complex distribution, and variation because the small arter­ies of extrahepatic bile duct are the end of the celiac arteries. The variation of the celiac artery is complicated, especially the high variation rate of the hepatic artery and gallbladder artery, and characteristically complex distribution and varia­tion. Besides, there must be distortion in the information of the cadaveric cast specimen compared with the information of the living human body, and there may be variations in the blood supply of the extrahepatic bile duct under pathological conditions. It is vital to have a deep understanding of the characteristics of the blood supply and the distribution of extrahepatic bile ducts in healthy human beings and the path­ological conditions of the biliary tract. It is possible to pro­vide a precise individualized morphological basis for the rational selection of clinical biliary surgery schemes and the prevention of postoperative biliary complications. Therefore, it is crucial to solve the problem of how to obtain the three­dimensional display of extrahepatic bile duct blood supply in living human before the operation.

In the diagnosis and management of extrahepatic bile duct hemorrhage, it is necessary to deal with the anatomical characteristics of biliary blood supply. A 3D model can accu­rately display the parts of the extrahepatic bile duct and its blood supply distribution, as well as the location of the extra­hepatic bile duct hemorrhage, to guide the accurate ligation of the corresponding biliary blood supply artery. In the com­mon bile duct exploration, the 3D model of the extrahepatic bile duct and its blood supply can show whether there is a transverse supply artery in the anterior wall of the extrahe­patic bile duct, avoiding damage to the artery during bile duct incision, resulting in postoperative bile duct ischemic stenosis or complications such as bile leakage. In the jejunal anastomosis of the common bile duct, the 3D model can guide the site of anastomotic selection and avoid stenosis or bile leakage after ischemic choledochojejunostomy.

mentation methods, which can be classied into three cate­gories: threshold-based segmentation, edge-based segmentation, and region-based segmentation. Segmentation algorithms are generally based on two basic properties of gray level values: discontinuity and similarity. The pixels within the region usually have some similarities, while the pixels at the boundary between the regions generally have discontinuity. The most widely used segmentation method is region growing. It involves the selection of initial seed points on the CT tomographic image and determination of thresh­old values. The pixel values of the sequence maps within the threshold and the regions are segmented, and the three­dimensional reconstruction is performed. In image segmen­tation “dimensions” are not up down forward back type dimensions, but mathematically similar pixel values. Region growing uses formulae to decide similar pixels belong to one group not the neighboring group and form a “segment” (shape), you might have 5 types of tissue with denable image properties, If you are trying to segment them you could end up with very fractured images. The arteries that supply the extrahepatic bile duct are all terminal vessels with a small caliber. How to extract and segment them from CT data is a difcult problem.

There are two existing methods for the reconstruction of segmented 3D medical images: surface rendering (SR) and volume rendering (VR). The VR technique involves several rays passing through 3D volume data, without the need of going through an intermediate surface extraction, and many details of voxels can be preserved. VR can reproduce the real structure of the human anatomy more effectively and improve the delity of results. VR is superior to SR in terms of image quality; however, SR is better than VR in terms of interaction performance and algorithm efciency, at least on the current hardware platform. Since the VR algorithm is computation­ally intensive, its interactive performance is not always opti­mum, even by using high-performance computers. This issue can be addressed by using the segmentation method based on volume rendering interaction. Firstly, the volume rendering reconstruction is carried out. By adjusting the window width and window position, the 3D image of the tissue of immediate interest is obtained, the 3D seed points are obtained directly on the volume rendering image, and the region growth algo­rithm is applied. The growth process is displayed on the vol­ume rendering image; when growth stops, repairment can be carried out on the volume rendering 3D image by human– computer interaction. Especially for small blood vessels, local small blood vessels can be extracted by magnifying the ne blood vessels, extracting and segmenting the small blood vessels. This project enables tissue segmentation, especially more rened blood vessel segmentation, reaching the same resolution level as volume rendering. When the user is satis­ed with the current segmentation results, the results can be saved immediately, and the 3D surface rendering and recon-

ume rendered images, which is intuitive and accurate.

tion can be interrupted according to the growth process at

any time.

satised.

• The delicate parts can be amplied. The defect where the

The extrahepatic bile duct can be divided into upper and lower segments according to the region where the cystic duct ows into the extrahepatic bile duct. By observing and ana­lyzing the origin, course, and distribution of extrahepatic bile duct blood supply arteries in the 3D model, the following characteristics can be seen.

Blood Supply of Right Hepatic Artery The 3D model showed that the right hepatic artery originated from the

The 3D digital classication of extrahepatic bile duct blood supply was established according to the characteristics of the source and distribution of extrahepatic bile duct blood sup­ply in the 3D visualization model.

The incidence of hepatic artery variation is high, and the right hepatic artery is an important source of extrahepatic bile duct blood supply. It is of great clinical signicance to identify and protect the variant hepatic artery during the operation. For example, the 3D model of extrahepatic bile duct blood supply showed that the variant right hepatic artery originated from the superior mesenteric artery; the posterior superior pancreaticoduodenal artery issued branches, and its branches were close to the common bile duct, and the left edge of the common hepatic duct and ran upward. Finally, they converged with the variant right hepatic artery to form the left marginal artery of the extrahepatic bile duct (3 o’clock artery) and supplied the extrahepatic bile duct throughout (Fig. 9.21). The signicance of analyzing the variant extrahepatic blood supply artery by 3D technique lies

course, and distribution of extrahepatic bile duct blood sup-

ply in patients with extrahepatic bile duct obstructive dis­eases, can be obtained to help carry out individualized preoperative planning and surgical design. This provides individualized anatomical guidance for the rational selection of clinical biliary surgical plans.