Table 2. Comparison between ultrasound and noncontrast helical computed tomography for identifying ureteral stone and/or intrarenal collecting system dilatation.

	NCT positive for ureteral stone and/or intrarenal collecting system dilatation	NCT negative for ureteral stone and/or intrarenal collecting system dilatation	Total
US positive for ureteral stone and/or intrarenal collecting system dilatation	30	2	32
US negative for ureteral stone and/or intrarenal collecting system dilatation	11	9	20
Total	41	11	52

NCT = noncontrast helical computed tomography; US = ultrasound; k = 0.42 (42%) for agreement between senior residents and experienced radiologists.