99mTechnetium penicillamine scans: an index of differential renal function.

The relative renal accumulation of 99mtechnetium penicillamine was evaluated as an index of differential renal function. Regions of interest were assigned over each kidney with a computer and the renal uptake of 99mtechnetium penicillamine was determined. A simple background correction was made by subtracting the renal activity at 10 minutes from that at 25 minutes. The percentage of 99mtechnetium penicillamine accumulation in the left kidney was correlated with the percentage of the total effective renal plasma flow to the left kidney. Effective renal plasma flow was determined after the intravenous injection of 131 I hippuran using a highly sophisticated computerized technique that has been validated in patients by comparison with traditional split renal function studies. The correlation coefficient between the 2 measurements was 0.97. In addition to its use as an index of differential effective renal plasma flow 99mtechnetium penicillamine is an excellent cortical imaging agent and the relative distribution of 99mtechnetium penicillamine between the 2 kidneys and within a single kidney can be assessed qualitatively by visual inspection of the scan.