A Comparative Study of Normalized Residual Activity and Standard Parameters in 99mTc-DTPA Diuretic Renography:

The present study aims to compare the diagnostic performance of Normalized Residual Activity (NORA) with conventional renographic parameters obtained from 99mTc-diethylenetriamine pentaacetic acid (99mTc-DTPA) diuretic renography in the evaluation of patients with suspected urinary tract obstruction. The study seeks to determine whether NORA provides superior diagnostic accuracy and specificity for differentiating true urinary tract obstruction from non-obstructive dilatation, thereby improving the interpretation of diuretic renography and supporting appropriate clinical decision-making.

Inclusion Criteria: Patients fulfilling all of the following criteria will be eligible for inclusion: 1. Pediatric or adult patients referred for 99mTc-DTPA diuretic renography because of suspected urinary tract obstruction. 2. Availability of a clinical reference standard (e.g., confirmation of obstruction via surgical findings/pyeloplasty, or proven non-obstruction via stable long-term clinical and radiological follow-up of at least 6-12 months). Exclusion Criteria: Patients meeting any of the following criteria will be excluded: 1. Patients with severe renal impairment. 2. Patients with renal congenital anomalies e.g. horseshoe kidneys 3. Technical failure during the scan, including severe patient motion artifacts or failure to properly administer the diuretic