Usefulness of Corticomedullary-Phase CT Urography in Patients with Suspected Acute Renal Colic Visiting the Emergency Department

PURPOSE: To evaluate the sensitivity of corticomedullary-phase imaging for detecting urinary stones in patients with renal colic who visited the emergency department. MATERIALS AND METHODS: This retrospective study included 253 patients with suspected renal colic from two tertiary hospitals in South Korea, who visited the emergency department and underwent CT urography. Two radiologists blinded to the clinical history independently reviewed the corticomedullary-phase images. The sensitivity for identifying urinary stones were evaluated for each reviewer. After the initial evaluation, the images were re-evaluated based on patient history. The sensitivity of re-evaluation were recorded. RESULTS: Of 253 patients, 150 (59%) had urinary stones. Among them, significant stones were observed in 138 patients (92%), and obstructive changes on CT in 124 patients (82.7%). For identifying significant urinary stones, the sensitivity was 98.6% (136/138) for both the reviewers. For identifying significant urinary stones with urinary obstruction, the sensitivity was 99.2% (123/124) for reviewer 1, and 100% (124/124) for reviewer 2. The sensitivity for identifying significant stones increased from 98.6% to 100% for reviewer 1, and from 98.6% to 99.3% for reviewer 2 in the re-evaluation session. CONCLUSION: The corticomedullary-phase CT urography was sensitive for diagnosing urolithiasis in patients with acute renal colic who visited the emergency department.