Identification of intra-hepatic communicating veins through the arch sign on CT-scan

Knowledge of vascular outflow is essential in liver surgery. Communicating veins between the right hepatic vein (RHV) and the middle hepatic vein (MHV) have been described and allowed us to perform new surgical procedures. The aim of this study was to predict the existence of intra-hepatic venous anastomosis by identifying communicating veins on 2D CT-scan imaging. We retrospectively analysed data from 32 patients operated on for liver tumours between 2004 and 2013 who underwent a bisegmentectomy VI-VII enlarged to the RHV and/or a bisegmentectomy VII-VIII and/or a left hepatectomy enlarged to the MHV and who had pre and post-operative CT-scans. Patients with cirrhosis were excluded. We first analysed post-operative images and, in patients with a proven collateral vein, looked for evidence of this on pre-operative imaging. We then validated this pre-operative sign against post-operative imaging. Collaterals from both the RHV and the MHV formed an arch visible on pre-operative imaging which predicted the development of intrahepatic venous anastomosis in 20 patients. In 14 patients, a perfect match between the arch sign and development of collaterals was observed (n = 28). Sensitivity, specificity, negative and positive predictive values were 87, 80, 80, and 87%, respectively. Positive and negative likelihood ratio tests were 4.3 and 0.16, respectively. Communicating veins between the RHV and the MHV are frequent and can be predicted by the arch sign on 2D CT-scan. Hence the arch sign can be very useful when planning liver surgery.