Relative accuracy of renal scan in estimation of renal function during partial ureteral obstruction

This study is designed to evaluate the relative ability of DMSA and DTPA renal scans to accurately reflect differential renal function (DRF) compared with inulin clearance in the presence of partial unilateral ureteral obstruction. DRF was determined in 29 young rabbits by both renal scans. In the experimental group (n=21), left partial ureteral obstruction was created. Following 8 to 24 weeks, individual renal function in the obstructed animals were assessed by both renal scans and clearance of inulin. Eight animals were used as control. In the control group, DRF measured by DMSA, but not DTPA, correlated well with inulin clearance. Both scans documented a significant change in the DRF of the obstructed group (p<0.001). In the partially obstructed kidneys DRF derived by inulin was significantly lower than that measured by DMSA or DTPA scans (p<0.001 and p<0.0001). DRF measured by DMSA correlates well with inulin clearance in the control group. A similar correlation was not obtained by DMSA in the presence of obstruction. DTPA does not correlate with inulin clearance either in the control or the obstructed group.