(BQ) Part 2 book Master techniques in general surgery Hepatobiliary and pancreatic surgery presentation of content: Right and extended right hepatectomy, left and extended left hepatectomy, central hepatectomy, hepatic caudate resection, enucleation of hepatic lesions, hepatic segmental resections,... and other contents.
18 Hepatic Resection: General Considerations Jean-Nicolas Vauthey and Junichi Shindoh Introduction Resection is the first-line treatment in selected patients with primary or metastatic hepatic malignancies In recent decades, refinements in surgical techniques and in perioperative patient care have improved the safety of liver resection; however, the most important factor influencing outcomes after liver resection is the surgeon's knowledge of the basic surgical principles pertaining to the procedure Postoperative morbidity and mortality rates can be reduced by proper patient selection, attention to liver anatomy and volumetry, and use of the optimal approach and technique for resection At largevolume centers, the 90-day mortality rates after liver resection are now less than 5%, and the rate of complete resections with negative margins is approaching 90% These rates are not likely to be substantially further improved, especially as the limits of resectability are continually being pushed; therefore low morbidity rates and early recovery will have to be considered as the new primary endpoints In this chapter, we report the general principles pertaining to the safe and complete resection of liver tumors Preoperative Assessment In recent years, the eligibility criteria for liver resection have been expanded to include patients not previously deemed to be surgical candidates, such as those with multiple bilobar liver metastases from colorectal cancer and those with large or multinodular hepatocellular carcinoma (HCC) However, the current definition of resectability still requires that the surgeon be able to completely remove the tumor while preserving a sufficient remnant of healthy liver tissue to limit the risk of postoperative liver dysfunction This oncosurgical definition necessitates attention to (1) the extent of the tumor and (2) the quality and volume of the anticipated remnant liver after negative margins are achieved Evaluating Tumor Extent In recent years, advances in imaging technology have made the preoperative evaluation of liver tumors more precise, contributing to both the improvement and safety of liver resection tahir99 - UnitedVRG 2'l1 vip.persianss.ir 228 Part II Liver Figwa 18.1 Hepatic steatosis or fatty liver A: Severa macrovasicular steatosis, histologic appearance (lift) and features on con· trast-anhancad CT imaging (right) Note the perfusion differences btrtwaan the liver and spleen B: Unanhancad CT is considered mora reliable for assessing the dagraa af steatosis This scan shows severe (grade 3) macrovasicular steatosis Note that the unanhancad vassals are higher in attenuation than the surrounding liver parenchyma Helical computed tomography (CI') with a liver protocol (quadruple phase with rapid injection of 150 ml of intravenous contrast material and slice thickness of 2.5 to 5.0 mm through the liver) can accurately evaluate the extent of the tumor or tumors in the liver and each tumor's relationship with the biliary tract and vascular structures Three-dimensional reconstruction of CT images can be used to better assess the liver's segmental anatomy and volumetry Chest CT has replaced chest x-ray as the preferred modality for identifying lung metastases in patients with liver tumors The routine use of enhanced magnetic resonance imaging (MRI) has generally not been recommended because MRI has not been demonstrated to be more accurate than CI' for most patients and because it is less reliable for detecting extrahepatic disease, particularly in the chest or peritoneum However, MRI should be performed for further characterization of presumably benign or atypical liver tumors or when the contrast agents used for CT are contraindicated In addition, new MRI contrast agents are potentially very useful for delineating hepatic disease extent, particularly in the setting of hepatic steatosis (Figs 18.1, 18.2) Because of the improvements in image resolution mentioned above, laparoscopy is less frequently indicated to assess the extent of liver tumors, although additional hepatic disease may well be identified and is still used in selected patients to evaluate for extrahepatic disease, chronic liver disease, or hepatic injury associated with extended chemotherapy Although recommended by some surgeons as part of preoperative evaluation, positron emission tomography (PET) is not used routinely for primary liver cancer or liver metastases at all centers Importantly, PET-CT should not replace high-quality cr imaging combined with interpretation by a radiologist with hepatobiliary expertise PET-CT is not useful in patients who have received preoperative chemotherapy for colorect.al cancer liver metastases because the response to chemotherapy is associated with decreased PET sensitivity Evaluating Determinants of Postoperative Liver Function Liver function after liver resection depends on the quality of the liver parenchyma, the volume of the future liver remnant (FLR), and the regenerative capacity of the liver The risk of postoperative liver failure remains high after major or extended liver resection This risk should be estimated preoperatively to determine whether resection is safe and to optimize the postoperative outcome tahir99 - UnitedVRG vip.persianss.ir Chapter 11 Hepatic Resection: General Considerations 229 figure 18.2 A: MRI scan illustrating its utility in differentiating benign from malignant liver tumors T2weighted (tap) and postgadolinium {battolt) showing differential imaging features between a contiguous metastatic tumor II eft white circle) and a hemangioma !right yellow circle) Note the bright appearance on T2 and the peripheral nodular enhancement pattern that are characteristic of hemangiomata B: Contrast-enhanced CT (left) and MRI {right) images of a patient with hepatic colorectal metastases Fatty infiltration of the liver !steatosis) is apparent on the CT Multiple liver tumors seen on MRIIsrroWI) were poorly delineated on CT In patients with chronic liver disease, the functional reserve of the liver is assessed using composite scoring systems that include biologic data, such as the Child-Pugh classification system for liver disease (Table 18.1) Usually, only patients with ChildPugh class A disease are considered eligible for liver resection because postoperative mortality rates are higher for patients with higher Child-Pugh class, approaching 50o/o for those with Child-Pugh class C disease Since the presence of undiagnosed subclinical portal hypertension can considerably increase the risk associated with surgery, patients should be screened preoperatively for clinical signs of portal hypertension (for ascites, collateral venous circulation), biologic assessment (for platelet count nonnal) Ascites Encephalopa1hy (grade) >3.5