QUANTIFICATION OF RENAL TRANSPLANT PERFUSION AND FUNCTION BY TECHNETIUM-99M DIMERCAPTOSUCCINIC ACID SCINTIGRAPHY

P394 Aims: The purpose of our study was to evaluate whether the quantitative analysis of vascular transit and specific uptake of 99mTc-dimercaptosuccinic acid (DMSA) in the transplanted kidney could obtain useful clinical data about renal transplant perfusion and function. Methods: Two groups of patients in the early post-transplantation period were investigated. Group A consisted of 10 patients with well-functioning transplant and group B of 10 patients with suspected acute rejection. Additionally, control group (C) of 23 potential kidney donors was established in order to define the normal values of fractional renal blood flow (RBF) and specific uptake of 99mTc-DMSA in renal tubular cells (RU). RBF was estimated from the derived first-pass activity plateau in renal region of interest, and expressed as a fraction of cardiac output. For the calculation of RU, counting rates acquired during 99mTc-DMSA scintigraphy were used. RU was expressed as a fraction of injected radioactive dose. Results: Control group (C) shown normal values of RBF: 0.208±0.036 for both kidneys (0.110±0.028 for one kidney). Mean values of RBF in group A were 0.140±0.031. This was 53% higher than one kidney RBF and 23% lower than global RBF in group C. RBF in group B of 0.061±0.019 was 56% lower than in group A and 66.5% lower than global RBF in group C. (p<0.005). Mean values of RU in group C were 0.454±0.094 for both kidneys (0.227±0.077 for one kidney). Both groups of patients with transplanted kidney showed significantly lower values of RU: 0.162±0.039 (group A) and 0.065±0.021 (group B). RU in group B was 28% lower than in group C. RU in group B was 71% lower than in group C and 60% lower than in A. Results of RBF and RU were correlated with blood urea nitrogen (BUN), serum creatinine (Cr) and creatinine clearance (CCr). Significant correlation was obtained: BUN/RBF r = − 0.70; Cr/RBF r = = 0.73; CCr/RBF r = 0.90; BUN/RU r = = 0.86; Cr/RBF r = = 0.77; CCr/RU r = 0.60. Conclusion: The results of our study indicated that RBF could be used as a sensitive parameter of renal transplant perfusion. The method of quantification gives physiological values of renal blood flow in healthy subjects. Well functioning transplant could receive a fraction of cardiac output that is similar to that to two normal kidneys. Flow to the rejecting allograft is markedly reduced. The estimation of RU gives additional quantitative information on cortical mass function of transplanted kidney. In patients with well-functioning transplant uptake was slightly reduced. Low values of RU in acute rejection were probably related to lesions in kidney blood vessels and in tubular cells.