Renal function after tumor enucleation: Assessment by quantitative SPECT of ^99mTc-dimercaptosuccinic acid uptake by the kidneys

The purpose of this study was to evaluate the amount of functioning renal mass removed and the amount of remaining individual renal function after tumor enucleation. Methods: Renal functional volume, percentage injected dose (%ID) per cubic centimeter of renal tissue and individual renal uptake of 24 operated and 24 contralateral kidneys were studied by two sequential SPECT quantitations of ^99mTc-dimercaptosuccinic acid (DMSA) uptake by the kidneys (QDMSA). The first study was before surgery and the second study was 1 to 6 mo (mean 3.5 mo) after surgery. Mean tumor size was 3.4 ± 0.99 cm and all tumors were confined to the renal parenchyma (stages pT1 and pT2). Results: In the operated kidneys, there was a statistically significant decrease in renal cortical volume (170 ± 46 mL after surgery versus 207 ± 45 mL before surgery, t = 6.2, P < 0.001) and individual renal uptake (10.3% ± 3.0% after surgery versus 13.0% ± 2.9% before surgery, t = 5.4, P< 0.001). There was no statistically significant change after surgery compared with before surgery in the %ID per cubic centimeter of renal tissue of the operated kidneys, and in the volume, %ID per cubic centimeter and uptake of the contralateral normal kidneys. Conclusion: The results suggest that QDMSA is a noninvasive method able to assess changes in separate renal function. The limited functioning parenchymal loss after tumor enucleation had no effect on the opposite kidneys.