Tc-99m-DMSA Renal Uptake Rate and Renal Volume of Elderly Persons

Measurement by SPECT Renal Tomographic Image

Abstract

Renal function of erderly persons was evaluated by the radionuclide renal function test based on the renal uptake rate and the renal volume determined by Tc-99m-DMSA transectional tomographic images using single photon emission computed tomography (SPECT). Forty-three erderly cases (13 healthy persons and 30 patients with various types of renal disorders) aged between 60 and 87 on an average of 70 were studied and compared with results obtained from 20 healthy adults (18-45 years old). Renal volume was calculated from the summation of voxels in the region districted by equi-count threshold level (percentage to maximum count) on each section of the SPECT image. Attenuation correction was made by GE-STAR protocol utilizing Sorrenson's precorrection method. The renal uptake rate was expressed as a percentage of the total radioactivity detected within the renal volume, against an amount of dose injected. In the 26 kidneys of 13 healthy elderly persons, Tc-99m-DMSA renal uptake was 23±5%, which was signifficantly lower (p<0.01) than that of healthy adults being 27±2%. A correlation coefficient between renal volume and uptake of 79 kideys of 43 elderly persons was 0.5081 (p<0.01). Creatinine clearance (Ccr) was better correlated with the total renal uptake (r=0.6471, p<0.01) than with the total renal volume (r=0.3592, p<0.01). This method is considered to be useful for clinical purpose as a test of renal function for elderly persons since it requires neither blood nor urine samples.