**2. Materials and methods**

A total of 759 patients without liver disease were enrolled in this study from July 2013 to November 2017. Upper abdominal contrast-enhanced computed tomography (CT) image data were collected for all patients. Patient selection criteria were as follows: (1) no liver lesions or other diseases affecting the portal vein arrangement; (2) availability of high-quality CT imaging that clearly displayed the portal vein up to its fourth-level branch; (3) no history of liver surgery; and (4) CT layer thickness less than 1 mm. This study was approved by the research ethics committee of the affiliated hospital of Qingdao University, and written informed consent was obtained from all parents.

All included patients underwent upper abdomen contrast-enhanced CT (Discovery HD 750; GE Healthcare, Milwaukee, WI, USA and Definition Flash; Siemens Healthcare, Forchheim, Germany). The scan parameters were set as follows: nonionic contrast agent (Iopromide 350 mg I/mL; Schering Ultravist, Berlin, Germany) was injected via the forearm elbow vein or the hand vein with a doubletube high-pressure syringe (Stellant; Medrad, Indianola, PA, USA). Approximately 1.5–2.0 mL/kg body weight of contrast was injected at a rate of 1.0–3.0 mL/s. For Definition Flash CT, the tube rotation time was 0.28 s, detector collimation was 2\*64\*0.6 mm, and pitch was 1.0. For Discovery HD 750 CT, the tube rotation time was 0.5 s, detector collimation was 64\*0.625 mm, pitch was 0.984, and noise index was 10.

### **2.1. Image processing and 3D reconstruction based on artificial intelligence**

DICOM data of the upper abdomen CT were uploaded into the Hisense Computer Aided Surgery System (Hisense CAS, version 2.1.3; Qingdao, China) for 3D reconstruction [3–5]. The following steps were performed: liver image extraction (liver segmentation was performed automatically through the artificial intelligence automatic adjustment of the window width and window level); extraction of intrahepatic vascular system (the scope of blood vessel formation was determined through the

*A New Liver Segmentation Based on Digital Liver Portal Vein Ramification Using… DOI: http://dx.doi.org/10.5772/intechopen.111542*

selection of intrahepatic vascular markers, followed by automatic extraction of intrahepatic vascular information); and integration (with integration of the liver and intrahepatic vascular system, 3D reconstruction was used to display the portal vein trunk, branch arrangement, and dominated region clearly from all directions in 3D).
