Helical CT and ureteral colic.

The advantages of nonenhanced helical CT for the diagnosis of ureteral calculi include rapid scan time and patient throughput, safety (no contrast, less radiation), cost-effectiveness, high accuracy, minimal invasiveness, and ability to suggest of alternative diagnoses for flank pain--urologic and otherwise. Size measurement and location in the ureter, the two most important determinants of therapy, are precise with CT. It is particularly good for imaging small or radiolucent calculi, and calculi located at the ureterovesical. Secondary signs of obstruction and the soft-tissue rim sign are additional aids to the routine diagnosis of ureteral calculi. CT numbers indicate the fragility and therefore the likelihood of successful treatment of a calculus. Postprocessing options may help guide management decisions and may help plan interventions. The authors' experience after 30 months of using helical CT exclusively in the work-up of ureteral colic has been extremely favorable. Without hesitation, the authors believe that nonenhanced helical CT is the study of choice for the work-up of ureteral calculi.