Diuresis renal scintigraphy "F-0" in diagnosing of upper urinary tract obstruction in children: the clinical significance

Abstract

Background: The aim of this study was to assess the clinical relevance of diuresis renal scintigraphy after simultaneously administered radiopharmaceutical and diuretic (DRS "F-0") in diagnosing obstruction of upper urinary tract in children with previously documented hydronephrosis and ureterohydronephrosis, analyzing the value of qualitative and quantitative scintigraphy parameters.

Material and methods: This retrospective study enrolled 82 children (30 girls and 52 boys aged between 2 months and 16 years; mean 5.8 +/- 4.5 years) with previously documented hydronephrosis or ureterohydronephrosis (42 left-sided, 28 right-sided and 12 bilateral). DRS "F-0" was started after intravenous administration of diethylene-triamine- pentaacetic acid (DTPA) mixed with furosemide. Results of DRS "F-0" were analyzed qualitatively (visual analysis of scintigrams and renography curves) and quantitatively (time to reach maximum of the kidney curve-T max, washout of the tracer-WO, the furosemide clearance half-time (F/2) and individual kidney function - IKF) and compared with the final diagnoses obtained in 37 children (42 nephroureteric units - NU) after surgery, in 41 children (48 NU) during the medical follow-up lasting at least 6 months, and in 4 children (4 NU) using invasive diagnostic procedures. Diagnostic criteria for obstructed NU (kidney with corresponding ureter) considered presence of pathological at least two of five scintigraphy variables characterized as a sign of obstruction.

Results: Forty true positive and 37 true negative results were detected using diagnostic criteria for obstructed and normal NU by means of DRS "F-0". DRS "F-0" failed to detect obstruction in 5 children with a total of 6 obstructed NU, while the results were marked as false positive in 9 children (11 NU). Qualitative scintigraphy analysis was found to be the most sensitive (91%) and accurate predictor (85%) in differentiating obstruction from non-obstructive renal unit. High sensitivity in predicting obstruction was also found for both washout of the radiopharmaceutical (87%) and for furosemide clearance half time (85%). Overall sensitivity of DRS "F-0" using proposed diagnostic criteria in differentiating obstruction was 87%, specificity 77% and accuracy 82%. However, DRS "F-0" has been shown to be more sensitive (90%) in children with UPJ and UVJ obstruction concerning children in whom obstruction was caused by other urinary tract diseases.

Conclusion: This study showed DRS "F-0" as a sensitive and reliable method in diagnosing children with obstructions of the upper urinary tract. The great advantage of the protocol DRS "F-0" over other diuresis renography protocol modalities is due to the shorter time of the acquisition by half, and the avoidance of additional diuretic application. However, conventional quantitation of diuresis renogram did not improve the sensitivity and specificity with respect to the qualitative analysis of scintigrams and renography curves.