To investigate the application value of renal depth correction by the integrated CT in glomerular filtration rate (GFR) determination by ⁹⁹Tc^m-diethylene triamine pentoacetic acid (DTPA) renal dynamic imaging for patients with hydronephrosis.

A total of 338 patients (191 males, 147 females, age (49.6±14.5) years) in Beijing Tsinghua Changgung Hospital from April 2016 to June 2019 with different degrees of hydronephrosis were respectively analyzed. Patients were divided into groups of normal-mild, normal-moderate, normal-heavy, mild-mild, mild-moderate, mild-heavy, moderate-moderate, moderate-heavy and heavy-heavy according to the degree of bilateral hydronephrosis. The renal depth was measured by the integrated CT method and the routine method, and the absolute value of bilateral renal depth difference in normal-mild, normal-moderate and normal-heavy groups was calculated by the 2 methods. Based on the renal depth measured by the 2 methods, the single renal GFR was measured by ⁹⁹Tc^m-DTPA dynamic renal imaging Gates method and compared between the 2 methods. Total GFR measured by the 2 methods were compared with estimated GFR (eGFR). One-way analysis of variance analysis, paired t test, and Pearson correlation analysis were used.

For the integrated CT measurements, the absolute value of bilateral renal depth difference in normal-mild, normal-moderate and normal-heavy groups were significantly different ((0.39±0.24), (1.16±0.65) and (1.00±0.90) cm; F=15.241, P<0.05). The renal depth and the single renal GFR measured by the integrated CT method were higher than those measured by the routine method (t values: 16.06-19.78, 14.27-17.23, all P<0.05) in the kidneys with normal, mild, moderate and heavy hydronephrosis. There were significant differences between the total GFR measured by the routine method and eGFR in all groups (t values: from -8.178 to 5.879, all P<0.05); however, in the integrated CT method, except that the total GFRs in moderate-heavy group and heavy-heavy group were overestimated (t values: 3.035 and 11.247, both P<0.05), there were no significant differences between the total GFR ((111.57±17.37), (103.71±15.22), (79.79±12.62), (100.33±18.49), (100.28±15.43), (84.09±20.72) and (74.14±14.57) ml·min^-1·1.73 m^-2) and eGFR ((109.16±12.81), (103.20±13.26), (78.60±14.12), (100.98±15.20), (99.89±14.05), (84.61±20.24) and (73.44±14.57) ml·min^-1·1.73 m^-2) in normal-mild, normal-moderate, normal-heavy, mild-mild, mild-moderate, mild-heavy and moderate-moderate groups (t values: from -0.301 to 1.948, all P>0.05). The total GFR measured by the 2 methods were significantly correlated with eGFR in 338 patients with hydronephrosis (r values: 0.888 and 0.928, both P<0.01).

Compared with the routine method, except for the moderate-heavy group and heavy-heavy group, renal depth correction by the integrated CT may have greater clinical significance in GFR measurement by renal dynamic imaging for patients with hydronephrosis.

Hydronephrosis; Radionuclide imaging; Technetium Tc 99m pentetate; Glomerular filtration rate; Tomography, X-ray computed