Three-dimensional computed tomography for planning donor hepatectomy

3-D reconstruction in liver surgery: a systematic review

BACKGROUND

Three-dimensional reconstruction of the liver offers several advantages to the surgeon before and during liver resection. This review discusses the factors behind the use of liver 3-D reconstruction.

METHODS

Systematic electronic search, according to PRISMA criteria, was performed. A literature search of scientific papers was performed until October 2023. Articles were chosen based on reference to 3-D liver reconstruction and their use in liver surgery. GRADE methodology and the modified Newcastle-Ottawa scale were used to assess the quality of the studies.

RESULTS

The research included 47 articles and 7724 patients were analyzed. Preoperative planning was performed with 3-D liver reconstruction in the 87.2% of the studies. Most of preoperative 3-D liver reconstructions were performed in the planning of complex or major hepatectomies. Complex hepatectomies were performed in 64.3% patients. The 55.3% of the studies reported an improved navigation and accuracy during liver resection. Four studies (8.6%) on living donor liver transplant (LDLT) concluded that 3-D liver reconstruction is useful for graft selection and vascular preservation. Nine papers (19.1%) reported an accurate measurement of future liver remnant.

CONCLUSION

Liver 3-D reconstruction helps surgeons in the planning of liver surgery, especially in liver graft and complex liver resections, increasing the accuracy of the surgical resection.

Perceptions of porta-celiac vascular models for hepatic surgery and their use in residency training

BACKGROUND

Primary aspect of hepatic navigation surgery is the identification of source vascular details to preserve healthy liver which has a vascular anatomy quite challenging for the young surgeons. The purpose was to determine whether three-dimensional (3D) vascular pattern models of preoperative computed tomography (CT) images will assist resident-level trainees for hepatic surgery.

METHODS

This study was based on the perception of residents who were presented with 5 different hepatic source vascular patterns and required to compare their perception level of CT, and 1:1 models in terms of importance of variability, differential of patterns and preoperative planning.

RESULTS

All residents agree that models provided better understanding of vascular source and improved preplanning. Five stations provided qualitative assessment with results showing the usefulness of porta-celiac models when used as anatomical tools in preplanning (p = 0.04), simulation of interventional procedures (p = 0.02), surgical education (p = 0.01). None of the cases had scored less than 8.5. Responses related to understanding variations were significantly higher in the perception of the 3D model in all cases, furthermore 3D models were more useful for seniors in more complex cases 3 and 5. Some open-ended answers: "The 3D model can completely change the operation plan" One of the major factors for anatomical resection of liver transplantation is the positional relationship between the hepatic arteries and the portal veins.

CONCLUSION

The plastic-like material presenting the hepatic vascularity enables the visualization of the origin, pattern, shape, and angle of the branches with appropriate spatial perception thus making it well-structured.

Effects of laparoscopy, laparotomy, and respiratory phase on liver volume in a live porcine model for liver resection

Background

Hepatectomy, living donor liver transplantations and other major hepatic interventions rely on precise calculation of the total, remnant and graft liver volume. However, liver volume might differ between the pre- and intraoperative situation. To model liver volume changes and develop and validate such pre- and intraoperative assistance systems, exact information about the influence of lung ventilation and intraoperative surgical state on liver volume is essential.

Methods

This study assessed the effects of respiratory phase, pneumoperitoneum for laparoscopy, and laparotomy on liver volume in a live porcine model. Nine CT scans were conducted per pig (N = 10), each for all possible combinations of the three operative (native, pneumoperitoneum and laparotomy) and respiratory states (expiration, middle inspiration and deep inspiration). Manual segmentations of the liver were generated and converted to a mesh model, and the corresponding liver volumes were calculated.

Results

With pneumoperitoneum the liver volume decreased on average by 13.2% (112.7 ml ± 63.8 ml, p < 0.0001) and after laparotomy by 7.3% (62.0 ml ± 65.7 ml, p = 0.0001) compared to native state. From expiration to middle inspiration the liver volume increased on average by 4.1% (31.1 ml ± 55.8 ml, p = 0.166) and from expiration to deep inspiration by 7.2% (54.7 ml ± 51.8 ml, p = 0.007).

Conclusions

Considerable changes in liver volume change were caused by pneumoperitoneum, laparotomy and respiration. These findings provide knowledge for the refinement of available preoperative simulation and operation planning and help to adjust preoperative imaging parameters to best suit the intraoperative situation.

Validation of Functional Assessment for Liver Resection Considering Venous Occlusive Area after Extended Hepatectomy

BACKGROUND

Previous studies demonstrated that liver function in a veno-occlusive region is approximately 40% of that in a non-veno-occlusive region after hepatectomy with excision of major hepatic vein. We validated the preoperative assessment of future remnant liver (FRL) function based on 40% decreased function of the veno-occlusive region.

METHODS

Sixty patients who underwent hepatectomy with excision of major hepatic vein were analyzed. The FRL functions of the veno-occlusive and non-veno-occlusive regions were calculated with 99mTc-galactosyl human serum albumin scintigraphy single-proton emission computed tomography fusion system and SYNAPSE VINCENT® preoperatively. Risk assessment for hepatectomy was evaluated based on indocyanine green retention at 15 min, and patients with insufficient FRL function were described as marginal.

RESULTS

The median volume and function of the veno-occlusive region per whole liver were 111 ml and 11.0%, respectively. When the function of the veno-occlusive region was presumed as 0%, 40%, and 100%, the FRL function was 62.5%, 68.4%, and 75.0% and 21, 15, and 7 patients were classified as marginal, respectively. When the function of the veno-occlusive region was presumed as 40%, the posthepatectomy liver failure (PHLF) rate of marginal patients was significantly higher than that of safe patients (46.7% vs 8.9%, P = 0.002). Multivariable analysis indicated that marginal FRL function based on 40% decreased function of the veno-occlusive region was the only independent risk factor for PHLF (odds ratio 8.97, P = 0.002) after extended hepatectomy.

CONCLUSION

Assessment of preoperative FRL function based on 40% decreased function of the veno-occlusive region may have high validity.

How Has Virtual Hepatectomy Changed the Practice of Liver Surgery?: Experience of 1194 Virtual Hepatectomy Before Liver Resection and Living Donor Liver Transplantation

OBJECTIVE

To assess how virtual hepatectomy (VH), conducted using surgical planning software, influences the outcomes of liver surgery.

BACKGROUND

Imaging technology visualizes the territories of the liver vessels, which were previously impossible. However, the clinical impact of VH has not been evaluated.

METHODS

From 2004 to 2013, we performed 1194 VHs preoperatively. Outcomes of living donor liver transplantation (LDLT) and hepatectomy for hepatocellular carcinoma (HCC)/colorectal liver metastases (CRLM) were compared between patients in whom VH was performed (VH) and those without VH evaluation (non-VH).

RESULTS

In LDLT, the rate of right liver graft use was higher in the VH (62.1%) than in the non-VH (46.5%) (P < 0.01), which did not increase morbidity of donor surgery. Duration of recipient surgery in the VH in which middle hepatic vein branch reconstruction was skipped was shorter than that in the VH with venous reconstruction. Among HCC patients with impaired liver function, portal territory-oriented resection was conducted more often in the VH than in the non-VH. The 5-year disease-free survival rate for localized HCC was higher in the VH than in the non-VH (37.2% vs 23.9%; P = 0.04). In CRLM, long-term outcomes were similar in the VH and non-VH despite the larger tumor load in the VH.

CONCLUSIONS

VH in LDLT allows double equipoise for the recipient and donor by optimizing decision-making on graft selection and venous reconstruction. VH offers a chance for radical hepatectomy even in HCC patients with impaired liver function and CRLM patients with advanced tumors, without compromising survival.

Anatomical Boundary Between the Caudate Lobe of the Liver and Adjacent Segments Based on Three-Dimensional Analysis for Precise Resections

BACKGROUND

Right hemihepatectomy or systematic resection of segment 7 or 8 involves partial resection of the paracaval portion of the caudate lobe. However, the boundary between the caudate lobe and segment 7 or 8 remains unclear. We examined the anatomical territory of the caudate lobe with special reference to the boundary between the paracaval portion and segment 7 or 8 for precise anatomical hepatectomies.

METHODS

We enrolled 63 consecutive healthy donor candidates for living-donor liver transplantation from 2012 to 2014 in this study. The caudate lobe was defined according to Kumon's subdivision system, and the boundary between the paracaval portion and segment 7 or 8 was investigated based on three-dimensional computed tomography scan images using SYNAPSE VINCENT^®.

RESULTS

The paracaval portion of the liver protruded on the liver surface underneath the right diaphragm on the ventral side of the right hepatic vein (RHV) in 10 participants (16%) and on the dorsal side of the RHV in 9 participants (14%). A branch of the RHV, the "paracaval vein," was found in all 63 participants and ran longitudinally along the right border of the paracaval portion (n = 30, 48%) and within segment 7 (n = 16, 25%) or segment 8 (n = 17, 27%).

CONCLUSIONS

The paracaval portion of the liver protruded on the liver surface underneath the right diaphragm in one third of our participants. The paracaval vein can be a landmark for the boundary between the caudate lobe and the segment 7 or 8 in half of the cases.

Segmentation of liver and vessels from CT images and classification of liver segments for preoperative liver surgical planning in living donor liver transplantation

BACKGROUND AND OBJECTIVE

The present study developed an effective surgical planning method consisting of a liver extraction stage, a vessel extraction stage, and a liver segment classification stage based on abdominal computerized tomography (CT) images.

METHODS

An automatic seed point identification method, customized level set methods, and an automated thresholding method were applied in this study to extraction of the liver, portal vein (PV), and hepatic vein (HV) from CT images. Then, a semi-automatic method was developed to separate PV and HV. Lastly, a local searching method was proposed for identification of PV branches and the nearest neighbor approximation method was applied to classifying liver segments.

RESULTS

Onsite evaluation of liver segmentation provided by the SLIVER07 website showed that the liver segmentation method achieved an average volumetric overlap accuracy of 95.2%. An expert radiologist evaluation of vessel segmentation showed no false positive errors or misconnections between PV and HV in the extracted vessel trees. Clinical evaluation of liver segment classification using 43 CT datasets from two medical centers showed that the proposed method achieved high accuracy in liver graft volumetry (absolute error, AE = 45.2 ± 20.9 ml; percentage of AE, %AE = 6.8% ± 3.2%; percentage of %AE > 10% = 16.3%; percentage of %AE > 20% = none) and the classified segment boundaries agreed with the intraoperative surgical cutting boundaries by visual inspection.

CONCLUSIONS

The method in this study is effective in segmentation of liver and vessels and classification of liver segments and can be applied to preoperative liver surgical planning in living donor liver transplantation.

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.

Liver transection using indocyanine green fluorescence imaging and hepatic vein clamping

BACKGROUND

Three-dimensional (3D) imaging has facilitated liver resection with excision of hepatic veins by estimating the liver volume of portal and hepatic venous territories. However, 3D imaging cannot be used for real-time navigation to determine the liver transection line. This study assessed the value of indocyanine green (ICG) fluorescence imaging with hepatic vein clamping for navigation during liver transection.

METHODS

Consecutive patients who underwent liver resection with excision of major hepatic veins between 2012 and 2013 were evaluated using ICG fluorescence imaging after clamping veins and injecting ICG. Regional fluorescence intensity (FI) values of non-veno-occlusive regions (FI_Non ), veno-occlusive regions (FI_VO ) and ischaemic regions (FI_IS ) were calculated using luminance analysing software.

RESULTS

Of the 21 patients, ten, four and seven underwent limited resection, monosegmentectomy/sectionectomy and hemihepatectomy respectively, with excision of major hepatic veins. Median veno-occlusive liver volume was 80 (range 30-458) ml. Fluorescence imaging visualized veno-occlusive regions as territories with lower FI compared with non-veno-occlusive regions, and ischaemic regions as territories with no fluorescence after intravenous ICG injection. Median FI_IS /FI_Non was lower than median FI_VO /FI_Non (0·22 versus 0·59; P = 0·002). There were no deaths in hospital or within 30 days, and only one major complication.

CONCLUSION

ICG fluorescence imaging with hepatic vein clamping visualized non-veno-occlusive, veno-occlusive and ischaemic regions. This technique may guide liver transection by intraoperative navigation, enhancing the safety and accuracy of liver resection.

Reconstruction of hepatic venous tributary in right liver living donor liver transplantation: The importance of the inferior right hepatic vein

Special care must be taken in hepatic vein reconstruction to avoid outflow block in living donor liver transplantation (LDLT) with a right liver graft. We have used cryopreserved homologous veins to reconstruct the right hepatic vein (RHV), middle hepatic vein (MHV), MHV tributaries (V5 and V8), and inferior right hepatic vein (IRHV). The reconstruction of V5, V8, and IRHV was based on the estimated congestive volume, calculated by the computed tomography volumetry, to secure the functional graft volume of 40% of the recipient standard liver volume. Among 262 right liver LDLT recipients, the number of reconstructed RHVs, MHVs, V5s, V8s, and IRHVs was 262, 48, 110, 111, and 147, respectively, and the overall patency was 95%, 100%, 36%, 58%, and 86%, respectively. Although the patency of the RHVs and MHVs was satisfactory, that of the V5s, V8s, and IRHVs was suboptimal. Patency of the IRHVs (86%, 126/147) was significantly better than that of both V5s (36%, 40/110) and V8s (58%, 64/111; P < 0.001). In addition, the estimated volume drained by IRHVs was significantly greater than that of V5s and V8s (IRHV, 176 ± 92 mL; V5, 105 ± 49 mL; V8, 127 ± 60 mL; P < 0.001). The patency of IRHV was significantly improved by applying the double inferior vena cava method (93%, 94/101) when compared to the direct anastomosis to vena cava (68%, 25/37; P < 0.001). The IRHV functioned as a main drainage route in cases of an obstructed RHV. In conclusion, reconstruction of the IRHV is recommended, not only to improve the functional reserve of the graft, but also to secure multiple drainage routes of the graft.

Advances in Assessment and Planning for Surgical Treatment of Hepatocellular Carcinoma

This chapter covers recent important topics relevant to ensuring safe liver resection. In particular, preoperative and intraoperative techniques, such as 3-dimensional CT, intraoperative ultrasonography with contrast agent and fluorescence imaging using indocyanine green are reportedly useful and have been applied to liver resection and liver transplantation. We, herein, describe the performance of liver resection under the guidance of these techniques and present tips for more accurate intraoperative tumor detection and safer surgical procedures.

Risk of venous congestion in live donors of extended right liver graft

AIM: To investigate middle hepatic vein (MHV) management in adult living donor liver transplantation and safer remnant volumes (RV).

METHODS: There were 59 grafts with and 12 grafts without MHV (including 4 with MHV-5/8 reconstructions). All donors underwent our five-step protocol evaluation containing a preoperative protocol liver biopsy Congestive vs non-congestive RV, remnant-volume-body-weight ratios (RVBWR) and postoperative outcomes were evaluated in 71 right graft living donors. Dominant vs non-dominant MHV anatomy in total liver volume (d-MHV/TLV vs nd-MHV/TLV) was constellated with large/small congestion volumes (CV-index). Small for size (SFS) and non-SFS remnant considerations were based on standard cut-off- RVBWR and RV/TLV. Non-congestive RVBWR was based on non-congestive RV.

RESULTS: MHV and non-MHV remnants showed no significant differences in RV, RV/TLV, RVBWR, total bilirubin, or INR. SFS-remnants with RV/TLV < 30% and non-SFS-remnants with RV/TLV ≥ 30% showed no significant differences either. RV and RVBWR for non-MHV (n = 59) and MHV-containing (n = 12) remnants were 550 ± 95 mL and 0.79 ± 0.1 mL vs 568 ± 97 mL and 0.79 ± 0.13, respectively (P = 0.423 and P = 0.919. Mean left RV/TLV was 35.8% ± 3.9%. Non-MHV (n = 59) and MHV-containing (n = 12) remnants (34.1% ± 3% vs 36% ± 4% respectively, P = 0.148. Eight SFS-remnants with RVBWR < 0.65 had a significantly smaller RV/TLV than 63 non-SFS-remnants with RVBWR ≥ 0.65 [SFS: RV/TLV 32.4% (range: 28%-35.7%) vs non-SFS: RV/TLV 36.2% (range: 26.1%-45.5%), P < 0.009. Six SFS-remnants with RV/TLV < 30% had significantly smaller RVBWR than 65 non-SFS-remnants with RV/TLV ≥ 30% (0.65 (range: 0.6-0.7) vs 0.8 (range: 0.6-1.27), P < 0.01. Two (2.8%) donors developed reversible liver failure. RVBWR and RV/TLV were concordant in 25%-33% of SFS and in 92%-94% of non-SFS remnants. MHV management options including complete MHV vs MHV-4A selective retention were necessary in n = 12 vs n = 2 remnants based on particularly risky congestive and non-congestive volume constellations.

CONCLUSION: MHV procurement should consider individual remnant congestive- and non-congestive volume components and anatomy characteristics, RVBWR-RV/TLV constellation enables the identification of marginally small remnants.

Reappraisal of the inferior right hepatic vein preserving liver resection

BACKGROUND

To resect tumors infiltrating to the right hepatic vein at its root, right hemihepatectomy or that following portal vein embolization (PVE) is applied. If the IRHV is sizable, the IRHV preserving liver resection can be another option.

METHODS

Between 1994 and 2007, the IRHV preserving liver resection was performed in 21 patients (IRHV group). The short-term outcomes after surgery of them p.

RESULTS

There were no mortality and no significant difference between the IRHV and RH groups concerning the blood loss, the morbidity rates and the duration of hospital stay. The median operation time was shorter in the IRHV group than in the RH group (393 vs. 480 min, p = 0.0409). The median weight of resected specimen of the IRHV group was 293 g (range: 20-982), which was significantly lighter than that of the RH group (median: 680 g [250-4,300], p < 0.001). The median percentage of resected volume to standard liver volume was significantly smaller in the IRHV group than in the RH group (25.8 vs. 52.2%, p < 0.001).

CONCLUSION

The IRHV preserving liver resection remains a safe and useful procedure.

Adult right living-donor liver transplantation with special reference to reconstruction of the middle hepatic vein

Two hundred fifty-three consecutive living-donor liver transplant recipients with a right liver graft (RLG) were divided into three groups: an extended right liver graft (ERLG) group (n = 47) in which the middle hepatic vein (MHV) trunk was included in the graft, a modified right liver graft (MRLG) group (n = 114) in which the MHV tributaries were reconstructed with cryopreserved homologous veins and a simple RLG group (n = 92) in which the MHV tributaries were sacrificed. The volume of the anterior sector was significantly impaired in the RLG group compared to the other two groups, whereas the volume of the posterior sector was significantly improved in the RLG group, indicating that the impaired anterior sector regeneration by MHV deprivation was compensated by the posterior sector regeneration. The regeneration rate of the anterior sector was highest in the ERLG group (92%), moderate in the MRLG group (71%) and lowest in the RLG group (52%). The whole graft regeneration rate of the ERLG group was significantly higher than that of the other two groups. Poor regeneration, however, was not correlated with delayed functional recovery or long-term outcome. Short-term, the patency of reconstructed MHV tributaries was over 90%, but occlusion occurred frequently over the long-term, especially in V5.

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.

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.

Three-dimensional print of a liver for preoperative planning in living donor liver transplantation

The growing demand for liver transplantation and the concomitant scarcity of cadaveric livers have increased the need for living donor liver transplantation (LDLT). Ensuring the safety of donors and recipients is critical. The preoperative identification of the vascular and biliary tract anatomy with 3-dimensional (3D) printing may allow better preoperative surgical planning, avert unnecessary surgery in patients with potentially unsuitable anatomy, and thereby decrease the complications of liver transplant surgery. We developed a protocol and successfully 3D-printed synthetic livers (along with their complex networks of vascular and biliary structures) replicating the native livers of 6 patients: 3 living donors and 3 respective recipients who underwent LDLT. To our knowledge, these are the first complete 3D-printed livers. Using standardized preoperative, intraoperative, and postoperative assessments, we demonstrated identical anatomical and geometrical landmarks in the 3D-printed models and native livers.

Utility of augmented reality system in hepatobiliary surgery

BACKGROUND/PURPOSE

The aim of this study was to evaluate the utility of an image display system for augmented reality in hepatobiliary surgery under laparotomy.

METHODS

An overlay display of organs, vessels, or tumor was obtained using a video see-through system as a display system developed at our institute. Registration between visceral organs and the surface-rendering image reconstructed by preoperative computed tomography (CT) was carried out with an optical location sensor. Using this system, we performed laparotomy for a patient with benign biliary stricture, a patient with gallbladder carcinoma, and a patient with hepatocellular carcinoma.

RESULTS

The operative procedures performed consisted of choledochojejunostomy, right hepatectomy, and microwave coagulation therapy. All the operations were carried out safely using images of the site of tumor, preserved organs, and resection aspect overlaid onto the operation field images observed on the monitors. The position of each organ in the overlaid image closely corresponded with that of the actual organ. Intraoperative information generated from this system provided us with useful navigation. However, several problems such as registration error and lack of depth knowledge were noted.

CONCLUSION

The image display system appeared to be useful in performing hepatobiliary surgery under laparotomy. Further improvement of the system with individualized function for each operation will be essential, with feedback from clinical trials in the future.

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.

AUTOMATIC MULTI-SCALE SEGMENTATION OF INTRAHEPATIC VESSEL IN CT IMAGES FOR LIVER SURGERY PLANNING

The processing of blood vessels is an indispensable part in complicated surgeries of livers and hearts as the development of medical image technologies, which requires an automatic segmentation system over CT images of organs. However, the vascular pattern of livers in CT images suffers from low contrast to background so that the existing segmentation technologies are not able to extract the blood vessels completely. In the paper, we propose a new algorithm to extract the blood vessels of livers based on the adaptive multi-scale segmentation. First, we prove that the background histogram of normal scale blood vessels obeys the Gaussian distribution in CT images, and obtain the vascular distribution function from the vascular signal segmented from the background with a local optimal threshold. Second, Hessian matrix is employed to enhance the thin blood vessels before the extraction, and a complete and clear segmentation system for blood vessels is constructed by combining the major and thin blood vessels via filtering. Experimental results show the effectiveness of the proposed method, which is able to extract more complete blood vessels for 3D system, and assist the clinical liver surgeries efficiently.

Portal uptake function in veno-occlusive regions evaluated by real-time fluorescent imaging using indocyanine green

BACKGROUND & AIMS

Although recent advances in preoperative imaging have enabled accurate estimation of the regional liver volume with venous occlusion, the extent of functional decrease in such regions remains unclear. In this study, the portal uptake function in postoperative veno-occlusive regions and non-veno-occlusive regions was evaluated by intraoperative fluorescent imaging after intravenous injection of indocyanine green (ICG).

METHODS

In 22 liver resection patients and 23 recipients and 18 donors of liver transplantation, fluorescent intensity on the remnant liver or the liver graft was evaluated in real time following intravenous injection of ICG (0.0025 mg per 1 ml of remnant liver volume).

RESULTS

Plateau ICG concentrations were significantly lower in the veno-occlusive regions (C(VO)) than in the non-veno-occlusive regions (C(Non)) in liver resection patients (median [range], 0.75 [0.29-2.0]μg/ml vs. 3.0 [0.46-6.4]μg/ml, p<0.001), donors (0.69 [0.29-1.9]μg/ml vs. 2.4 [0.46-6.4]μg/ml, p<0.001), and recipients (0.75 [0.34-1.8]μg/ml vs. 1.8 [0.54-6.4]μg/ml, p<0.001). Distributions of the C(VO)/C(Non) and the ratio of the hepatic uptake rate constant in the veno-occlusive regions to that in non-veno-occlusive regions were both around 40% (mean ± standard deviation, 0.36 ± 0.17 and 0.42 ± 0.16, respectively). When the functional remnant liver volume was calculated as a sum of non-veno-occlusive regions and veno-occlusive regions multiplied by C(VO)/C(Non), its ratio to the total liver volume was correlated with the improved postoperative/preoperative ratio of prothrombin time.

CONCLUSIONS

Portal uptake function in veno-occlusive regions is approximately 40% of that in non-veno-occlusive regions. Intraoperative ICG-fluorescent imaging enables real-time evaluation of the extent of the functional decrease in veno-occlusive regions, enhancing accurate estimation of the hepatic functional reserve for determining the surgical indications and procedures.

The "carving" liver partitioning technique for graft hepatectomy in live donor liver transplantation: a single-center experience

BACKGROUND

In adult live donor liver transplantation, postoperative venous congestion of graft and remnant livers can lead to life-threatening complications. The purpose of this study was to evaluate the safety and benefits of our 3-dimensional, computed tomographic, computer-assisted donor hepatectomy using the "carving" partitioning technique.

METHODS

Eighty-three consecutive adult live donor liver transplantations were performed based on data obtained from individualized preoperative 3-dimensional, computed tomographic reconstructions and virtual graft hepatectomies.

RESULTS

There were 71 right and 12 left grafts. Small grafts (graft volume body weight ratio, <1.0) were used in 20 cases. We observed no clinically important differences in postoperative function between right and left grafts. Four recipients developed lethal small-for-size syndrome. Reversible small-for-size syndrome was observed in a right graft recipient and in 2 right graft donors.

CONCLUSION

Preoperative 3-dimensional, computed tomographic, computer-assisted planning using virtual liver partitioning allowed for: (1) an individualized carving technique based on specific donor anatomic characteristics, (2) donor safety based on individualized patterns of venous outflow, and (3) optimized drainage of the medial area of the graft based on the preferential inclusion of the middle hepatic vein.

Venous reconstruction based on virtual liver resection to avoid congestion in the liver remnant

BACKGROUND

Hepatic vein (HV) reconstruction may prevent venous congestion following resection of liver tumours that encroach on major HVs. This study aimed to identify criteria for venous reconstruction based on preoperative evaluation of venous congestion.

METHODS

A volumetric analysis using image-processing software was performed in selected patients with liver tumours suspected on preoperative imaging of major HV invasion. The size of the non-congested liver remnant (NCLR) was calculated by subtracting the congested area from the liver remnant. Venous reconstruction was scheduled in patients who met the following criteria: normal liver function (indocyanine green retention rate at 15 min (ICGR(15) ) of less than 10 per cent) with a NCLR smaller than 40 per cent of total liver volume (TLV), or liver dysfunction (ICGR(15) 10-20 per cent) with a NCLR smaller than 50 per cent of TLV. Surgical outcomes and liver regeneration were investigated.

RESULTS

A total of 55 patients with suspected HV invasion were enrolled. Sacrifice of one or more HVs was deemed possible in 37 patients. Venous reconstruction was scheduled in 18 patients. At operation, there was seen to be no venous involvement in 11 patients. The HV was sacrificed in 29 patients, and preserved or reconstructed in 24. Volume restoration ratios at 3 months were similar in the sacrifice (88 per cent) and preserve (87 per cent) groups. Operating time was shorter (465 min) and blood loss was lower (580 ml) in the sacrifice than in the preserve group (523 min and 815 ml respectively).

CONCLUSION

The HV can be sacrificed safely according to the proposed criteria, reducing surgical invasiveness without influencing the postoperative course.

Donor quality of life after living donor liver transplantation: a prospective study

BACKGROUND/PURPOSE

It is important to determine the health-related quality of life of live donors in liver transplantation.

MATERIALS AND METHODS

We reviewed 35 live liver donors and prospectively and longitudinally evaluated their health-related quality for 1.5 years post-surgery based on the Short Form-36 version 2 questionnaire. Scores of the donors stratified by the clinical data were analyzed. The study was approved by the University of Tokyo Institutional Review Board (No. 1533).

RESULTS

There was no donor mortality in the donor population studied. The percentage of major complications greater than Clavien's classification grade III was 8.6%. The physical component summary score decreased to 42.9 (p < 0.01) at 3 months, but recovered within 6 months after the operation. The mental component summary scores did not change during the observation period. The stratification study revealed that age and postoperative complications remained significant factors among the high physical component summary scores 3 months after the operation.

CONCLUSIONS

The findings from this survey suggest that liver harvesting does not decrease the donor's quality of life during the 1.5 years following the surgery.

Embolization of hepatic arterial branches to simplify hepatic blood flow before yttrium 90 radioembolization: a useful technique in the presence of challenging anatomy

PURPOSE

In the presence of variant hepatic arterial anatomy, obtaining whole-liver coverage with yttrium 90 (Y90) radioembolization may be challenging. The purpose of this study was to determine whether a technique whereby variant hepatic arterial branches are embolized and then Y90 is administered selectively into one remaining hepatic arterial branch results in whole-liver coverage and effective therapy. A retrospective comparison of treatment response was made between a group of patients who underwent this technique before Y90 administration and a group of patients who received standard Y90 administration as a single dose into the proper hepatic artery or in divided doses into the immediate hepatic artery branches. The rest of the workup and treatment were identical in both groups, including routine embolization of potential nonhepatic, nontarget vessels (e.g., the gastroduodenal artery).

METHODS

A total of 32 patients (mean age 56.9 years, range 39-77 years) treated with Y90 between June 2004 and March 2008 were analyzed. The primary malignancy was colorectal in 29, breast in 2, and cholangiocarcinoma in 1. Group 1 comprised 20 patients who had no alterations to their hepatic arterial supply. Group 2 comprised 12 cases who had undergone prior embolization of hepatic arterial branches before administration of Y90. The response to treatment was assessed by comparing standardized uptake value (SUV) on the pre- and postprocedure fludeoxyglucose positron emission tomographic studies of representative lesions within the right and left lobes of the liver.

RESULTS

In group 1, significant response (P < 0.001) was seen among right lobe lesions but not among left lobe lesions (P = 0.549). In group 2, there was a significant response among both right (P = 0.028) and left (P = 0.014) lobe lesions. No difference was found in the response of right lobe lesions (P = 0.726) between groups 1 and 2; a significantly greater response was found in group 2 compared to group 1 (P = 0.004) for left lobe lesions.

CONCLUSION

Selective Y90 radioembolization after manipulation of hepatic arterial blood supply leads to an even distribution within the entire liver. When variations in hepatic arterial anatomy exist, this technique allows effective whole-liver radioembolization therapy from a single selective arterial injection.

Surgical technique: new advances for expanding indications and increasing safety in liver resection for HCC: the Eastern perspective

PURPOSE

We introduce recent advances in surgical techniques and perioperative management in liver resection for hepatocellular carcinoma (HCC).

METHODS

Our approaches to further enhancing the efficacy of resection for HCC, based on our presentation at "The 6th International Meeting of Hepatocellular Carcinoma: Eastern and Western Experiences" held in Seoul in December 2008, are presented, along with a review of recent advances in this field reported from eastern Asia.

RESULTS

In our series, liver resection enabled a 5-year overall survival rate of close to 60%, even among patients with multiple HCCs and those with portal hypertension in a background of Child-Pugh class A cirrhosis. Favorable long-term results were obtained by the precise evaluation of liver function using the indocyanine green (ICG) test and the application of perioperative treatments for gastroesophageal varices and severe thrombocytopenia. Furthermore, promising novel techniques have been applied to increase the efficacy of HCC resection, including the preoperative simulation of liver resection, using three-dimensional computed tomography, a "peeling-off" technique for resecting HCC with macroscopic portal venous tumor thrombus, ICG-fluorescent imaging, predeposit autologous plasma transfusion, and laparoscopic liver resection.

CONCLUSIONS

The safety and accuracy of liver resection for HCC has been continuously enhanced by advances in surgical techniques and perioperative care. Given that the resection of HCC offers a satisfactory overall survival rate for patients with portal hypertension and those with oligonodular multiple tumors, the surgical indications can now be expanded to include such second-best candidates.

Imaging evaluation of the liver using multi-detector row computed tomography in micropigs as potential living liver donors

The shortage of organ donors has stimulated interest in the possibility of using animal organs for transplantation into humans. In addition, pigs are now considered to be the most likely source animals for human xenotransplantation because of their advantages over non-human primates. However, the appropriate standard values for estimations of the liver of micropigs have not been established. The determination of standard values for the micropig liver using multi-detector row computed tomography (MDCT) would help to select a suitable donor for an individual patient, determine the condition of the liver of the micropigs and help predict patient prognosis. Therefore, we determined the standard values for the livers of micropigs using MDCT. The liver parenchyma showed homogenous enhancement and had no space-occupying lesions. The total and right lobe volumes of the liver were 698.57 ± 47.81 ml and 420.14 ± 26.70 ml, which are 51.74% and 49.35% of the human liver volume, respectively. In micropigs, the percentage of liver volume to body weight was approximately 2.05%. The diameters of the common hepatic artery and proper hepatic artery were 6.24 ± 0.20 mm and 4.68 ± 0.13 mm, respectively. The hepatic vascular system of the micropigs was similar to that of humans, except for the variation in the length of the proper hepatic artery. In addition, the diameter of the portal vein was 11.27 ± 0.38 mm. In conclusion, imaging evaluation using the MDCT was a reliable method for liver evaluation and its vascular anatomy for xenotransplantation using micropigs.

Assessment of liver function for safe hepatic resection

The preoperative assessment of liver function is extremely important for preventing postoperative liver failure and mortality after hepatic resection. Liver function tests may be divided into three types; conventional liver function tests, general scores, and quantitative liver function tests. General scores are based on selected clinical symptoms and conventional test results. Child-Turcotte-Pugh score has been the gold standard for four decades, but the Child-Turcotte-Pugh score has difficulty discriminating a good risk from a poor risk in patients with mild to moderate liver dysfunction. The model for end-stage liver disease score has also been applied to predict short-term outcome after hepatectomy, but it is only useful in patients with advanced cirrhosis. Quantitative liver function tests overcome the drawbacks of general scores. The indocyanine green retention rate at 15 minutes (ICG R15) has been reported to be a significant predictor of postoperative liver failure and mortality. The safety limit of the hepatic parenchymal resection rate can be estimated using the ICG R15, and a decision tree (known as the Makuuchi criteria) for selecting patients and hepatectomy procedures has been proposed. Hepatic resection can be performed with a mortality rate of nearly zero using this decision tree. If the future remnant liver volume does not fulfill the Makuuchi criteria, preoperative portal vein embolization should be performed to prevent postoperative liver failure. Galactosyl human serum albumin-diethylenetriamine-pentaacetic acid scintigraphy also provides data that complement the ICG test. Other quantitative liver function tests, however, require further validation and simplification.

Living donor liver transplantation for fulminant hepatic failure

AIM

The aim of this study was to investigate the safety of living donor liver transplantation (LDLT) for fulminant hepatic failure (FHF) patients.

METHODS

We reviewed the clinical indications, operative procedures and prognosis of LDLT performed on patients with FHF at the University of Tokyo. From January 1996 to August 2007, 96 patients were referred to our department due to severe acute hepatitis or FHF. Of these, 36 underwent LDLT and were the subjects of this study. Of the 36 patients who underwent LDLT, 32 were over 18 years old. The etiologies of FHF included non-A, non-B hepatitis in 23, hepatitis B virus in 11, Wilson's disease in one, and auto-immune hepatitis in one. Graft type included right liver in 18, left liver in 16 and right paramedian sector in two.

RESULTS

Patient and graft survival rates at 5 years were 87% and 82%, respectively. Twenty-three patients had postoperative complications: acute cellular rejection in 12, biliary stricture in eight, bile leakage in six, peritoneal hemorrhage in six and hepatic arterial thrombosis in four.

CONCLUSION

The LDLT procedure provided satisfactory survival rates for FHF patients.