Intrahepatic biliary anatomy derived from right graft adult live donor liver transplantation

OBJECTIVE

The successful management of the bile duct in right graft adult live donor liver transplantation requires knowledge of both its central (hilar) and distal (sectorial) anatomy. The purpose of this study was to provide a systematic classification of its branching patterns to enhance clinical decision-making.

PATIENTS AND METHODS

We analyzed three-dimensional computed tomography (3-D CT) imaging reconstructions of 139 potential live liver donors evaluated at our institution between January 2003 and June 2007.

RESULTS

Fifty-four (n = 54 or 38.8%) donor candidates had a normal (classic) hilar and sectorial right bile duct anatomy (type I). Seventy-eight (n = 78 or 56.1%) cases had either hilar or sectorial branching abnormalities (types II or III). Seven (n = 7 or 5.1%) livers had a mixed type (IV) of a rare and complex central and distal anatomy.

CONCLUSIONS

We believe that the classification proposed herein can aid in the better organization and categorization of the variants encountered within the right-sided intrahepatic biliary system.

Median liver lobe of woodchuck as a model to study hepatic outflow obstruction: a pilot study

BACKGROUND

Hepatic vein outflow obstruction represents an important clinical problem in living-liver transplantation. An animal model is required to study the influence of outflow obstruction on the intrahepatic regulation of liver perfusion and the subsequent effects on liver injury and recovery during liver regeneration. The size of woodchucks enables the use of standard clinical imaging procedures.

AIM

This study aims at describing hepatic vascular and territorial anatomy of the woodchuck liver based on a virtual three-dimensional (3D) visualization of the hepatic vascular tree.

METHODS

Woodchucks (n=6) were subjected to an all-in-one computed tomography (CT) after contrasting the vascular and the biliary tree. CT-images were used for 3D-reconstruction of hepatic and portal veins and calculation of the corresponding portal and hepatic vein territories and their respective volume using hepavision (MeVisLab). A virtual resection was performed following the Cantlie-line and territories at risk were calculated.

RESULTS

The median lobe of the woodchuck liver has a similar vascular supply and drainage as the human liver with two portal (right and left median portal vein) and three hepatic veins (left, middle and right median hepatic vein). The corresponding portal and hepatic vein subterritories are of a similar relative size compared with the human liver. Virtual splitting of the median lobe of the woodchuck liver revealed areas at risk of focal outflow obstruction, as observed clinically.

CONCLUSION

The median liver lobe of the woodchuck represents, to a small extent, the hepatic vascular anatomy of the human liver and is therefore a suitable potential model to correlate repeated imaging of impaired liver perfusion with histomorphological findings of liver damage and regeneration.

ICOS-Dependent and -independent functions of memory CD4 T cells in allograft rejection

Donor-reactive memory T cells undermine the survival of transplanted organs through multiple pathways. We have previously reported that memory CD4 T cells resist treatment with anti-CD154 antibody and donor-specific transfusion (DST/MR1) and promote cardiac allograft rejection via generation of effector CD4 T cells and alloantibody. We hypothesized that the helper functions of memory CD4 T cells are independent of T-cell costimulation through CD154 but instead are regulated by alternative costimulatory pathways. This study investigated how blocking ICOS/B7RP-1 interactions affects functions of donor-reactive memory CD4 T cells. Treatment with blocking anti-ICOS mAb synergized with DST/MR1 and prolonged mouse cardiac allograft survival despite the presence of donor-reactive memory CD4 T cells. While blocking ICOS did not diminish the expansion of preexisting memory CD4 T cells or the induction of allospecific effector T cells, it did inhibit recruitment of the activated memory and effector T cells into the graft. In addition, anti-ICOS mAb treatment in combination with DST/MR1 prevented help provided by memory CD4 T cells for production of donor-specific IgG antibody. These results demonstrate the potential efficacy of ICOS blockade in sensitized transplant patients and provide the foundation for rational use of ICOS blockade in combination with other graft-prolonging strategies.

Virtuelle hepatobiliäre Chirurgie - computerunterstützte Resektionsplanung an der dreidimensional rekonstruierten Leber

Recent developments in image-based computer assistance provide an improved visualisation of the intrahepatic vascular branching system in a virtual three-dimensional model of the liver, allowing a quantitative assessment of any vascular territory. The advantages of computer-assisted resection planning refer to a better preoperative assessment of functional resectability in areas at risk for either devascularisation or impaired drainage. In selected cases, this information may have a considerable influence on operative planning, especially with regard to the extent of resection or the need for vascular reconstruction. Due to the great anatomical variability of the intrahepatic branching patterns of the right liver lobe, this seems to be particularly important in extended left hepatectomies or in repeat hepatectomy when intrahepatic vascular anatomy may be altered. The development of navigation techniques to ensure the accurate application of the preoperative planned resection line is under investigation but not available yet.

Preoperative volume prediction in adult living donor liver transplantation: how much can we rely on it?

Accurate preoperative prediction of functional donor and remnant hemiliver volumes in live donor liver transplantation is essential in preventing postoperative liver failure and optimizing safety. Our aim was (1) to evaluate volume variability associated with multiphasic CT imaging and (2) to determine over- or under-estimations of 3-D CT graft-volume assessments based on 'largest' versus 'smallest' CT phases with respect to intraoperative findings. Native, arterial and venous phase CT images from 83 potential live liver donors were subject to 3-D CT liver volume calculations and virtual 3-D liver partitioning. Estimates were compared to intraoperative volumes obtained in 43 cases. Calculated (preoperative) graft-volume-body-weight-ratios (GVBWR) versus measured (intraoperative) graft-weight-body-weight-ratios (GWBWR) were analyzed. Significant differences in total liver volume- and in graft-liver volume calculations were found among the largest (venous) and smallest (native) CT phases. High significant overestimations were observed in graft-volume determinations and in GVBWR-calculations based on the 'largest' CT phase when compared to intraoperatively obtained graft-weight and -GWBWR values. In contrast, differences among intraoperative measurements and preoperative calculations based on the 'smallest' CT phase yielded less significant overestimations. While 3-D CT volumetry based on the 'largest' (venous) CT phase is associated with considerable overestimation, 3-D volumetry based on the 'smallest' (native) CT phase accurately matches the intraoperative findings.

Preoperative volume prediction in adult living donor liver transplantation: how much can we rely on it?

Accurate preoperative prediction of functional donor and remnant hemiliver volumes in live donor liver transplantation is essential in preventing postoperative liver failure and optimizing safety. Our aim was (1) to evaluate volume variability associated with multiphasic CT imaging and (2) to determine over- or under-estimations of 3-D CT graft-volume assessments based on 'largest' versus 'smallest' CT phases with respect to intraoperative findings. Native, arterial and venous phase CT images from 83 potential live liver donors were subject to 3-D CT liver volume calculations and virtual 3-D liver partitioning. Estimates were compared to intraoperative volumes obtained in 43 cases. Calculated (preoperative) graft-volume-body-weight-ratios (GVBWR) versus measured (intraoperative) graft-weight-body-weight-ratios (GWBWR) were analyzed. Significant differences in total liver volume- and in graft-liver volume calculations were found among the largest (venous) and smallest (native) CT phases. High significant overestimations were observed in graft-volume determinations and in GVBWR-calculations based on the 'largest' CT phase when compared to intraoperatively obtained graft-weight and -GWBWR values. In contrast, differences among intraoperative measurements and preoperative calculations based on the 'smallest' CT phase yielded less significant overestimations. While 3-D CT volumetry based on the 'largest' (venous) CT phase is associated with considerable overestimation, 3-D volumetry based on the 'smallest' (native) CT phase accurately matches the intraoperative findings.

The "territorial belonging" of the middle hepatic vein: a troublesome dilemma in adult live donor liver transplantation--anatomical evidence based on virtual 3-dimensional-computed tomography-imaging reconstructions

BACKGROUND

The venous drainage of the liver plays an essential role in securing viability of both graft and remnant in live donor liver transplantation (LDLT). There is still controversy on whether the middle hepatic vein (MHV) should be routinely included as part of the graft or retained with the remnant liver. The purpose of this study was to analyze hepatic venous drainage patterns based on information obtained by 3-dimensional CT-imaging reconstructions.

METHODOLOGY

Fifty five potential live liver donors were evaluated between January 2003 and May 2004 at our Institution. We analyzed two anatomical definitions of liver dominance: total liver dominance (TLD) and hemiliver dominance (HLD). The following concepts were addressed: 1) Hepatic vein territories, 2) Hepatic vein dominance relationship, 3) Territorial belonging- patterns of the MHV to the right and left hemilivers, additionally an analysis of venous outflow in the central liver sectors was performed.

RESULTS

Our results showed that: 1) The definitions of dominance: TLD vs. HLD overlap, displaying the MHV belonging, by taking into account the individual right hepatic vein (RHV) variability; 2) A dominant RHV for the whole liver indicates that the RHV is also dominant in the right hemiliver; 3) The MHV belongs predominantly to the left hemiliver (LHL); 4) The left hepatic vein (LHV) is dominant in the LHL.

CONCLUSION

Both dominance definitions provide independent mappings of the liver and offer helpful insight into venous dominance relationship.

Computer-gestützte Operationsplanung bei Leberlebendspenden

INTRODUCTION

The appropriate recipient/donor match is a prerequisite for successful living donor liver transplantation (LDLT). A precise knowledge of the liver anatomy and the functional liver volume plays a key role in allocating live liver donor candidates. With the new software HepaVision, we obtained information on liver mapping by means of virtual 3-dimensional non-invasive imaging reconstructions and were able to perform a virtual simulation of the liver transsection. Aim of our study was to investigate, whether this new computer technology is advantageous in surgery planning for LDLT.

METHODS

From January 2002 until December 2004 355 liver transplantations were performed in our department, of which 36 were LDLT. According to our evaluation protocol 135 potential donors (63 male, 72 female) between 18 to 59 years received preoperatively an all-in-one CT. The acquired data sets were further analysed with the software HepaVision (MeVis, Germany).

RESULTS

Of the 135 evaluated donors, we excluded 99 (73 %) from donation based on the HepaVision-data. Reason for exclusion was an inadequate liver volume (70.8 %) or a risk related anatomical anomaly (2.2 %). In the remaining 36 cases a successful graft donation was possible. There were no postoperative complications in the donors and recipients, directly related to a misjudgment of the anatomy or miscalculation of the liver volume.

CONCLUSION

The systematic use of HepaVision for surgery planning proved to be indispensable for proper donor selection. A virtual simulation of the liver transsection on 3D-model additionally increased the safety of the operation, consequently decreasing the risk for the donor.

Anatomical and physiological classification of hepatic vein dominance applied to liver transplantation

BACKGROUND

Proper outflow reconstruction is essential in LDLT. Preoperative planning requires meticulous attention to hepatic vein dominance patterns. The purpose of our study was to provide a combined anatomical-physiological classification of hepatic vein dominance useful for surgical decision-making in both donors and recipients.

METHODOLOGY

We analyzed 3-dimensional CT-imaging reconstructions of 55 potential live liver donors evaluated at our Institution between January 2003 and May 2004.

RESULTS

Our data revealed that: 1) The middle hepatic vein (MHV) and left hepatic vein (LHV) show a relative lack of anatomical diversity, whereas the right hepatic vein (RHV) exhibits multiple variants, 2) 45% donors had inferior hepatic veins (IHV) with anatomically and physiologically relevant venous drainage territories, 3) The RHV is usually dominant when present as a single vein without anatomical IHV (type 1A), or when considered as a complex with IHV (type 1Bx) (80% vs. 88%), 4) Only 55% of dominant type 1Bx RHV/IHV-complex automatically included a dominant type 1By RHV by itself, 5) A single RHV out of anatomical complex with IHV (type 1By) was dominant in only 48% of our donor candidates, 6) The MHV types 2A and 2By are strongly dominant accounting for up to 57% of total liver volume (TLV).

CONCLUSIONS

We propose a new classification based on both anatomical and physiological hepatic venous configurations. Our model also provides a new nomenclature that can be universally applied to preoperative planning in LDLT.

Electrochemical characterisation of dental alloys: its possibilities and limitations

Dental alloys are metallic biomaterials which have a broad variation of composition compared to technical alloys. It is therefore in the interest of patients and technicians to conduct a good assessment of the electrochemical behaviour of dental alloys in order to collect information about their corrosion resistance. The purpose of this work was to demonstrate possibilities and limitations of two electrochemical techniques: the voltammetry of immobilised microparticles (ViMP) onto lead, and cyclic voltammetry measurements with the help of the mini-cell system (MCS). Based on fingerprints obtained from ViMP it was possible to analyse and differentiate the dental alloys. The results obtained by MCS were comparable with ViMP, but give a better understanding of the corrosion behaviour of the materials.

[Evaluation of a new software tool for the automatic volume calculation of hepatic tumors. First results]

PURPOSE

Computed tomography has become the preferred method in detecting liver carcinomas. The introduction of spiral CT added volumetric assessment of intrahepatic tumors, which was unattainable in the clinical routine with incremental CT due to complex planimetric revisions and excessive computing time. In an ongoing clinical study, a new software tool was tested for the automatic detection of tumor volume and the time needed for this procedure.

MATERIALS AND METHODS

We analyzed patients suffering from hepatocellular carcinoma (HCC). All patients underwent treatment with repeated transcatheter chemoembolization of the hepatic arteria. The volumes of the HCC lesions detected in CT were measured with the new software tool in HepaVison (MeVis, Germany). The results were compared with manual planimetric calculation of the volume performed by three independent radiologists.

RESULTS

Our first results in 16 patients show a correlation between the automatically and the manually calculated volumes (up to a difference of 2 ml) of 96.8 %. While the manual method of analyzing the volume of a lesion requires 2.5 minutes on average, the automatic method merely requires about 30 seconds of user interaction time.

CONCLUSION

These preliminary results show a good correlation between automatic and manual calculations of the tumor volume. The new software tool requires less time for accurate determination of the tumor volume and can be applied in the daily clinical routine.