Radiology. 2015 May 20:142821. [Epub ahead of print]
Schernthaner RE1, Chapiro J1, Sahu S1, Withagen P1, Duran R1, Sohn JH1, Radaelli A1, van der Bom IM1, Geschwind JH1, Lin M1.
Purpose
To compare liver coverage and tumor detectability by using preprocedural magnetic resonance (MR) images as a reference, as well as radiation exposure of cone-beam computed tomography (CT) with different rotational trajectories.
Materials and Methods
Fifteen patients (nine men and six women; mean age ± standard deviation, 65 years ± 5) with primary or secondary liver cancer were retrospectively included in this institutional review board-approved study. A modified cone-beam CT protocol was used in which the C-arm rotates from +55° to -185° (open arc cone-beam CT) instead of -120° to +120° (closed arc cone-beam CT). Each patient underwent two sessions of transarterial chemoembolization between February 2013 and March 2014 with closed arc and open arc cone-beam CT (during the first and second transarterial chemoembolization sessions, respectively, as part of the institutional transarterial chemoembolization protocol). For each cone-beam CT examination, liver volume and tumor detectability were assessed by using MR images as the reference. Radiation exposure was compared by means of a phantom study. For statistical analysis, paired t tests and a Wilcoxon signed rank test were performed.
Results
Mean liver volume imaged was 1695 cm3 ± 542 and 1857 cm3 ± 571 at closed arc and open arc cone-beam CT, respectively. The coverage of open arc cone-beam CT was significantly higher compared with closed arc cone-beam CT (97% vs 86% of the MR imaging liver volume, P = .002). In eight patients (53%), tumors were partially or completely outside the closed arc cone-beam CT field of view. All tumors were within the open arc cone-beam CT field of view. The open arc cone-beam CT radiation exposure by means of weighted CT index was slightly lower compared with that of closed arc cone-beam CT (-5.1%).
Conclusion
Open arc cone-beam CT allowed for a significantly improved intraprocedural depiction of peripheral hepatic tumors while achieving a slight radiation exposure reduction. © RSNA, 2015 Online supplemental material is available for this article.