Aim:
This study evaluates the diagnostic accuracy of serial ultrasonography (dynamic ultrasonography, DUSG) when performed concurrently with dynamic renal scintigraphy (DRS) in detecting obstructive hydronephrosis (HN) in children undergoing DRS for suspected urinary obstruction.
Patients and Method:
Thirty-five patients with unilateral HN requiring DRS between June 2022 and August 2024 were included. Standardized DUSG measurements were obtained at predefined time points: 30 minutes before DRS (USG1), at DRS initiation (USG2), at DRS completion (USG3), and one hour after furosemide administration (USG4). Prospective data from both modalities were analyzed and compared.
Results:
DRS showed radiotracer clearance half-life (t½) <10 minutes in 19 patients, 10–20 minutes in 6 patients, and >20 minutes with no response in 10 patients.
DUSG revealed persistent HN in 17 patients at USG4, while APD returned to baseline or decreased further in 18 patients. Although DRS and DUSG demonstrated consistent graphical patterns, their timing varied. The regression of t½ and APD occurred at different time points.
When comparing APD values between USG3 and USG4, the average reduction rate (emptying percentage) was found to be 20%. In the non-responsive group, the emptying percentage was 4.63%, indicating a significant difference compared to the remaining patients.
Conclusion:
Integrating DRS and DUSG improves diagnostic accuracy for ureteropelvic junction obstruction. While nuclear clearance and anatomical regression are correlated, they occur at different time points. The APD emptying percentage on DUSG serves as a predictor of obstruction on DRS. Further large-scale, multicenter studies are needed to validate these findings.
Keywords: hydronephrosis, dynamic ultrasonography, dynamic renal scintigraphy, urinary obstruction
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