Relationship between cone-beam CT technique and diagnostic usefulness in patients undergoing embolotherapy for hepatocellular carcinoma

Abstract

To determine the effect of different numbers of projection images in C-arm cone-beam computed tomography (CBCT) on diagnostic content and image quality in patients undergoing angiographic embolotherapy for hepatocellular carcinoma (HCC). A total of 29 patients who underwent contrast-enhanced conventional multidetector CT (MDCT) within 6 weeks prior to CBCT acquired during embolotherapy for HCC between 2010 and 2013 were included in the study. CBCT was acquired in each patient using a 5-s (248 projection images) or 8-s (396 projection images) protocol. Anonymised images were reviewed independently by an interventional radiologist blinded to CBCT group. MDCT was used as a reference to the patient's anatomy, and performance of CBCT was compared to that of MDCT in each group. The level of concordance between CBCT and MDCT within each group was assessed for the following variables: number of foci >1 cm, largest tumour diameter, highest order branching vessel identified, image quality, diagnostic quality, signal-to-noise ratio, and contrast-to-noise ratio (CNR). CBCT radiation dose was recorded. There was no significant difference between MDCT and CBCT within each group in the number of tumour foci >1 cm identified or size of the largest focus measured. MDCT had superior image quality compared to both CBCT groups (p<0.01), but CBCT demonstrated subsegmental branches more often in each group than MDCT. Both CBCT groups demonstrated higher CNR than MDCT (p<0.01). The dose-area product (3675±1295 versus 6598±1252 μGy·m2; p<0.001) and skin dose (119±41 versus 212±38 mGy; p<0.001) were significantly lower with 5-s CBCT than with 8-s CBCT. The relationship between MDCT and CBCT in both groups was consistent. The information obtained with 5-s CBCT was equivalent to that obtained with 8-s CBCT but with a lower radiation dose.