Magnetic resonance imaging of renal transplants: its value in the differentiation of acute rejection and cyclosporin A nephrotoxicity.

The purpose of this study was to determine the value of magnetic resonance imaging (MRI) in the differentiation of acute rejection and cyclosporin A nephrotoxicity in renal transplant kidneys. Fifty-six magnetic resonance examinations in 46 patients were prospectively and independently evaluated by two radiologists. MRI was performed with a 0.5 T superconducting scanner (Gyroscan S5, Philips) applying both T1 and T2 weighted pulse sequences. Biopsies were performed in 22 cases and histology was reviewed. Fifteen normally functioning transplant kidneys and 41 kidneys with graft dysfunction due to cyclosporin A nephrotoxicity, acute rejection, chronic rejection or acute tubular necrosis were studied. Absence or reduction in cortico-medullary demarcation proved to be a sensitive, but non-specific indicator of parenchymal disease. In cases of cyclosporin A nephrotoxicity the allograft was diagnosed as being normal in 90%. The magnetic resonance appearance of acute rejection may be very similar to that of the combination of acute rejection and cyclosporin A nephrotoxicity, chronic rejection or acute tubular necrosis. However differentiation between acute rejection and cyclosporin A nephrotoxicity was possible according to the following statistical data: sensitivity 100%, specificity 75%, positive predictive value 86%, negative predictive value 100%, accuracy 90%.