Room: Exhibit Hall | Forum 8
Purpose: To study the feasibility of defining the individual internal gross tumor volume (IGTV) of hepatocellular carcinoma (HCC) using four-dimensional computed tomography (4DCT) imaging and T2-weighted Magnetic Resonance Imaging (MRI-T2) by deformable registration.
Methods: Ten HCC patients who previously received radiotherapy treatment were selected for this study. The following simulation images were acquired sequentially: 4DCT in free breathing and MRI-T2 in deep-inspiration breath holding. All 4DCT images were sorted into ten phases according to breath cycle (CT00â€“CT90). The accuracy of DR was assessed by three methods; the maximum displacement on three dimensional directions of portal vein, the maximum displacement on three dimensional directions of the celiac trunk, and the ratio of liver overlap (P-LIVER). Gross tumor volumes (GTVs) were contoured on all CT images and the IGTV obtained by merging the GTVs in each phase of 4DCT imaging. The GTV on the MRI-T2 image was deformably registered to each 4DCT phase image using MIM software version 6.5.6 and the results labeled as â€“DR. The IGTVDR was obtained by merging the GTVDR on the 4DCT images. Statistical differences in the GTVs and between the IGTV and IGTVDR were assessed by a paired t-test.
Results: The P-LIVER was 115.4Â±13.8%. Then the Reg Reveal and Reg Refine were used to minmize the registration error manually. The edge of most lesions could be definitively identified using MRI-T2 images compared to 4DCT images. The GTVs after DR on 4DCT different phase imaging increased by an average of 8.18ï¼… (Pï¼œ0.05), whilst the volume of IGTVDR increased by an average of 9.67% compared to that of IGTV (Pï¼œ0.05).
Conclusion: The use of 4DCT imaging alone has the potential risk of missing a partial volume of the HCC. However, MRI-T2 images can carry more information than 4DCT image. As such, the combination of 4DCT and MRI-T2 images using the DR technique may improve accuracy in the delineation of HCC.
Not Applicable / None Entered.