The intersegmental plane of the liver is not always flat--tricks for anatomical liver resection

Segment 5 parenchymal sparing in extended left hepatectomy with respect to venous outflow-is it a feasible procedure?

BACKGROUND

Segment 5 (S5) sparing liver resection for cases that require an anatomic left trisectionectomy has not been reported yet. The authors intended to verify the outcome of S5-sparing extended left hepatectomy (ELH) in respect to venous outflow.

METHODS

All adult patients who underwent S5-sparing ELH between 2012 and 2017 in authors' institute have been enrolled in this study. S5-sparring ELH was defined as resection of S2, S3, S4, and S8 with or without S1. The surgery planning was based on the images from two-dimensional triphasic computed tomography and/or magnetic resonance imaging. A three-dimensional image reconstruction and liver volumetric study were performed retrospectively.

RESULTS

Out of 177 cases of major hepatic resection, only seven non-hilar cholangiocarcinoma patients underwent ELH during the study period. S5-sparing ELH was performed to five patients, in whom no tumor involvement in S5. The venous outflow of S5 has been maintained intraoperative, and S5 congestion has not been observed in all patients. Tailored management of the S5 venous outflow ensured an increase in functional remnant liver volume by 52.8% (range, 25.6 to 66.9%) by sparing of S5. A negative resection margin was achieved in all patients. One patient had postoperative bile leak requiring reoperation. No posthepatectomy liver failure (PHLF) has been observed.

CONCLUSION

S5-sparing ELH is technically feasible. Under the tailored management of S5 venous outflow, the functional future liver remnant can be increased. Further studies with larger sample size are needed to evaluate which circumstances the liver segment 5 could be preserved without venous reconstruction during the left extended hepatectomy.

Open Liver Resection, Laparoscopic Liver Resection, and Percutaneous Thermal Ablation for Patients with Solitary Small Hepatocellular Carcinoma (≤30 mm): Review of the Literature and Proposal for a Therapeutic Strategy

BACKGROUND

Patients with a single hepatocellular carcinoma (HCC) ≤3 cm and preserved liver function have the highest likelihood to be cured if treated. The most adequate treatment methods are yet a matter that is debated.

METHODS

We reviewed the literature about open anatomic resection (AR), laparoscopic liver resection (LLR), and percutaneous thermal ablation (PTA).

RESULTS

PTA is effective as resection for HCC < 2 cm, when they are neither subcapsular nor perivascular. PTA in HCC of 2-3 cm is under evaluation. AR with the removal of the tumor-bearing portal territory is recommended for HCC > 2 cm, except for subcapsular ones. In comparison with open surgery, LRR has better short-term outcomes and non-inferior long-term outcomes. LLR is standardized for superficial limited resections and for left-sided AR.

CONCLUSIONS

According to the available evidences, the following therapeutic proposal can be advanced. Laparoscopic limited resection is the standard for any subcapsular HCC. PTA is the first-line treatment for deep-located HCC < 2 cm, except for those in contact with Glissonean pedicles. Laparoscopic AR is the standard for deep-located HCC of 2-3 cm of the left liver, while open AR is the standard for deep-located HCC of 2-3 cm in the right liver. HCC in contact with Glissonean pedicles should be scheduled for resection (open or laparoscopic) independent of their size. Liver transplantation is reserved to otherwise untreatable patients or as a salvage procedure at recurrence.

Ethanol ablation for refractory bile leakage after complex hepatectomy

BACKGROUND

Only a few reports exist on the use of ethanol ablation for posthepatectomy bile leakage. The aim of this study was to assess the value of ethanol ablation in refractory bile leakage.

METHODS

Medical records of consecutive patients who underwent a first hepatobiliary resection with bilioenteric anastomosis between 2007 and 2016 were reviewed retrospectively, with special attention to bile leakage and ethanol ablation therapy. Bile leakage was graded as A/B1/B2 according to the International Study Group of Liver Surgery definition. Absolute ethanol was injected into the target bile duct during fistulography.

RESULTS

Of the 609 study patients, 237 (38·9 per cent) had bile leakage, including grade A in 33, grade B1 in 18 and grade B2 in 186. Left trisectionectomy was more often associated with grade B2 bile leakage than other types of hepatectomy (P < 0·001). Of 186 patients with grade B2 bile leakage, 31 underwent ethanol ablation therapy. Ethanol ablation was started a median of 34 (range 15-122) days after hepatectomy. The median number of treatments was 3 (1-7), and the total amount of ethanol used was 15 (3-71) ml. Complications related to ethanol ablation included transient fever (27 patients) and mild pain (13). Following ethanol ablation, bile leakage resolved in all patients and drains were removed. The median interval between the first ablation and drain removal was 28 (1-154) days.

CONCLUSION

Ethanol ablation is safe and effective, and may be a treatment option for refractory bile leakage.

The Pitfalls of Left Trisectionectomy or Central Bisectionectomy for Biliary Cancer: Anatomical Classification Based on the Ventral Branches of Segment VI Portal Vein Relative to the Right Hepatic Vein

BACKGROUNDS

Some patients have P6a running on the ventral side (Ventral-P6a), relative to the right hepatic vein (RHV).

STUDY DESIGN

Forty-one patients who underwent left trisectionectomy or central bisectionectomy for biliary cancer were enrolled. We compared the anatomical features using 3D images and surgical outcomes between patients with Ventral-P6a (n = 17) and those with P6a running on the dorsal side relative to the RHV (Dorsal-P6a; n = 25). Moreover, the liver volume by hand-tracing 2D axial images was compared to the volume calculated using the 3D images.

RESULTS

The frequency of complete exposure of RHV on the transection plane was less in Ventral-P6a (12 vs. 76%; p < 0.001), and the frequency of supraportal type of right posterior hepatic artery (RPHA, 29 vs. 4%, p = 0.020), the presence of inferior RHV (47 vs. 12%, p = 0.011), and the angle between the transection plane of segment VI and VII (S6-S7angle, 29.0° vs. 4.9°; p < 0.001) were greater in Ventral-P6a than in Dorsal-P6a. In Dorsal-P6a, the volume of posterior section calculated using 2D images was greater than that calculated using 3D images (404 vs. 370 mL; p = 0.004). The incidence of daily diuretic administration in Dorsal-P6a was greater than in Ventral-P6a (88 vs. 54%, p = 0.035).

CONCLUSION AND RELEVANCE

In Ventral-P6a, the complete exposure of RHV was rare in left trisectionectomy or central bisectionectomy. Surgeons should preoperatively recognize the course of RPHA, the presence of inferior RHV, and the S6-S7angle. In Dorsal-P6a, the volume of posterior section, which tended to be overestimated using 2D images, was smaller than that in Ventral-P6a.

Human liver territories: Think beyond the 8-segments scheme

Worldwide, compartmentalization of the human liver into portal venous territories today follows the eight-segments scheme credited to Couinaud. However, there are increasing reports of anatomical, radiological and surgical observations that contradict this concept. This paper presents a viewpoint that enhances understanding of these inconsistencies and can serve as a basis for customized liver interventions. Clin. Anat. 30:974-977, 2017. © 2017 Wiley Periodicals, Inc.

Clinical Anatomy of the Liver: Review of the 19th Meeting of the Japanese Research Society of Clinical Anatomy

Precise clinical knowledge of liver anatomy is required to safely perform a hepatectomy, for both open and laparoscopic surgery. At the 19th meeting of the Japanese Research Society of Clinical Anatomy (JRSCA), we conducted special symposia on essential issues of liver surgery, such as the history of hepatic segmentation, the glissonean pedicle approach, application of 3-D imaging simulation and fluorescent imaging using indocyanine green solution, a variety of segmentectomies including caudate lobectomy, the associating liver partition and portal vein embolization for stage hepatectomy and harvesting liver grafts for living donor liver transplantation. The present review article provides useful information for liver surgeons and anatomic researchers.

Venous drainage map of the liver for complex hepatobiliary surgery and liver transplantation

BACKGROUND

Inflow and outflow patency of the liver parenchyma is required to maximize the metabolic function of the liver. However, the definition and distribution of hepatic venous drainage regions has yet to be reported. The aim of this study was to define major hepatic venous tributaries and investigate the mean drainage volume of each territory.

METHODS

Three-dimensional (3D) simulations from the livers of 100 healthy donors were reviewed for living donor liver transplantation to determine the distribution of the significant hepatic venous tributaries and the drainage patterns of each segment.

RESULTS

The left hepatic vein (LHV), middle hepatic vein (MHV), and right hepatic vein (RHV) contributed a mean drainage of 20.7%, 32.7%, and 39.6% of the entire liver, respectively. Accessory hepatic veins accounted for remaining 7.0%. The middle right hepatic vein (MRHV) and inferior right hepatic vein (IRHV) accounted for a mean total drainage of 8.0% and 10.6%, respectively, when they present. In addition, major tributaries of hepatic veins were clearly detected, and their typical distributions were described.

CONCLUSIONS

Knowledge of hepatic venous territories is necessary for complex hepatobiliary surgery. This "venous drainage map" may provide useful information for complex liver surgery and transplantation.

Hepatocellular carcinoma: From clinical practice to evidence-based treatment protocols

Hepatocellular carcinoma (HCC) is one of the major malignant diseases in many healthcare systems. The growing number of new cases diagnosed each year is nearly equal to the number of deaths from this cancer. Worldwide, HCC is a leading cause of cancer-related deaths, as it is the fifth most common cancer and the third most important cause of cancer related death in men. Among various risk factors the two are prevailing: viral hepatitis, namely chronic hepatitis C virus is a well-established risk factor contributing to the rising incidence of HCC. The epidemic of obesity and the metabolic syndrome, not only in the United States but also in Asia, tend to become the leading cause of the long-term rise in the HCC incidence. Today, the diagnosis of HCC is established within the national surveillance programs in developed countries while the diagnosis of symptomatic, advanced stage disease still remains the characteristic of underdeveloped countries. Although many different staging systems have been developed and evaluated the Barcelona-Clinic Liver Cancer staging system has emerged as the most useful to guide HCC treatment. Treatment allocation should be decided by a multidisciplinary board involving hepatologists, pathologists, radiologists, liver surgeons and oncologists guided by personalized -based medicine. This approach is important not only to balance between different oncologic treatments strategies but also due to the complexity of the disease (chronic liver disease and the cancer) and due to the large number of potentially efficient therapies. Careful patient selection and a tailored treatment modality for every patient, either potentially curative (surgical treatment and tumor ablation) or palliative (transarterial therapy, radioembolization and medical treatment, i.e., sorafenib) is mandatory to achieve the best treatment outcome.

Novel 3-dimensional virtual hepatectomy simulation combined with real-time deformation

AIM: To develop a novel 3-dimensional (3D) virtual hepatectomy simulation software, Liversim, to visualize the real-time deformation of the liver.

METHODS: We developed a novel real-time virtual hepatectomy simulation software program called Liversim. The software provides 4 basic functions: viewing 3D models from arbitrary directions, changing the colors and opacities of the models, deforming the models based on user interaction, and incising the liver parenchyma and intrahepatic vessels based on user operations. From April 2010 through 2013, 99 patients underwent virtual hepatectomies that used the conventional software program SYNAPSE VINCENT preoperatively. Between April 2012 and October 2013, 11 patients received virtual hepatectomies using the novel software program Liversim; these hepatectomies were performed both preoperatively and at the same that the actual hepatectomy was performed in an operating room. The perioperative outcomes were analyzed between the patients for whom SYNAPSE VINCENT was used and those for whom Liversim was used. Furthermore, medical students and surgical residents were asked to complete questionnaires regarding the new software.

RESULTS: There were no obvious discrepancies (i.e., the emergence of branches in the portal vein or hepatic vein or the depth and direction of the resection line) between our simulation and the actual surgery during the resection process. The median operating time was 304 min (range, 110 to 846) in the VINCENT group and 397 min (range, 232 to 497) in the Liversim group (P = 0.30). The median amount of intraoperative bleeding was 510 mL (range, 18 to 5120) in the VINCENT group and 470 mL (range, 130 to 1600) in the Liversim group (P = 0.44). The median postoperative stay was 12 d (range, 6 to 100) in the VINCENT group and 13 d (range, 9 to 21) in the Liversim group (P = 0.36). There were no significant differences in the preoperative outcomes between the two groups. Liversim was not found to be clinically inferior to SYNAPSE VINCENT. Both students and surgical residents reported that the Liversim image was almost the same as the actual hepatectomy.

CONCLUSION: Virtual hepatectomy with real-time deformation of the liver using Liversim is useful for the safe performance of hepatectomies and for surgical education.

Anatomical Liver Resections Guided by 3-Dimensional Parenchymal Staining Using Fusion Indocyanine Green Fluorescence Imaging

OBJECTIVE

To investigate the feasibility and efficacy of anatomical liver resection (ALR) guided by fused images comprising a macroscopic view and indocyanine green fluorescence imaging (fusion IGFI).

BACKGROUND

ALR is established in treating hepatocellular carcinoma or other malignancies to achieve curability and functional preservation. However, the conventional demarcation technique (CDT) marks only the organ surface and sometimes fails to execute a completely valid demarcation.

METHODS

Twenty-four consecutive ALRs for focal liver malignancy were studied using fusion IGFI. Indocyanine green was administered systemically after selective inflow clamping in 12 patients or by portal puncture and direct injection in 12 patients, and we compared demarcation findings between fusion IGFI and CDT. The strength of contrast between target and nontarget areas was quantitatively calculated as contrast index and compared between IGFI and CDT according to injection technique or state of the liver surface.

RESULTS

Fusion IGFI achieved valid demarcation in 23 of 24 patients (95.8%), whereas CDT achieved valid demarcation in only 10 patients (41.7%) (P < 0.0001). The contrast index of fusion IGFI was 0.81 (0.18-2.51), which was significantly higher than that of CDT at 0.12 (0.01-0.42) (P < 0.0001), and the same result was obtained regardless of the injection method or liver surface state used. ALR was conducted referring to 3-dimensional staining of target parenchyma, with no related perioperative adverse events.

CONCLUSIONS

Fusion IGFI is a safe imaging technique for ALR that attained valid 3-dimensional parenchymal demarcation with better feasibility and clearer demarcation than CDT.

Sustained methylene blue staining to guide anatomic hepatectomy for hepatocellular carcinoma: Initial experience and technical details

BACKGROUND

The boundary of the target hepatic segment within the liver parenchyma cannot be marked by the use of a conventional anatomic hepatectomy approach. This study describes a novel methylene blue staining technique for guiding the anatomic resection of hepatocellular carcinoma (HCC).

METHODS

Between February 2009 and February 2012, anatomic hepatectomy was performed in 106 patients with HCC via a novel, sustained methylene blue staining technique. Sustained staining was achieved by injecting methylene blue into the distal aspect of the portal vein after exposing Glisson's sheath. The hepatic pedicle was immediately ligated, and the hepatic parenchymal transection was performed along the interface between methylene blue stained tissue and unstained tissue.

RESULTS

Anatomic hepatectomies included subsegmentectomy (n = 16), monosegmentectomy (n = 57), multisegmentectomy (n = 27), and hemihepatectomy (n = 6). The portal vein was injected successfully with methylene blue in 100% of cases, and complete staining of the target hepatic segment was achieved in 98 of 106 (92.5%) cases. Mean intraoperative bleeding was 360 ± 90 mL, and the postoperative complication rate was 24.5% (26/106). No perioperative mortality occurred. Operative margins were all negative on pathologic examination. Mean duration of postoperative follow-up was 40 months (range, 24-60). No local recurrence (around the operative margin) occurred.

CONCLUSION

This novel technique of achieving sustained staining by injecting methylene blue then immediately ligating the hepatic pedicle is simple and feasible. It can guide the selection of the operative margin during hepatic parenchyma transection to improve the accuracy of anatomic hepatectomy for the treatment of HCC.

A study of the right intersectional plane (right portal scissura) of the liver based on virtual left hepatic trisectionectomy

BACKGROUND

Left hepatic trisectionectomy is a challenging procedure. For an anatomically correct resection, it is necessary to have understanding of the right intersectional plane; however, little is known on this issue. The purpose of this study was to investigate the 3D anatomy of the right intersectional plane and to enable safe and precise left trisectionectomy.

METHODS

A virtual left trisectionectomy was performed using 3D-processing software, in patients who underwent computed tomography. The reconstructed images were reviewed, and attention was paid to the extent of the right hepatic vein (RHV) exposure on the transected plane and the type of the inferior right hepatic vein (IRHV).

RESULTS

Of the 200 study patients, 109 (54.5 %) patients showed complete exposure of the RHV on the transected plane, whereas the remaining 91 exhibited partial exposure. In the 109 patients with complete exposure, 58 (53.2 %) patients had no IRHV and the remaining 51 had a small IRHV. None of the patients had a large IRHV. In contrast, of the 91 patients with partial exposure, only 10 (11.0 %) patients had no IRHV, 35 (38.5 %) had a small IRHV, and 46 (50.5 %) patients had a large IRHV. The incidence of IRHV types was significantly different between the two groups (P < 0.001).

CONCLUSIONS

The RHV does not always run along the right intersectional plane, i.e., the vein is not always fully exposed on the transected plane even after anatomically correct left trisectionectomy. The extent of the RHV exposure is closely related to the type of the IRHV.

A measure to assess the ablative margin using 3D-CT image fusion after radiofrequency ablation of hepatocellular carcinoma

OBJECTIVES

To examine the feasibility of three-dimensional computed tomography (3D-CT) image fusion in facilitating assessment of the ablative margin (AM) after radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC).

METHODS

This study involved 75 patients with solitary HCC who underwent RFA. The AM was evaluated using 3D-CT image fusion. All cases were categorized into two groups based on the extent of the AM: in Group A, sufficient AM was obtained, which was greater than or equal to 5 mm; in Group B, the lesion was also ablated successfully, but a 5 mm AM was not obtained.

RESULTS

3D-CT Image Fusion was performed on 36 and 39 patients in Group A and Group B, respectively. The 1, 3, 5 year RFS was 87.6%, 63.2%, 50.6% for Group A, and 77.2%, 51.5%, 35.6% for Group B, respectively (P = 0.042); the corresponding OS was 94.3%, 73.8%, 64.6%, and 86.2%, 60.5%, 47.6%, respectively (P = 0.046). Multivariate analysis showed that the AM (P = 0.048, HR = 2.15, 95% CI 1.01-4.60) and Pre-NLR were independent prognostic factors for PFS.

CONCLUSIONS

3D-CT image fusion is a feasible and useful method to evaluate the AM after RFA of HCC.

Precise anatomical resection of the ventral part of Segment VIII

•

Anatomical resection of S8vent is generally considered a demanding procedure.

•

There are no accurate methods to identify the demarcation line inside the liver by far.

•

We proposed a new method to divide the intersegmental plane by exposing and following the small tributaries of hepatic vein near the liver surface.

•

This method is time-consuming, but it is an effective way to divide the intersegmental plane.

INTRODUCTION

Anatomical resection of the ventral part of Segment VIII (S8vent) is demanding and there are no accurate methods to identify the demarcation line inside the liver. The current authors have proposed a method to solve the problem.

PRESENTATION OF CASE

The tumor was located in the S8vent and was 4 cm in size. One tributary of the middle hepatic vein (MHV), designated V8i, was running between S8vent and the dorsal part of Segment VIII (S8dor). Another tributary of the MHV, designated V8-5i, was running between S8vent and the ventral part of S5 (S5vent). About 5 ml of indigo carmine dye was injected into the proximal part of P8vent. After the small tributary of V8-5i was exposed, it was followed all the way to the main trunk of the MHV. The portal pedicle of S8vent was then ligated and divided. Next, the V8i was gradually exposed from the distal MHV to its trunk.

DISCUSSION

A recent study showed that the subsegmental border visualized between the ventral and dorsal region always coincided with the plane of V8i, so the subsegmental plane can be divided along with V8i by preserving the very small tributaries near the liver surface and following them to determine where they meet as they run into V8i. Also, the landmark vein of V8-5i in the transverse S8–S5 intersegmental plane was determined for the first time.

CONCLUSION

Proposed here is a more accurate method of dividing the liver parenchyma along the intersegmental and intersubsegmental demarcation.

The determination of bile leakage in complex hepatectomy based on the guidelines of the International Study Group of Liver Surgery

BACKGROUND

The International Study Group of Liver Surgery (ISGLS) has defined bile leakage as a drain fluid-to-serum total bilirubin concentration (TBC) ratio (the bilirubin ratio) ≥ 3.0. The aim of the present study was to determine the clinical significance of this definition, and to outline characteristics of bile leakage in complex hepatectomy.

METHODS

The TBCs of the serum and drain fluid were measured on postoperative days (POD) 1, 3, and 7 in 241 patients who had undergone hepatobiliary resection. The validation of the bilirubin ratio and predictors of bile leakage were retrospectively assessed.

RESULTS

Grade A, B, or C bile leakage was found in 23 (9.5 %), 66 (27.4 %), and 0 patients, respectively. The median duration of drainage was 27 days in grade B bile leakage. The sensitivity and specificity of the bilirubin ratio for detecting grade B bile leakage were 59 and 87 %, respectively. The area under the receiver operating characteristics curve of the drain fluid TBC on POD 3 had the highest predictive value: 68 % sensitivity and 76 % specificity for a drain fluid TBC of 3.7 mg/dL. The multivariate analysis demonstrated that operative time, left trisectionectomy, bilirubin ratio, and TBC of the drain fluid on POD 3 were independent predictors of grade B bile leakage.

CONCLUSIONS

In complex hepatectomy, bile leakage develops most frequently after left trisectionectomy and often results in a refractory clinical course. The ISGLS biochemical definition is valid, and a combination of bilirubin ratio and drain fluid TBC may enhance risk prediction for grade B bile leakage.

Role of surgery in colorectal cancer liver metastases

Colorectal carcinoma (CRC) is the third most common cancer, and approximately 35%-55% of patients with CRC will develop hepatic metastases during the course of their disease. Surgical resection represents the only chance of long-term survival. The goal of surgery should be to resect all metastases with negative histological margins while preserving sufficient functional hepatic parenchyma. Although resection remains the only chance of long-term survival, management strategies should be tailored for each case. For patients with extensive metastatic disease who would otherwise be unresectable, the combination of advances in medical therapy, such as systemic chemotherapy (CTX), and the improvement in surgical techniques for metastatic disease, have enhanced prognosis with prolongation of the median survival rate and cure. The use of portal vein embolization and preoperative CTX may also increase the number of patients suitable for surgical treatment. Despite current treatment options, many patients still experience a recurrence after hepatic resection. More active systemic CTX agents are being used increasingly as adjuvant therapy either before or after surgery. Local tumor ablative therapies, such as microwave coagulation therapy and radiofrequency ablation therapy, should be considered as an adjunct to hepatic resection, in which resection cannot deal with all of the tumor lesions. Formulation of an individualized plan, which combines surgery with systemic CTX, is a necessary task of the multidisciplinary team. The aim of this paper is to discuss different approaches for patients that are treated due to CRC liver metastasis.

Three-dimensional volumetry in 107 normal livers reveals clinically relevant inter-segment variation in size

BACKGROUND

The anatomic resection of Couinaud's segments is one of the key techniques in liver surgery. However, the territories and volumes of the eight segments are not adequately assessed based on portal branching.

METHODS

Three-dimensional (3D) perfusion-based volumetry was performed in 107 normal livers. Based on Couinaud classification, the portal branches were identified and the volumes of each segment were calculated. The relationships between branching patterns of the portal veins and segmental volumes were assessed.

RESULTS

In descending order of volume, median volumes of segments VIII, VII, IV, V, III, VI, II and I were recorded. Segment VIII was the largest, accounting for a median of 26.1% (range: 11.1-38.0%) of total liver volume (TLV), whereas segments II and III each represented <10% of TLV. In 69.2% of subjects, the portal branches of segment V diverged from the trunk of the branches of segment VIII. No relationship was found between branching type and segment volume.

CONCLUSIONS

The territories and volumes of Couinaud's segments vary among segments, as well as among individuals. Detailed 3D volumetry is useful for preoperative evaluations of the dissection line and of future liver remnant volume in anatomic segmentectomy.

Anatomy of the liver: an outline with three levels of complexity--a further step towards tailored territorial liver resections

The vascular anatomy of the liver can be described at three different levels of complexity according to the use that the description has to serve. The first--conventional--level corresponds to the traditional 8-segments scheme of Couinaud and serves as a common language between clinicians from different specialties to describe the location of focal hepatic lesions. The second--surgical--level, to be applied to anatomical liver resections and transplantations, takes into account the real branching of the major portal pedicles and of the hepatic veins. Radiological and surgical techniques exist nowadays to make full use of this anatomy, but this requires accepting that the Couinaud scheme is a simplification, and looking at the vascular architecture with an unprejudiced eye. The third--academic--level of complexity concerns the anatomist, and the need to offer a systematization that resolves the apparent contradictions between anatomical literature, radiological imaging, and surgical practice. Based on the real number of second-order portal branches that, although variable averages 20, we submit a system called the "1-2-20 concept", and suggest that it fits best the number of actual--as opposed to idealized--anatomical liver segments.

Virtual liver resection: computer-assisted operation planning using a three-dimensional liver representation

In liver surgery, understanding the complicated liver structures and a detailed evaluation of the functional liver remnant volume are essential to perform safe surgical procedures. Recent advances in imaging technology have enabled operation planning using three-dimensional (3D) image-processing software. Virtual liver resection systems provide (1) 3D imaging of liver structures, (2) detailed volumetric analyses based on portal perfusion, and (3) quantitative estimates of the venous drainage area, enabling the investigation of uncharted fields that cannot be examined using a conventional two-dimensional modality. The next step in computer-assisted liver surgery is the application of a virtual hepatectomy to real-time operations. However, the need for a precise alignment between the preoperative imaging data and the intraoperative situation remains to be adequately addressed, since the liver is subject to deformation and respiratory movements during the surgical procedures. We expect that the practical application of a navigation system for transferring the preoperative planning to real-time operations could make liver surgery safer and more standardized in the near future.

Perioperative chemotherapy and liver resection for hepatic metastases of colorectal cancer

Surgical resection has played a major role in the treatment for colorectal liver metastases. The safety and efficacy of surgery for liver metastasis are obvious, although there are some differences between the western countries and Japan concerning the surgical indication, procedures, timing of chemotherapies in a perioperative period, and treatment of a primary disease. In future, long-term outcomes after surgical resection for colorectal liver metastases would be expected to be prolonged by combination of surgery and chemotherapies.

Surgical resection for small hepatocellular carcinoma in cirrhosis: the Eastern experience

Detection of small Hepatocarcinoma (HCC) by screening of high-risk populations is important to increase the percentage of patients suitable for curative treatment, which would lead to prolongation of the mean survival of patients with HCC. It should be remembered that small HCC is not always necessarily equivalent to early HCC as defined histologically. With recent advances in diagnostic imaging modalities, including contrast-enhanced ultrasonography and magnetic resonance imaging with liver-specific contrast enhancement, accurate differential diagnosis of early HCCs from dysplastic nodules has become possible. Because a certain proportion of small HCCs is known to show microscopic vascular invasion, surgical resection would be the treatment of first choice. To minimize potential microscopic invasion, anatomic resection and/or resection with a wide margin should be performed, while preserving liver function to the maximum extent possible. Surgical resection, however, cannot prevent multicentric occurrence of HCC, which remains a major issue precluding curative treatment of HCC.

Tzeng CW, Vauthey JN. Portal vein embolization for hepatocellular carcinoma

Portal vein embolization (PVE) improves the safety of major hepatectomy through hypertrophy of the future liver remnant (FLR), atrophy of the liver volume to be resected, and improvement in patient selection. Because most patients with hepatocellular carcinoma (HCC) have liver parenchymal injury due to underlying viral hepatitis or alcoholic liver fibrosis/cirrhosis, indication of PVE is relatively complex and sequential procedures, including transarterial chemoembolization, are required to maximize the effect of PVE as well as to minimize tumor progression due to increased arterial flow after PVE. PVE is currently indicated for patients with relatively well-preserved hepatic function [Child-Pugh A and indocyanine green tolerance test (ICG-R15) <20%) to achieve minimal FLR volume for safe major hepatectomy. FLR volume >40% is the minimal requirement for patients with chronic hepatitis or cirrhosis, and further strict criteria (FLR volume >50%) have been recommended for patients with marginal liver functional reserve (ICG-R15, 10-20%). Recent clinical results have suggested that PVE can be safely performed in patients with HCC and that it contributes to improved survival after major hepatectomy.

Resection of segment VIII for hepatocellular carcinoma

Background

Anatomical resection of segment VIII (SVIII) is technically demanding. Only two small studies have published short-term outcomes. The aim of the present study was to evaluate short- and long-term outcomes after anatomical resection involving SVIII for hepatocellular carcinoma (HCC), and to compare long-term outcomes with those after non-anatomical resection of SVIII.

Methods

Outcomes after anatomical resection of SVIII or its subsegments for HCC were compared with those in patients who underwent primary non-anatomical resection of SVIII during the same period.

Results

A total of 154 patients underwent anatomical resection involving SVIII and 122 had non-anatomical resection. In patients undergoing anatomical resection, the preoperative indocyanine green retention rate at 15 min ranged from 2·9 to 32·2 (median 13·6) per cent, and was 10 per cent or more in 109 patients (70·8 per cent). Median duration of operation and blood loss were 378 min and 705 ml respectively. There were no postoperative deaths, but major adverse events occurred in ten patients (6·5 per cent). The cumulative 5-year recurrence-free and overall survival rates were 28·5 and 79·6 per cent, which were significantly better than rates of 19·4 and 64·8 per cent respectively after non-anatomical resection (P = 0·036 and P &lt; 0·001).

Conclusion

Complete resection of SVIII or its subsegments can be performed safely and the long-term outcomes seem acceptable. This can be a curative procedure for HCC, especially in patients with limited liver function reserve, in whom right hepatectomy or right paramedian sectorectomy might otherwise be needed.

Vascular architecture in anomalous right-sided ligamentum teres: three-dimensional analyses in 35 patients

BACKGROUND

Right-sided ligamentum teres (RSLT) is a congenital anomaly that is sometimes encountered during hepatobiliary surgeries. However, a valid protocol for describing the segmental anatomy of livers with RSLT has not been established, and confusions or anatomic misunderstandings have been a major problem.

METHODS

The vascular architecture and morphological characteristics were investigated in 35 livers with RSLT using three-dimensional (3D) simulations.

RESULTS

Couinaud's four sectors and three hepatic veins were clearly distinguished in the liver with RSLT using 3D simulations. The ligamentum teres was connected with the right paramedian portal pedicle, and the long axis of the cystic fossa was always observed on the left of the ligamentum teres in all 35 livers. However, when the main portal scissura was visualized using 3D simulation, the gallbladder was always located on the border of either side of the hemilivers, and the malposition of the gallbladder was not confirmed.

CONCLUSIONS

Although the right-sided components of the livers are well developed as a result of the right-dominant distribution of the feeding vessels in livers with RSLT, the basic segmental structure defined by the four sectors and the three hepatic veins are as well preserved as those in the typical liver anatomy.