Evaluation of dynamic contrast-enhanced MRI in detecting renal scarring in a rat injury model

Abstract

Purpose: To create a reliable rat model with small renal cortical scars and evaluate the accuracy and sensitivity of dynamic contrast-enhanced MRI in detecting the kinds of lesions that are associated with reflux nephropathy. Materials and Methods: In 16 rats, three unilateral renal cortical lesions were created using either electrocautery or pure alcohol with the contralateral kidney serving as control. MRI on a 1.5 Tesla GE Signa was performed 10-14 days after surgery. After bolus injection of 0.2 mM/Kg Gd-DTPA, sequential MRI acquisitions were performed using a 4-inch quadrature birdcage coil. Renal and scar volumes and pathology were compared after scanning and killing. Results: Of the 48 points of injury, 40 (83%) in the 16 rats were detected grossly. Under microscopy, 36 injuries (75%) were detected on mid-kidney cross-sections. The average lesion was 4.2 mm3 corresponding to 0.5% of the kidney volume. Using pathological findings as the gold standard, the sensitivity and specificity of scar detection using MRI was 69% and 93%, respectively. Conclusion: A rat model was created to demonstrate the sensitivity of dynamic contrast-enhanced MRI for detecting renal scars. Alcohol and electrocautery created reliable renal scars that were confirmed pathologically. MRI detected these lesions that averaged 4.2 mm3 (0.5% total renal volume) with sensitivity and specificity of 69% and 93%, respectively. © 2010 Wiley-Liss, Inc.