Clinical Evaluation of Ultra-Low Dose Contrast-Enhanced CT in Patients Presenting with Acute Ureteric Colic

Abstract

Objective: To determine the diagnostic accuracy of ultra-low dose contrast-enhanced CT (ULDCECT) and its ability to measure differential renal function (DRF) in patients presenting clinically with acute ureteric colic by comparison to IVU (using an equivalent radiation exposure) and DMSA, respectively. Patients and methods: Fifty-three patients presenting clinically with acute ureteric colic underwent IVU, ULDCECT and DMSA on the same day of their hospital admission. Diagnostic accuracy of ULDCECT and IVU was compared to interventional findings and clinical outcome. Estimation of DRF by ULDCECT was derived through measurement of enhancing renal volumes and DMSA. Results: ULDCECT had superior sensitivity (97%) and specificity (100%) in the identification of renal tract stone disease compared to IVU (84 and 95% respectively), with comparable radiation exposure (1.7 mSv versus 1.4 mSv). Furthermore, ULDCECT revealed non-urological pathology in eight patients (15%), including perforated abdominal viscus and acute appendicitis. There was a very good correlation of ULDCECT and DMSA-derived DRF (regression of near unity, Pearson's correlation coefficient of 0.72 ( p < 0.0001)). Conclusion: ULDCECT provides diagnostically accurate imaging in patients presenting with acute ureteric colic and significantly outperforms IVU for a comparable radiation burden. Use of ULDCECT instead of conventional CT-KUB may significantly reduce lifetime radiation exposure of ureteric colic patients without loss of diagnostic accuracy.