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Comparison Between Ultrasound and Dimercaptosuccinic Acid Scintigraphy In the Evaluation of Renal Scars

Sunday, October 21, 2012: 1:40 PM
Grand Ballroom B (Hilton Riverside)
Maryse Marceau-Grimard1, Christian Côté2, Stéphane Bolduc1, Marcel Dumont2 and Katherine Moore1, (1)Urology, CHUL-CHUQ, Université Laval, Quebec City, QC, Canada, (2)Nuclear medicine, CHUQ, Université Laval, Québec, QC, Canada

Purpose: Dimercaptosuccinic acid (DMSA) scintigraphy is the gold standard in the evaluation of renal scars and is widely used for this purpose in the pediatric population even if it necessitates radiation exposure. A few studies have compared, with opposite results, the sensitivity and specificity of renal ultrasound to DMSA scans in the detection of renal scars, to simplify the clinical management of patients. With more sensitive ultrasound equipment purchased in our tertiary pediatric center, our objective is to evaluate if renal ultrasounds performed in our practice could be sufficient and equivalent to the information provided by DMSA scintigraphy regarding renal scars.

Methods: The radiological charts of all 284 patients that had undergone a DMSA scintigraphy between January 2009 and February 2012 have been reviewed. Correlation between ultrasound and DMSA scans results for the search of renal scars was the main focus. Two hundred fifty (250) patients and 467 renal units have been included after exclusion of patients with difference higher than a year between the ultrasound and nuclear studies or anatomical features that invalidate one of the studies.

Results: Of the 467 renal units evaluated, 46 (9,9%) presented scarring on ultrasound examination and 118 (25,3%) on DMSA scintigraphy (ultrasound sensibility (se) 29,7%, specificity (sp) 96,9%). Thirty-five (35) of the 46 (76%) kidneys with a scar on ultrasound examination had scarring confirmed on the nuclear exam. The results are similar when we compare ultrasound evaluations performed with newer to older machines (older: se 31,6%, sp 96.8%; newer : se 21,7%, sp 97%). When considering only the ultrasound and DMSA scans evaluations done in the same week, the results remain in the same range. Globally, if result are analyzed by patient for more clinical significance, of the 250 patients, 41 (16%) demonstrated scarring on ultrasound compared to 99 (39,6%) on scintigraphy.

Conclusion: In our center, the actual use of the ultrasound data is not powerful enough to give reliable information about renal scarring, even with more sensitive instruments. Even with its inconvenient, DMSA scintigraphy is still mandatory in the evaluation of renal scars to help in our clinical decision making.