Three-dimensional evaluation of lipiodol retention in HCC after chemoembolization: a quantitative comparison between CBCT and MDCT

Abstract

Rationale and objectives: To evaluate the capability of cone-beam computed tomography (CBCT) acquired immediately after transcatheter arterial chemoembolization (TACE) in determining lipiodol retention quantitatively and volumetrically when compared to 1-day postprocedure unenhanced multidetector computed tomography (MDCT).

Materials and methods: From June to December 2012, 15 patients met the inclusion criteria of unresectable hepatocellular carcinoma (HCC) that was treated with conventional TACE (cTACE) and had intraprocedural CBCT and 1-day post-TACE MDCT. Four patients were excluded because the lipiodol was diffuse throughout the entire liver or lipiodol deposition was not clear on both CBCT and MDCT. Eleven patients with a total of 31 target lesions were included in the analysis. A quantitative three-dimensional software was used to assess complete, localized, and diffuse lipiodol deposition. Tumor volume, lipiodol volume in the tumor, percent lipiodol retention, and lipiodol enhancement in Hounsfield units (HU) were calculated and compared between CBCT and MDCT using two-tailed Student's t test and Bland-Altman plots.

Results: The mean value of tumor volume, lipiodol-deposited regions, calculated average percent lipiodol retention, and HU value of CBCT were not significantly different from those of MDCT (tumor volume: 9.37 ± 11.35 cm(3) vs 9.34 ± 11.44 cm(3), P = .991; lipiodol volume: 7.84 ± 9.34 cm(3) vs 7.84 ± 9.60 cm(3), P = .998; lipiodol retention: 89.3% ± 14.7% vs. 90.2% ± 14.9%, P = .811; HU value: 307.7 ± 160.1 HU vs. 257.2 ± 120.0 HU, P = .139). Bland-Altman plots showed only minimal difference and high agreement when comparing CBCT to MDCT.

Conclusions: CBCT has a similar capability, intraprocedurally, to assess lipiodol deposition in three dimensions for patients with HCC treated with cTACE when compared to MDCT.

Keywords: Hepatocellular carcinoma; cone-beam computed tomography; multidetector computed tomography; three-dimensional; transcatheter arterial chemoembolization; volumetric.

Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

3D volumetric semi-automatic evaluation of complete lipiodol retention in HCC on a representative case. Segmentation of the tumor (red circle) on CBCT at corresponding slice level as MDCT (A, B). 3D segmentation volume rendering on the same slice (C, D). Quantitative lipiodol color map of CBCT and MDCT (E, F). The box represents the location of the background ROI. The tumor volume on CBCT and on MDCT was 4.69cm3 and 3.97 cm3, respectively. The volume of lipiodol on CBCT and on MDCT was 4.66cm3 and 3.97cm3, respectively.

Figure 2

3D volumetric semi-automatic evaluation of diffuse lipiodol retention in HCC on a representative case. Segmentation of the tumor (red circle) on CBCT at corresponding slice level as MDCT (A, B). 3D segmentation volume rendering on the same slice (C, D). Quantitative lipiodol color map of CBCT and MDCT (E, F). The box represents the location of the background ROI. The tumor volume on CBCT and on MDCT was 50.89cm3 and 50.78 cm3, respectively. The volume of lipiodol on CBCT and on MDCT was 42.87cm3 and 45.30 cm3, respectively.

Figure 3

Bland-Altman plots comparing tumor volume, lipiodol retention between CBCT and MDCT. These plots graphically show the agreement between the two measurement methods. The heavy line is the mean difference and the dashed line is ±2 standard deviations. As shown by the plots, different modalities show excellent agreement, and the low variability.