Evaluation of renal allograft dysfunction using 99mTc-DTPA dynamic SPECT. Analysis with two compartment model and graph plot

To estimate renal blood flow and glomerular function in transplanted kidneys, we applied the 2 compartment model and the graphic analysis method to 99mTc-DTPA dynamic SPECT and calculated some parameters, i.e. K1 (renal influx rate constant), K3 (glomerular filtration rate constant), Vdl (function phase distribution volume), and others. Twenty-three renal transplant recipients were examined and divided into following 3 groups according to their serum creatinine levels (SCr); Group I; less than 1.3 mg/dl (1.1±0.3, n=7), Group II: 1.4-2.5 mg/dl (1.8±0.3, n=7), and Group III more than 2.6 mg/dl (4.8±2.9, n=5). The K3 value became lower in the order of Group I>II>III, and well correlated with blood urea nitrogen (BUN, r=<0.91, P<0.001) and creatinine clearance (Ccr, r=0.87, P<0.001). The K1 value reduced markedly in Group III despite or no difference between Group I and II. Glomerular filtration rate (GFR) derived from K1 and K3 showed a correlation with those by Tauxe's method. From these results and clinical conditions including histopathological findings, it is suggested that K1, K3 and Vdl are useful paraments of renal central arterial blood flow, renal peripheral arteriolar blood flow and renal 99mTc-DTPA uptake function, respectively. (author)