The unrivalled advantage of CT over all other techniques is its diagnostic accuracy. Over 99% of stones, including those that are radiolucent on plain radiographs, will be seen on NCHCT.
The exceptions are pure matrix stones and stones made of indinavir sulphate, an HIV protease inhibitor and similar medication. NCHCT has the highest diagnostic accuracy (approximately 95% compared to around 80% for IVU) for acute ureteric colic. NCHCT can provide almost all information required for management of a patient with a ureteric calculus, although it is often supplemented by KUB for follow-up purposes. As well as demonstrating the size and location of the calculus, measurement of stone density may be useful, as stones of greater than 1000HU appear to respond less well to ESWL.