Evaluation of allograft perfusion by radionuclide first-pass study in renal failure following renal transplantation.

To assess the diagnostic value of indices measured on a first-pass curve, we performed 72 radionuclide renal first-pass studies (RFP) in 21 patients during the early weeks following renal allograft transplantation. The diagnosis was based on standard clinical and biochemical data and on fine needle aspiration biopsy (FNAB) of the transplant. Aortic and renal first-pass curves were filtered using a true low-pass filter and five different indices of renal perfusion were computed, using formulae from the literature. Statistical analysis performed on the aortic and renal indices indicated excellent reproducibility of the isotopic study. Although renal indices presented a rather large scatter, they all discriminated well between normal and rejection. Three indices have a particularly good diagnostic value. In the discrimination between rejection and Acute Tubular Necrosis (ATN), only one index gave satisfying results. The indices, however, indicate that there are probably ATN with an alternation of renal perfusion and rejection episodes where perfusion is almost intact. We conclude that radionuclide first-pass study allows accurate and reproducible quantitation of renal allograft perfusion. The measured parameters are helpful to followup the course of a post-transplantation renal failure episode and to gain more insight into renal ischemia following transplantation.