Dual-energy computed tomography in reducing the effective radiation dose of computed tomography urography in patients with urinary calculi

BACKGROUND: To evaluate the diagnostic performance of split-bolus single-phase dual-energy computed tomography (DECT) with virtual non-contrast computed tomography (VNCT) compared to three-phase computed tomography (CT) urography in patients with urinary calculi, and to examine the performance of split-bolus single-phase DECT when reducing the effective dose. METHODS: A total of 48 patients with abdominal pain or hematuria suggestive of unilateral urinary calculi were enrolled and randomly divided into the experimental and control groups, with 24 cases in each group. Patients in the experimental group underwent split-bolus single-phase DECT to obtain a mixed nephrographic excretory phase. Patients in the control group accepted a single-bolus three-phase CT urography scan (non-contrast, nephrographic phase, and excretory phase). The CT values and the contrast-to-noise ratio (CNR) of 7 segments of the urinary tract were measured and compared between the two groups by using the Mann–Whitney U test. The dose-length product (DLP) and effective dose of each patient were compared between the two groups using an independent t-test. RESULTS: Among all 48 patients, 35 calculi were detected in the experimental group (n=24), and 47 calculi were detected in the control group (n=24). There was no significant difference between the two groups in both CT value measurements and the CNR. The mean DLP and mean effective dose of the experimental group were significantly lower than those of the control group, and the effective dose in the experimental group was decreased by 40% compared with the control group. CONCLUSIONS: The application of DECT combined with split-bolus nephrographic excretory phase CT urography can reveal the urinary calculi covered by a contrast medium and also reduce the effective dose exposure to patients.