Detection and characterization of focal liver lesions by split-bolus multidetector-row CT: diagnostic accuracy and radiation dose in oncologic patients

Abstract

Aim: To assess the diagnostic accuracy and radiation dose of split-bolus multidetector-row computed tomography (MDCT) protocol in the detection and characterization of focal liver lesions in oncologic patients.

Patients and methods: We retrospectively analyzed triphasic CT at initial diagnosis and follow-up split-bolus 64-detector row CT protocol in 48 oncologic patients with focal liver lesions. Split-bolus MDCT protocol by i.v. injection of two boli of contrast medium combines hepatic arterial phase (HAP) and hepatic enhancement during portal venous phase (PVP) in a single pass. First bolus: 75-90 mL at 2.0 mL/sec to obtain adequate hepatic enhancement during the PVP; second bolus: 60 mL/sec at 3.5 mL/sec to ensure HAP. Each bolus is followed by 20 mL of saline solution at the same flow rate. Sensitivity, specificity, positive predictive value and negative predictive value of split-bolus MDCT protocol were calculated for detection and characterization of liver lesions. The effective radiation dose (ED) was calculated using dose-length product (DLP) values in mSv determined using a conversion factor.

Results: compared to triphasic-MDCT, split-bolus MDCT protocol confirmed all the 210 lesions identified and characterized by triphasic-MDCT technique, unchanged during the follow-up. The mean ED was 27.8 ± 6 mSv for chest-abdomen-pelvis biphasic split-bolus MDCT and 45.7 ± 13.6 mSv for triphasic-MDCT.

Conclusion: The diagnostic efficacy of split-bolus protocol is comparable to that of triphasic protocol at MDCT with a reduction in radiation dose of approximately 35-40%.

Keywords: Helical Computed Tomography (CT); Liver; Multidetector row CT (MDCT); neoplasm; oncology; split-bolus technique; triphasic technique.