In Vivo Evaluation of Feeding Arteries of Tumors in Dorsal Sector of the Liver

With less blood loss and fewer postoperative complications, segmental resection is promoted and accepted by hepatic surgeons in the treatment of liver neoplasms (1-3). The dorsal sector of the liver, the parenchyma surrounding the vena cava, is quite independent of the remaining liver and deserves special attention in the segmental resections or the partition for transplantation. This part of the parenchyma forms a dorsal sector on its own and deserves special attention, because of the problems it poses to surgeons undertaking liver segmental resections or partition for transplantation (4). The identification of the dorsal sector of the liver and its detailed anatomy is of primary importance for surgical practice. Segmental transcatheter arterial chemoembolization (TACE) possesses markedly stronger anticancerous effect but much less damage to liver function; hence, its long-term effectiveness excels the conventional TACE in liver cancers treatment (5-7). A sufficient segmental TACE of the tumor in the dorsal sector depends on the identification of feeding arteries to the segment; however, the origin of hepatic arterial blood supplying to the dorsal sector is intricate and needs further research. Several studies have described the portal and biliary anatomy of the liver (4, 8). To our knowledge, the arterial anatomy of the dorsal sector of human liver has not been understood completely. In the present study, we retrospectively analyzed computed tomography (CT) and digital subtraction angiography (DSA) images of the patients with tumors in the dorsal sector of the liver. The hepatic arteries feeding the tumors in the dorsal sector were evaluated by DSA in living bodies. We believe that information from this study would be useful for understanding the arterial anatomy of the dorsal sector of the liver.

The objective of this study was to investigate the feeding arteries of tumors in dorsal sector of the liver.

The retrospective study was performed in accordance with approvals and the guidelines of ethical review board of our hospital. As the CT and DSA images of the patients were analyzed anonymously in the study, the ethical review board waived the need for written informed consent from the participants. CT and DSA images of the patients with tumors in the dorsal sector of the liver between August 2008 and May 2013 were analyzed retrospectively. The images were reviewed and interpreted by three radiologists with more than ten years of clinical experience, one surgeon, and one DSA technician. They analyzed all the images and then obtained consistent diagnosis of each case. Philips 8000 4-slice spiral CT was used (120 KV, 250 MAS) (Philips Healthcare, Cleveland, OH, USA), with a slice thickness of 5 mm. The enhanced scan was performed after bolus injection of 80 to 100 mL of Iohexol via a cubital vein (2-3 mL per second). The arterial phase, portal vein phase, and parenchymal phase scans were initiated at 20, 50, and 100 seconds after injection, respectively. DSA examinations and interventional treatments were performed under the Standardized Regulations of Interventional Treatments for Liver Cancers (Draft) (9). Siemens Polystar DSA device (Siemens Medical Solutions, Forchheim, Germany) was used for celiac artery, proper hepatic artery, and superior mesenteric artery angiography and indirect portography. For this purpose, 20 to 30 mL of iohexol was injected with a speed of 1.5 to 3 mL per second. The image acquisition was one to four frames per second. The time of visualization lasted 15 to 25 seconds. The definite diagnosis of hepatocellular carcinoma was made according to clinical diagnosis and staging criteria of primary hepatic carcinoma, established by Chinese Society of Liver Cancer (CSLC) (10). Liver metastasis was diagnosed by CT images and histopathologic analysis of primary tumor. To determine the Michels type of hepatic artery, we observed the vessels such as right hepatic artery, left hepatic artery, etc. (11). The localization diagnosis of tumors in the dorsal sector was determined by CT images based on the previous reports (Figure 1) (4, 12-14). The dorsal sector of the liver is located at the front and at the right side of the vena cava. The edges of the dorsal sector are as follows: segment I on the left side; right portal pedicle, segment Ⅷ and at times segment Ⅶ is in front of the dorsal sector; segment VII on the right side; The inferior vena cava at the back; and the terminal portions of the middle and right hepatic vein above (4). The DSA images were used to observe the hepatic artery branches including right anterior hepatic artery (RAHA), right posterior hepatic artery (RPHA), middle hepatic artery (MHA), left medial hepatic artery (LMHA), left lateral hepatic artery (LLHA), right hepatic artery (RHA), left hepatic artery (LHA), caudate hepatic artery (CaHA), and cystic artery (CyA). A scoring method was used to estimate each artery contribution to the tumor stain in dynamic DSA images. An artery contributing to > 75% of tumor stain was scored as 4 points, 50% to 75% as 3 points, 25% to 50% as 2 points, < 25% as 1 point, and 0% as 0 point (Figures 2 and 3). Dynamic DSA images of each patient were reviewed. The early phase images were used to determine the feeding arteries of the tumor (Figure 2). The scores of such arteries were evaluated according to their contributions to the tumor stain in the later phase images (Figure 3). The accumulative scores of each hepatic artery of eleven patients were used to evaluate the blood supply of feeding arteries to the tumors. Cases were excluded from the study if they had one or more of the followings: (a) liver with irregular outward appearance, eg, severe cirrhosis; (b) arterio-portal fistula; (c) arterio-venous fistula; (d) abnormal anastomotic or collateral arteries between left and right hepatic arteries; (e) a history of abdominal surgery before interventional procedure; (f) diffuse tumors in liver. The SPSS 11.0 (SPSS Inc, Chicago, Illinois, the USA) was used for statistical analysis. The case numbers of the feeding arteries of the tumors were compared by Cochran’s Q test. The scores of feeding arteries of the tumors were compared by test for several related samples (Friedman) and test for two related samples (Wilcoxon). P values < 0.05 were considered statistically significant.

Figure 1.

Hepatocellular carcinoma located in dorsal sector of the liver in computed tomography image.

Figure 2.

Feeding arteries in the same patient as Figure 1. Early phase digital subtraction angiography imaging revealed that the tumor was supplied by several branches of right hepatic artery (RHA) and left hepatic artery (LHA). The main blood of the tumor was provided. A, right posterior hepatic artery (RPHA). B, Caudate hepatic artery (CaHA). C, Left medial hepatic artery (LMHA).

Figure 3.

Diagram of scoring definition in the same patient as Figure 1 and 2. A, A feeding artery contributing to > 75% of tumor stain was scored as 4 points; B, 50% to 75% as 3 points; C, 25% to 50% as 2 points; and D, < 25% as 1 point. E, Right posterior hepatic artery (RPHA). F, Caudate hepatic artery (CaHA). G, Left medial hepatic artery (LMHA) were respectively scored as 2, 1, and 2 points in later phase of digital subtraction image of the patient.

This study included 11 patients, ten men and one woman, with the mean age of 53.9 years (range, 38-65 year) who had tumors in the dorsal sector of the liver. Eight cases were hepatocellular carcinoma and three were liver metastases. The primary tumors were colon cancer (n = 2) and gastric cancer (n = 1). The mean of maximum diameter of these tumors was 5.0 cm (range, 2.6-10.8 cm). According to the Michels classification of hepatic arterial anatomy, there were eight cases of type I, one case of type II, and one case of type III. Both the RHA and LHA originated directly from the celiac artery in one case. MHAs were revealed in nine cases. MHAs originated from RHA in seven cases, from LHA in one case, and from the proper hepatic artery (PHA) in one case. The scores of MHAs were cumulated to the corresponding RHA and LHA system in the current study. The data of the study revealed that the arterial blood of tumors in the dorsal sector originated from multiple arteries including RAHA, RPHA, CaHA, MHA, and LMHA (Table 1). The frequency and score of each arterial branch feeding the tumors was calculated (Tables 2 and 3). In this regard, the most prevalent feeding branch was RPHA followed by MHA. RPHA was seen in nine cases (81.8%) with 23 points in total. MHA was seen in eight cases (72.7%) with 17 points in total. The total scores of RHA branches and LHA branches were 51 and 11 points, respectively (Z = -2.764, P = 0.006, Wilcoxon).