Does liver resection/transplantation affect respiratory induced liver motion in patients with hepatocellular carcinoma?

The purpose of this study was to evaluate the changes in magnitude of three-dimensional (3D) liver motion after liver resection/transplantation in patients with hepatocellular carcinoma (HCC) using four-dimensional (4D)-computed tomography (CT) images. From January 2012 to April 2016, 74 HCC patients underwent 4D-CT scans under a free-breathing state to assess respiratory liver motion. Of the 74 patients, 40 did not have a liver resection/transplantation (Group A), 34 with liver resection/transplantation. 15 underwent major or minor resection in the right liver lobe (Group B), 14 underwent major or minor resection in the left liver lobe (Group C), and five underwent liver transplantation (Group D). The 4D-CT images were sorted into 10 image series according to the respiratory phase from the end inspiration to the end expiration, and then transferred to treatment planning software. All liver contours were drawn by a single physician and confirmed by a second. Liver relative coordinates were automatically generated to calculate liver respiratory motion in different axial directions and compiled into a single composite image. Differences in respiratory liver motion were assessed using one-way ANOVA. The average liver respiratory motion in the cranial-caudal direction and 3D magnitude were 10.46 ± 2.78 mm (range, 5.60-18.80 mm) and 11.74 ± 2.65 mm (range, 7.45-20.79 mm) for patients without liver resection/transplantation, and 7.74 ± 2.79 mm (range, 2.20-12.90 mm) and 9.07 ± 2.38 mm (range, 4.79-14.08 mm) for posthepatectomy/post-transplant patients respectively. There were significant differences between Group A and B, Group A and C, Group A and D. However, there were no significant differences among Group B, C, and D. Liver resection/transplantation greatly affected respiratory-induced liver motion in patients with HCC. We, therefore, recommend discriminatory internal target volume (ITV) determination for patients with or without liver resection/transplantation undergoing external radiotherapy for hepatic tumors while respiratory motion management is unavailable.