Evaluation of renal graft function with radionuclide dynamic images--with special reference to the application of the modified Rutland's analytical method

Abstract

In calculation of an uptake coefficient (UC), proportional to the glomerular filtration rate for renal dynamic images with 99mTc diethyl triamine pentaacetate (DTPA), by the graphic method proposed by Rutland. We developed a new method of estimating input and output functions, by applying a factor analysis method to the renal dynamic images. The purposes of this paper are to describe the results obtained through phantom experiments and its clinical application. In the phantom experiments, a hemofilter was used as a method for real kidney and the filtration rate was changed to estimate the reproducibility of UCs. the UCs were estimated by trying different input functions; abdominal aorta curve, renal artery curve and intrarenal artery curve. The UCs estimated by using the intrarenal artery curve as an input function showed the best correlation with the pre-determined filtration rate. In clinical applications 8 normal subjects, 3 patients with acute renal failure, 11 donors and 22 recipients were studied. The USs obtained were compared with clinical data of renal function. A group of subjects having with both kidneys in the normal body space were classified as Cluster 1, another group of transplant recipients were classified as Cluster 2. In Cluster 1 the UCs showed a good correlation with Ccr (r = 0.909), and effective renal plasma flow (r = 0.798), and an inverse correlation between UCs and serum creatinine values (r = 0.747). The median value of UCs in 11 donors at pretransplantation were 0.30, which increased to 0.46 at 3 weeks after transplantation. Cluster 2 has many risk factors (to be abnormal space, rejection, toxicity of Cyclosporin and immuno suppression) compared to Cluster 1, but in Cluster 2 the UCs showed a good correlation with Ccr (r = 0.955), and effective renal plasma flow (r = 0.653), and an inverse correlation between UCs and serum creatinine values (r = 0.857). Cluster 1 and Cluster 2 showed the same correlations with Ccr and UCs. But Cluster 1 is a different group from Cluster 2. The results of the study showed that the modified Rutland's analy analytical method can estimate the renal filtration rate accurately, evaluate the residual renal function in donors quantitatively and be a useful parameter for monitoring renal graft function.