Percentage of Future Liver Remnant Volume Before Portal Vein Embolization Influences the Degree of Liver Regeneration After Hepatectomy

Background

Clinical determinants of liver regeneration induced by portal vein embolization (PVE) and hepatectomy remain unclear. The aims of this study were to investigate how liver regeneration occurs after PVE followed by hepatectomy and to determine which factors strongly promote liver regeneration.

Methods

Thirty-six patients who underwent both preoperative PVE and major hepatectomy were enrolled in this study. Percentage of future liver remnant volume before PVE (%FLR-pre) was compared with the remnant liver volume after PVE (%FLR-post-PVE) and on postoperative day 7 after hepatic resection (%FLR-post-HR). Clinical indicators contributing to liver regeneration induced by both PVE and hepatectomy were examined by logistic regression analysis.

Results

PVE and hepatectomy caused a two-step regeneration. FLR-pre, FLR-post-PVE, and FLR-post-HR were 448, 579, and 761 cm³, respectively. The %FLR-pre was significantly associated with liver regeneration induced by both PVE and hepatectomy (r?=?0.63, p?<?0.0001). Multiple regression analysis showed that only %FLR-pre was independently correlated with posthepatectomy liver regeneration (p?=?0.027, odds ratio?=?13.8).

Conclusion

After PVE and the subsequent hepatectomy, liver regeneration was accomplished in a two-step manner. Liver regeneration was strongly influenced by the %FLR-pre.     

The diagnostic value of 99m-Tc GSA scintigraphy for liver function and remnant liver volume in hepatic surgery: a retrospective observational cohort study in 27 patients

Background

The aim was to analyze hepatic hypertrophy after portal vein embolization (PVE) and Associating Liver Partition with Portal vein ligation for Staged hepatectomy (ALPPS) to determine whether clinical circumstances associated with major hepatic resections correlated with remnant growth.

Methods

Data was abstracted from a retrospectively maintained database on 27 patients undergoing hepatic resection followed by PVE and the ALPPS procedure between October 1, 2007 and December 31, 2016. The increasing rate of liver volume and remnant liver LU15 was defined as the percentage-point difference between the liver volume and remnant liver LU15 before and after the intervention or surgery. And correlation between kinetic growth rate (KGR) of liver and future remnant liver volume or remnant liver LU15 was analyzed.

Results

The degree of hypertrophy (DH) of volume and LU15 was significantly greater after ALPPS (volume: 40.3% and LU15: 65.0%) than after PVE (volume: 22.7% and LU15: 48.8%) (P <?0.05). KGR of volume and LU15 was significantly greater after ALPPS (volume: 19.0 cm³/day and 2.00%/day) (LU15: 0.61 /day and 1.82%/day) than after PVE (volume: 3.89 cm³/day and 0.42%/day) (LU15: 0.19 /day and 0.63%/day) (P <?0.001). An inverse correlation between KGR and initial remnant liver volume was observed. And a positive correlation between KGR and LU15 was observed.

Conclusion

Future remnant liver volume and KGR was greater after the ALPPS procedure than after PVE. Liver hypertrophy is related to the expected remnant liver volume and total liver function. This study suggested that total liver function and initial remnant liver volume might be a new indication of hepatectomy after PVE and ALPPS in the case of insufficient remnant liver volume.

     

Inferior Right Hepatic Vein-preserving Major Right Hepatectomy for Hepatocellular Carcinoma in Patients with Significant Fibrosis or Cirrhosis

Background

Liver resection represents a most effective treatment for hepatocellular carcinoma (HCC). The extent of hepatectomy for HCC involves maintaining a tricky balance between radical resection of tumors and preservation of sufficient liver parenchyma. Generally, removal of the right hepatic vein often involves resection of the whole posterior right lobe, which may prevent patients with impaired liver function from maintaining a functional reserve and could also limit the future liver remnant from curative hepatectomy. As a common anatomic variation, preservation of the inferior right hepatic vein (IRHV) may enable preservation of liver segment 6, even when the right hepatic vein has to be removed. In the present study, we report our experience with IRHV-preserving major right hepatectomy.

Methods

From February 2009 to December 2011, eight trisegmentectomies 5-7-8 and two segmentectomies 4-5-7-8 were performed with the IRHV-sparing technique on patients with HCC and significant fibrosis or cirrhosis. Data including demographic information, preoperative evaluations, postoperative outcomes, and follow-up results were collected and evaluated.

Results

All patients survived and recovered from hepatectomy. The incidence of complications was higher in cirrhotic patients. The 1-year overall survival rate was 80 %, and the 1-year disease free survival rate was 60 %.

Conclusions

IRHV-preserving major right hepatectomy increases the resectability of HCC. Intraoperative ultrasonography is recommended to facilitate protection of the IRHV. This technique is safe with careful preoperative evaluation and meticulous perioperative care. The short-term outcome of IRHV-preserving liver resections is satisfactory.     

Effect of Donor Right Hepatectomy on Splenic Volume and Platelet Count for Living Donor Liver Transplantation

Background

Donor hepatectomy for living donor liver transplantation accompanies physio-morphological changes of the liver and spleen. Therefore, the long-term consequences of these organs should be characterized to ensure donor's safety.

Methods

A total of 382 right liver harvests for liver transplantation were performed from October 2000 to February 2011. Clinical parameters across donor operations were compared, and the associations were investigated.

Results

The remaining liver grew continually, reaching 81.5?±?11.2 % of the entire liver until 6 months after donation. The spleen grew to 143.1?±?28.8 % of the pre-donation value within 1 week after surgery, and thereafter, its size decreased gradually to 130.6?±?25.1 % at 6 months. At 6 months post-donation, 48.1 % (114/237) of donors showed an increase of ≥30 % in splenic volume, and 15.9 % (50/315) of donors exhibited a decrease of ≥30 % in platelet count. However, patients with splenic enlargement and/or decrease in platelet count at 6 months post-donation were not different in liver function, liver regeneration, or overall complications.

Conclusions

Although splenic enlargement and/or decrease in platelet count can persist for more than 6 months after donation in patient population after donor right hepatectomy, such a change did not impact donor's safety.     

Accuracy of preoperative automatic measurement of the liver volume by CT-scan combined to a 3D virtual surgical planning software (3DVSP)

Background

Liver volumetry is a critical component of safe hepatic surgery, in order to minimize the risk of postoperative liver failure. Liver volumes can be calculated routinely using the time-consuming gold standard method of manual volumetry. The current work sought to evaluate an alternative automatic technique based on a novel 3D virtual planning software, and to compare it to the manual technique.

Methods

A prospective study of patients undergoing liver resection was conducted. Every patient had a pre and 2-day postoperative CT-scan. For each patient, total, remnant and resected volumes were calculated manually and automatically. Planes of resection were verified by a hepatobiliary surgeon and compared with postoperative volumes. Paired t-tests and correlation coefficients were calculated.

Results

A major hepatectomy was carried out in 36/43 patients. The automatic TLV (1,759 mL) and the manual TLV (1,832 mL) were significantly different (p < 0.001), but extremely highly correlated (r = 0.989). The percentages of preoperative RLV (manual 58.5 %, automatic 58.9 %) were similar, with an excellent correlation of 0.917. The preoperative RLV were matched with the 2-day postoperative RLV showing a significant difference (p = 0.0301). The resected volumes using both techniques (871 and 832 mL) were compared with the resected specimen volume (670 mL), showing a significant difference (p < 0.001) but a high degree of correlation (r = 0.874).

Conclusion

The 3D virtual surgical planning software is accurate and reliable in determining the total liver and future remnant liver volumes. This technique demonstrates a good correlation with the manual technique. Future work will be required to confirm these findings and to evaluate the clinical value of the three-dimensional planning platform.     

A modified liver-hanging maneuver focusing on the ligamentum venosum for left hepatic lobectomy

Purpose

The liver-hanging maneuver (LHM) is a useful technique in major hepatectomy. We made modifications to this technique with special reference to the ligamentum venosum for performing a left hepatectomy (LH). The aim of this study was to clarify the usefulness of our new technique.

Methods

Between August 2007 and May 2009, five patients underwent LH using our modified LHM and 12 patients underwent LH using a conventional procedure. The two groups were compared in terms of the patient characteristics, preoperative hepatic functions, surgical records, and outcomes.

Results

The characteristics and preoperative hepatic function tests were similar between the modified LHM and non-LHM groups. Intraoperative blood loss was significantly reduced in the modified LHM group compared with the non-LHM group (193?±?133 vs. 375?±?167?ml, P?Conclusion Our modified LHM can reduce the intraoperative blood loss during LH, and our results have shown the usefulness of this modified technique for LH.     

Does Preoperative Portal Vein Embolization Have Any Impact on the Outcome of Right-Side Hepatectomy for Klatskin Tumor?

Background and Aim

The clinical usefulness of portal vein embolization (PVE) for Klatskin tumor is not well established. The authors explored the change in liver volume and function before and after major hepatectomy and evaluated the effect of PVE.

Methods

Thirty-three consecutive patients who underwent right hepatectomy with an initial future liver remnant (FLR)?≤?30 % for Klatskin tumors at Seoul National University Hospital were included.

Results

Eleven patients underwent PVE, and eight patients received right trisectionectomy. PVE induced a mean FLR increase of 19.3 % after a mean of 15.8 days. At postoperative month 1, liver volume and liver hypertrophy ratio was comparable between PVE and no-PVE group. For patients with an initial FLR?≤?20 %, postoperative liver hypertrophy rate of PVE group was comparable to no-PVE group. Liver function tests were not affected by PVE or the initial FLR. Postoperative liver hypertrophy ratio was negatively correlated with the initial FLR (hypertrophy ratio (%)?=?326.7–0.4×initial FLR (ml), P?=?0.001). There was no severe PVE-related morbidity, and postoperative morbidity rate was comparable in PVE and no-PVE group.

Conclusion

The postoperative liver hypertrophy ratio, final liver volume, or liver function tests were not affected by PVE. Postoperative liver hypertrophy was related to the initial FLR.     

Comparison of Laparoscopy-Assisted and Open Donor Right Hepatectomy: a Prospective Case-Matched Study from China

Background

Laparoscopy-assisted hepatectomy is a new minimally invasive approach for graft harvesting in living donors. Only a few liver transplant centers have introduced this surgical procedure.

Methods

A prospective case-matched study was conducted on 25 consecutive donors who underwent laparoscopy-assisted donor right hepatectomy (LADRH) between July 2011 and March 2013 at our transplant center. These donors were matched 1:1 according to age, gender, and body mass index with 25 donors who underwent open donor right hepatectomy (ODRH).

Results

LADRH was successfully performed in all 25 of the donors. Donor complications, estimated blood loss, and operative time were similar between the groups. Hospital stay and periods of analgesic use were significantly shorter in the LADRH group [7.0?±?1.4 (LADRH) vs 8.7?±?2.4 (ODRH), p?=?0.003, and 2.4?±?1.0 (LADRH) vs 3.2?±?1.0 (ODRH), p?=?0.011, respectively). The total in-hospital cost is higher with LADRH, primarily due to the additional material costs for LADRH. Finally, there were no differences in graft size, graft survival, or recipient complications between the two groups.

Conclusion

The results of this study show that LADRH is a feasible and safe procedure compared with ODRH. Although higher material costs for laparoscopic assisted procedures are inevitable, LADRH may have an advantage over ODRH by causing less pain and facilitating earlier recovery. Efforts can be made to improve the technical success of LADRH for some overweight donors.     

Preoperative Hepatitis B Virus DNA Level is a Risk Factor for Postoperative Liver Failure in Patients Who Underwent Partial Hepatectomy for Hepatitis B-Related Hepatocellular Carcinoma

Objective

Our objective was to explore the short-term effects of preoperative serum hepatitis B virus DNA level (HBV DNA) on postoperative hepatic function in patients who underwent partial hepatectomy for hepatitis B-related hepatocellular carcinoma (HCC).

Methods

The clinical data of 1,602 patients with hepatitis B-related HCC who underwent partial hepatectomy in our department were retrospectively studied. The patients were divided into three groups according to their preoperative HBV DNA levels: group A <200 IU/mL, group B 200–20,000 IU/mL, and group C >20,000 IU/mL. The rates of postoperative complications, especially the rate of postoperative liver failure, were compared.

Results

There were significant differences among the three groups in the rates of postoperative liver failure. On multivariate logistic regression analysis, a high preoperative HBV DNA level was an independent risk factor for postoperative liver failure.

Conclusions

Preoperative HBV DNA level was a significant risk factor for postoperative hepatic dysfunction.     

Liver-to-Spleen Ratio as an Index of Chronic Liver Diseases and Safety of Hepatectomy: A Pilot Study

Background

Hepatic failure is a main cause of death after hepatectomy. Accurate preoperative evaluation of functional liver reserve is the key to ensure safe resection. Studies have found that the spleen would gradually enlarge as chronic liver disease worsened. This study was designed to determine whether preoperative liver-to-spleen ratio (LSR) would be an indicator to evaluate severity of liver disease and predict safety of hepatectomy.

Methods

The volumes of liver and spleen were evaluated on computed tomography scan in 67 patients who received partial hepatectomy. Preoperative LSR was calculated. Statistical analysis was conducted to examine the relationship between LSR and the degree of chronic liver disease. Ability of LSR to predict the safety of hepatectomy also was evaluated.

Results

LSR had a negative correlation with the degree of chronic liver diseases (r = ?0.606, P < 0.0001). LSR = 3.22 was the cutoff point for predicting posthepatectomy complications and inadequacy. AUC, sensitivity, and specificity for predicting posthepatectomy complications and inadequacy respectively were 0.830 (95 % confidence interval [CI] 0.715–0.950, P < 0.0001), 69.6, 93.2 %, and 0.863 (95 % CI 0.777–0.949, P < 0.0001), 68.8, 84.3 %. Multivariate analysis showed that LSR = 3.22 was the factor that affected both posthepatectomy complications and liver inadequacy.

Conclusions

Preoperative LSR score correlated well with the degree of chronic liver diseases, and it probably help us to improve the safety of hepatectomy.     

Gastric fluid volume in infants for pyloromyotomy

Purpose

To quantify gastric fluid volumes in infants with pylonc stenosis presenting for pyloromyotomy and to demonstrate endoscopically the efficacy of blind aspiration for gastric fluid recovery. We hypothesized that previous diagnostic contrast studies, preoperative nasogastric suction, and fasting interval would not affect these volumes.

Methods

Seventy-five infants scheduled for pyloromyotomy were given atropine before induction of anaesthesia. For those who had undergone preoperative nasogastric suction, the nasogastric tube was aspirated and removed. A 14 F multionficed orogastric catheter was blindly passed to aspirate gastric fluid for measurement. Following tracheal intubation. I 5/75 subjects underwent gastroscopy to measure residual gastric fluid.

Results

Gastric fluid volume removed by blind aspiration averaged 4.8 ± 4.3 ml·kg^?1 with 83% of patients having > 1.25 ml·kg^?1. Although 14 of the 15 patients evaluated by endoscope had ≤ 1 ml residual gastric fluid, one had 1.8 ml·kg^?1. Recovery of total gastric fluid volume by blind aspiration averaged 96 ± 7%. The large gastric fluid volumes were independent of a history of banum study, preoperative nasogastric suction, and fasting interval.

Conclusion

Infants with pylonc stenosis have large gastric fluid volumes which are not substantially reduced by preoperative nasogastric suction. Blind aspiration of gastric contents prior to induction of anaesthesia provides a reliable estimate of total gastric fluid for most of these infants, although the occasional infant may retain a small amount of gastric fluid. The clinical importance of such a residual volume is uncertain.     

Virtual Liver Resection and Volumetric Analysis of the Future Liver Remnant using Open Source Image Processing Software

Background

After extended liver resection, a remnant liver that is too small can lead to postresection liver failure. To reduce this risk, preoperative evaluation of the future liver remnant volume (FLRV) is critical. The open-source OsiriX^® PAC software system can be downloaded for free and used by nonradiologists to calculate liver volume using a stand-alone Apple computer. The purpose of this study was to assess the accuracy of OsiriX^® CT volumetry for predicting liver resection volume and FLVR in patients undergoing partial hepatectomy.

Methods

Preoperative contrast-enhanced liver CT scans of patients who underwent partial hepatectomy were analyzed by three observers. Two surgical trainees measured the total liver volume, resection volume, and tumor volume using OsiriX^®, and a radiologist measured these volumes using CT scanner-linked Aquarius iNtuition^® software. Resection volume was correlated with prospectively determined resection weight, and differences in the measured liver volumes were analyzed. Interobserver variability was assessed using Bland–Altman plots.

Results

25 patients (M/F ratio: 13/12) with a median age of 61 (range, 34–77) years were included. There were significant correlations between the weight and volume of the resected specimens (Pearson’s correlation coefficient: R² = 0.95). There were no major differences in total liver volumes, resection volumes, or tumor volumes for observers 1, 2, and 3. Bland–Altman plots showed a small interobserver variability. The mean time to complete liver volumetry for one patient using OsiriX^® was 19 ± 3 min.

Conclusions

OsiriX^® liver volumetry performed by surgeons is an accurate and time-efficient method for predicting resection volume and FLRV.     

Influence of Preoperative Chemotherapy on CT Volumetric Liver Regeneration Following Right Hemihepatectomy

Background

An increasing number of patients undergo major liver resection following preoperative chemotherapy. Liver regeneration may be impaired in these patients, predisposing them to postoperative liver dysfunction. The aim of the present study was to evaluate the effects of preoperative chemotherapy on liver regeneration after partial liver resection.

Methods

Patients planned to receive right hepatectomy either with (group B) or without (group A) prior chemotherapy were identified retrospectively from a prospective multi-institutional database created in the conduct of a national randomized controlled trial (RCT). Prior chemotherapy was neither an inclusion nor an exclusion criterion of the trial. Future remnant liver volume (FRLV) was calculated by measuring total functional liver volume and resection specimen on preoperative computed tomography (CT) scans. Remnant liver volume after 7 days (V _RLV7days) was measured on scheduled postoperative CT scans. The early regeneration index 7 days after surgery (RI _early) was calculated as [(V _RLV7days ? FRLV) / FRLV] × 100 %. Data are expressed as median (interquartile range).

Results

A total of 72 patients were enrolled: 45 in group A and 27 in group B. For the whole group, the liver remnant showed a 58 % (39 %) increase in volume at day 7 (1) day. The RI _early was not significantly different between groups A and B, 60 % (36 %) and 50 % (43 %), respectively (p = 0.47). The RI _early was significantly lower in patients who had undergone more than six cycles of chemotherapy.

Conclusions

Preoperative chemotherapy does not seem to have a negative impact on early liver regeneration after partial liver resection.     

ALPPS in Right Trisectionectomy: a Safe Procedure to Avoid Postoperative Liver Failure?

Introduction

To induce rapid hepatic hypertrophy and to reduce post-hepatectomy liver failure (PHLF), associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) has been recently developed for patients with a limited future liver remnant. The aim of this study was to further assess the perioperative risk of this procedure and its specific indications.

Patients and Methods

The study was performed between November 2010 and April 2012 for patients undergoing right trisectionectomy by the ALPPS approach. Liver volume, intra- and postoperative complications, including PHLF, and residual tumour status were compared for patients with different diagnoses.

Results

The interval between two operations in nine patients undergoing ALPPS was 13 days (median). Sufficient hepatic hypertrophy was achieved with a volume gain of 87.2 % (median). All patients underwent right trisectionectomy without residual tumours. In contrast to six patients with uneventful intra- and postoperative course, bile leak, vancomycin-resistant enterococcus infection, PHLF and sepsis developed in two of three patients with hilar cholangiocarcinoma as the preoperative diagnosis.

Conclusion

ALPPS leads to sufficient hepatic hypertrophy within 2 weeks, avoiding PHLF in most patients. In patients with hilar cholangiocarcinoma, ALPPS should be applied with extreme caution due to high morbidity and mortality.     

Portal Vein Thrombosis After Hepatectomy

Background

Although various complications after hepatectomy have been reported, there have been no large studies on postoperative portal vein thrombosis (PVT) as a complication. This study evaluated the incidence, risk factors, and clinical outcomes of PVT after hepatectomy.

Methods

The preoperative and postoperative clinical characteristics of patients who underwent hepatectomy were retrospectively analyzed.

Results

A total of 208 patients were reviewed. The incidence of PVT after hepatectomy was 9.1 % (n = 19), including main portal vein (MPV) thrombosis (n = 7) and peripheral portal vein (PPV) thrombosis (n = 12). Patients with MPV thrombosis had a significantly higher incidence of right hepatectomy (p < 0.001), larger resection volume (p = 0.003), and longer operation time (p = 0.021) than patients without PVT (n = 189). Multivariate analysis identified right hepatectomy as a significant independent risk factor for MPV thrombosis (odds ratio 108.9; p < 0.001). Patients with PPV thrombosis had a significantly longer duration of Pringle maneuver than patients without PVT (p = 0.002). Among patients who underwent right hepatectomy, those with PVT (n = 6) had a significantly lower early liver regeneration rate than those without PVT (n = 13; p = 0.040), and those with PVT had deterioration of liver function on postoperative day 7. In all patients with MPV thrombosis who received anticoagulation therapy, PVT subsequently resolved.

Conclusions

Postoperative PVT after hepatectomy is not rare. It is closely related to delayed recovery of liver function and delayed liver regeneration.     

Sinusoidal obstruction syndrome compromises liver regeneration in patients undergoing two-stage hepatectomy with portal vein embolization

Purpose

Several factors have been reported to affect liver regeneration after portal vein embolization (PVE); however, the effect of sinusoidal obstruction syndrome (SOS) has not been evaluated. Therefore, we assessed the effect of SOS on liver regeneration after PVE in patients with multiple bilobar colorectal liver metastases scheduled to undergo two-stage hepatectomy (TSH) combined with PVE.

Methods

The subjects of this study were 78 patients prospectively scheduled to undergo TSH between December 1996 and August 2009. Archived formalin-fixed, paraffin-embedded nontumoral tissue samples were collected from the 1st- and 2nd-stage hepatectomies in 42 and 45 patients, respectively, and SOS and steatohepatitis were diagnosed pathologically. We analyzed the clinicopathological variables affecting liver regeneration after PVE.

Results

Sinusoidal obstruction syndrome was diagnosed in 11 (26.2%) and 20 patients (44.4%) at the time of the 1st- and 2nd-stage hepatectomy, respectively. Patients with SOS at the 1st-stage hepatectomy had a significantly lower hypertrophy ratio of the future remnant liver (FRL) after PVE than patients without SOS (16.8 ± 24.0 vs 55.6 ± 32.5; P < 0.001). Multivariate logistic regression analysis revealed that SOS was an independent factor predicting lower FRL hypertrophy after PVE (??% FRL <20: hazard ratio 31.7, 95% confidence interval 2.84?C355.12; P = 0.005). The incidence of postoperative transient liver failure after the 2nd-stage hepatectomy in patients presenting with SOS was higher than that in those without SOS, but the difference did not reach significance (25.0% vs 4.0%; P = 0.052). Steatohepatitis was confirmed at the 1st- and 2nd-stage hepatectomy in 6 (14.3%) and 3 (6.7%) patients, respectively.

Conclusion

Sinusoidal obstruction syndrome inhibits FRL hypertrophy after PVE and induces postoperative liver failure. Therefore, an alternative strategy is needed to perform TSH safely in the presence of SOS.     

Isolated caudate lobectomy with pancreatoduodenectomy for a bile duct cancer

Background

In patients with distal bile duct cancer involving the hepatic hilus, a major hepatectomy concomitant with pancreatoduodenectomy (HPD) is sometimes ideal to obtain a cancer-free resection margin. However, the surgical invasiveness of HPD is considerable.

Patients and methods

We present our treatment option for patients with distal bile duct cancer showing mucosal spreading to the hepatic hilum associated with impaired liver function. To minimize resection volume of the liver, an isolated caudate lobectomy (CL) with pancreatoduodenectomy (PD) using an anterior liver splitting approach is presented. Liver transection lines and bile duct resection points correspond complete with our standard right and left hemihepatectomies with CL for perihilar cholangiocarcinoma.

Results

Total operation time was 765 min, and pedicle occlusion time was 124 min, respectively. Although the proximal mucosal cancer extension was identified at both the right and the left hepatic ducts, all resection margins were negative for cancer.

Conclusions

Isolated CL with PD is an alternative radical treatment option for bile duct cancer patients with impaired liver function.     

Increased Stiffness of the Remnant Right Lobe Liver After Left Lobectomy or Lateral Segmentectomy in Donors of Living-Donor Liver Transplantation

Background

Liver stiffness is associated with the degree of fibrosis along with other factors. Abrupt change of liver perfusion after hepatectomy is one such factor. In this study, we performed ultrasound elastography to explore the stiffness of the right lobe liver before and after hepatectomy in donors who underwent resection of left lobe or lateral segment of liver.