Comparison between ultrasound and noncontrast helical computed tomography for identification of acute ureterolithiasis in a teaching hospital setting

Abstract

Context and objective: Recent studies have shown noncontrast computed tomography (NCT) to be more effective from ultrasound. [US] for imaging acute uroferolithlasis. However, to our knowledge, there are few studies directly comparing these techniques in an emergency teaching hospital setting. The objectives of this study were to compare the diagnostic accuracy of US and NCT performed by senior radiology residents for diagnosing acute ureterolithtasis; and to assess interobserver agreement on tomography interpretations by residents and experienced abdominal radiologists. Design and Setting: Prospective study of 52 consecutive potients, who underwent both US and NCT within an Interval of eight hours; at Hospital São Paulo. Methods: US scans were performed by senior residents and read by experienced radiologists. NCT scan images were read by senior residents; and subsequently by three abdominal radiologists, The interobserver variability was assessed using the kappa statistic. Results: Ureteral colculi were found in 40 out of 52 patients (77%). US presented sensitivity of 22% and specificity of 100%. When collecting system dilatation was associated, US demonstrated 73% sensitivity, 82% specificity The interobserver agreement in NCT analysis was very high with regard to Idenification of calculi, collecting system dilatation and stranding of perinephric fat. Conclusions: US has limited value for Identifying ureteral calculi in comparison with NCT, even when collecting system dilatation is presents. Resident and abdominal radiologists demonstrated excellent agreement rates for ureteral calculf, identification of collecting system dilatation and stranding of perinephric far on NCT. Copyright © 2007, Associação Paulista de Medicina.