediction of normal renal function (group A) and renal failure(group C).Results. Comparing mean values of ADC between groups A and C, we observed adifference (P 0.0012), with higher values in group A. Regarding mean values of D, weobserved a difference between groups A and C (P 0.022). In the comparison betweencontiguous groups, we observed no difference for ADC and D values. In the prediction ofnormal clearance values (group A), ROC curve showed an area under curve (AUC) of0.861, with a sensitivity of 88.89% and specificity of 75% using a threshold ADC value2.1 103 mm2/sec. For prediction of normal clearance values (group A), ROC curveshowed an AUC of 0.787, with a sensitivity of 77.8% and specificity of 83.3% using athreshold D value 2.3 103 mm2/sec.Conclusion. Although studies with a larger number of patients are needed, DWIrepresents a promising tool for noninvasive assessment of renal function. An ADC 2.1 103 mm2/sec and a D 2.3 103 mm2/sec may be used as a threshold for predictingnormal clearance.