To explore the value of ⁹⁹Tc^m-diethylene triamine pentaacetic acid (DTPA) renal dynamic imaging combined with double plasma glomerular filtration rate (GFR) in the evaluation of split renal function in adult patients undergoing interventional therapy for unilateral hydronephrosis.

Retrospective analysis of 79 patients (39 males, 40 females, age (41.4±16.3) years) with unilateral hydronephrosis in First Hospital of Shanxi Medical University from January 2015 to December 2019 were performed. All patients underwent surgery to relive obstruction. ⁹⁹Tc^m-DTPA renal dynamic imaging was performed before and after surgery to obtain bilateral renogram and GFR was measured by Gates method (marked as gGFR). Meanwhile, the corrected double plasma method was used to measure the GFR of both kidneys (marked as dGFR_all). Double plasma GFR of the affected kidney (marked as dGFR) was obtained according to the ratio of renogram and dGFR_all. Patients were divided into mild to moderate group (dGFR≥20 and <40 ml·min^-1·1.73 m^-2 ), severe group (dGFR≥10 and <20 ml·min^-1·1.73 m^-2) and extremely severe group (dGFR<10 ml·min^-1·1.73 m^-2) according to dGFR before surgery. Postoperative renal dynamic imaging and dGFR were reexamined to analyze the GFR recovery values (ΔgGFR, ΔdGFR). Data were analyzed by χ² test, paired t test, one-way analysis of variance, Pearson correlation analysis and Bland-Altman consistency test.

There were 34 patients in mild to moderate group, 24 patients in severe group, 21 patients in extremely severe group. Significant differences were found in both gGFR and dGFR before and after surgery in mild to moderate group, as well as those in the extremely severe group (t values: 2.42-3.34, all P<0.05 ), but there was no significant difference in severe group (t values: 1.24, 1.27, both P>0.05). The ΔgGFR and ΔdGFR were not significantly different among three groups (F values: 0.45, 0.34, both P>0.05). GFR mesured by the 2 methods (gGFR, dGFR) before and after operation correlated well in each group (before surgery, r values: 0.68-0.82; after surgery, r values: 0.80-0.91, all P<0.001). GFR measured by the two methods showed poor consistency in the mild to moderate and severe groups (>5%(5.88%, 2/34; 8.33%, 2/24) values before and after surgery exceeding 95% consistency limit), while good consistency was demonstrated in the extremely severe group (<5%(4.76%, 1/21) values before and after surgery exceeding 95% consistency limit).

Preoperative GFR in patients with unilateral hydronephrosis cannot predict the recovery of renal function after interventional treatment. For the evaluation of split renal GFR in patients with unilateral upper urinary tract obstructive hydronephrosis, corrected dual plasma method combined with kidney ratio of renogram is more appropriate for the determination of GFR. Gates method has some limitations, however, it can be recommended for the evaluation of GFR in patients with extremely severe renal impairment before and after interventional surgery.

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