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

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

Angiomixoma agresivo en hombres: Reporte de caso clínico y revisión de la literatura / Aggressive angiomyxoma in men: Clinical case report and literature review

Se presenta el caso clínico de un angiomixoma agresivo, de presentación en un paciente de sexo masculino, con localización presacra, el cual fue diagnosticado e intervenido en el Hospital Militar Central de Bogotá. Se realizó un abordaje tipo Kraske con la escisión completa de la lesión y mínimo impacto funcional y estético para el paciente. Esta clase de tumores son extremadamente infrecuentes y predominan en mujeres, con una localización pélvica. La presentación en hombres es aún más exótica, con pocos casos reportados en la literatura. Su manejo obliga a la extirpación completa de la lesión y al seguimiento clínico e imagenológico periódico, dada su alta tasa de recidiva.

We report a case of a male patient with an aggressive angiomyxoma located in the presacral space which was diagnosed and clinically treated at the Hospital Militar Central in Bogotá, Colombia. Kraske’s posterior approach was used to completely excise the lesion with minimal functional and aesthetic impact on the patient. Aggressive angiomyxomas are extremely rare. They are most commonly found in pelvic locations in women. They are even more exotic in men, with very few cases reported in the literature. Management requires complete removal of the lesion and the clinical and imaging follow-up given their high rate of recurrence.

Computer-assisted surgery planning for complex liver resections: when is it helpful? A single-center experience over an 8-year period.

OBJECTIVE: The purpose of this study was (1) to compare 2-dimensional computed tomographic (2D-CT) and 3D-CT computer-assisted preoperative surgical planning, and (2) to define the indications for the latter method. BACKGROUND: The determination of functional residual liver volumes and the imaging of intrahepatic anatomy are critical when planning complex liver resections. PATIENTS AND METHODS: Prospective study of 202 consecutive patients who underwent high-risk procedures (extended right/left hepatectomies, central resections, polysegmentectomies, large atypical resections, repeated resections, and hepatectomies in the setting of abnormal liver parenchyma). Preoperative evaluation included 3D-CT computer-assisted surgical planning (3D-CASP) and conventional 2D-CT imaging. Endpoints of the study were (1) determination of resectability and (2) changes in operative strategy (resection modifications/extensions/intrahepatic vascular reconstructions). RESULTS: Thirty-four of 202 cases were considered nonresectable on the basis of both 2D and 3D imaging results. In 56 (33%) instances, 3D-CASP either changed the 2D strategy (expansion of resection, n = 40; intrahepatic vascular reconstructions, n = 13) or provided an entirely different approach (n = 3). Eleven (5.4%) cases were considered unresectable at laparotomy on the basis of poor liver quality (n = 8) or unfeasible vascular reconstructions resulting in remnants too small to sustain physiologic function (n = 3). Significant differences between resectional 2D and functional 3D remnant liver volumes were observed in extended left hepatectomies and left trisectionectomies. CONCLUSIONS: 3D-CASP was particularly helpful in patients with unconventional resection planes and in those with central left tumors. Its main advantages were the individualized inflow/outflow virtual analyses and the accurate determination of safely perfused/drained retained liver volumes.

Impact of virtual imaging procedures on treatment strategies in children with hepatic vascular malformations.

OBJECTIVES: Virtual imaging procedures have only rarely been analyzed in pediatric populations. We evaluated the role of CT-based virtual surgery planning in pediatric patients experiencing hepatic vascular malformations (HVM). METHODS: We analyzed 12 children with complex hepatic vascular malformations. All of the children received multislice CT scans with contrast medium followed by virtual 3-dimensional reconstructions using the software assistants MeVis LiverAnalyzer and MeVis LiverExplorer. The impact on treatment planning and the correspondence to clinical findings was assessed. RESULTS: Highest accuracies of virtual data were found in cases of intrahepatic portocaval shunt and persistent ductus venosus. Here, virtual data revealed congenital vascular conditions, which were not always seen using standard imaging diagnostics. In some patients with portalvenous thrombosis, virtual imaging provided important contributions to determining the feasibility of different shunt procedures. However, in some patients experiencing portalvenous thrombosis or liver diffuse hemangioma, virtual methods were not as accurate as standard diagnostic procedures. Nevertheless, these tools facilitated simultaneous and continuous illustrations of the different vascular systems. CONCLUSIONS: Virtual imaging and planning procedures had an important impact on treatment strategies and outcomes in children with HVM. Their use as standard diagnostic tools in selected cases of HVM should be considered.

Technique of right hemihepatectomy preserving ventral right anterior section guided by area of hepatic venous drainage.

BACKGROUND: Although the consequences of partial venous outflow interruption have attracted only limited attention in liver surgery, maximal preservation of liver function after hepatic resection requires preservation of circulation in the remnant liver, especially hepatic vein drainage. METHODS: Data from 30 patients undergoing 3-dimensional imaging were analyzed to clarify the relationship between the area of the ventral right anterior section (RAS) and that drained by regional hepatic vein tributaries. The feasibility of our preliminary technique of right hemihepatectomy preserving the ventral RAS also was evaluated. RESULTS: The median estimated volume of the ventral RAS was 230 mL (range, 88-391). The average ratio of this estimated volume of the ventral RAS to total estimated liver volume was 18.0 +/- 4.9%. The median volume of the territory served by middle hepatic vein (MHV) tributaries draining the ventral RAS, expressed as a percentage of the whole volume of the ventral RAS, was 82.5%. Findings in fusion images of portal and hepatic vein territories demonstrated an area of MHV tributaries comparable with the ventral RAS area in 73.3% of all cases. As for the results of right hemihepatectomy with the ventral RAS preserved, no tumor was exposed on transection surfaces, and no recurrence took place within the preserved ventral RAS of the remnant liver. CONCLUSION: Procedures considering the importance of regional venous drainage offer the possibility of reducing the extent of surgery without loss of effectiveness.

Portal vein segmentation of a 3D-planning system for liver surgery--in vivo evaluation in a porcine model.

BACKGROUND: Computer systems allow the planning of complex liver operations. The segmentation of intrahepatic vessels builds the basis for the calculation of liver segments and resection proposals. For surgical use, it is essential to know the capabilities and limitations of the segmentation. The aim of this study was to determine the sensitivity and precision of the portal vein segmentation of a computer planning system for liver surgery in vivo. METHODS: Segmentations were performed with the software system HepaVision on computed tomography (CT) scan data of domestic pigs. An in situ corrosion cast of the portal vein served as the gold standard. The segmentation results of the portal vein and the corrosion cast were compared with regard to sensitivity, precision, and amount of short-circuit segmentations. RESULTS: The methodology demonstrated high resolution ex situ. The in vivo sensitivity of the portal vein segmentation was 100% for vessels of more than 5 mm in diameter and 82% for vessels of 3-4 mm. All segment branches were detected as well as 84% of the first subsegment branches with a diameter of more than 3 mm. The precision of the system was 100% for segment branches and 89% for the first subsegment vessels. The amount of internal short-circuit segmentations was less than 3.0%. No external short-circuits were found. CONCLUSION: The system has a high precision and sensitivity under clinical conditions. The segmentation is suitable for portal vein branches of the first and second order and for vessels of >/=3 mm in diameter.

Role of three-dimensional imaging in operative planning for hilar cholangiocarcinoma.

BACKGROUND: Complex, highly variable, anatomic relationships in the portal hilum complicate the surgical management at hilar cholangiocarcinoma. Preoperative three-dimensional (3D) imaging to stage the tumor and define anatomy may help in planning for curative resection. METHODS: Between 2003 and 2006, 20 consecutive patients with hilar cholangiocarcinoma underwent preoperative multidetector row computed tomography (MDCT) cholangiography; 3D images of the portal vein, hepatic artery, and bile ducts were created and viewed simultaneously. Longitudinal tumor extension was evaluated by direct cholangiography and 3D cholangiography, and contiguous spread by 2D computed tomography (CT). Of 20 patients, 15 underwent surgical resection. Liver resection was planned based on 3D imaging that allowed visualization of the relationship between the tumor and the umbilical portion of the left portal vein, or the bifurcation of the anterior and posterior branch of the right portal vein. Preoperative and operative findings were compared. RESULTS: All patients tolerated 3D CT without serious complication. The accuracy rates of longitudinal tumor extension, using the Bismuth-Corlette classification system, were 85% (11/13) and 87% (13/15) with direct cholangiography and 3D cholangiography, respectively. The sensitivity, specificity, and accuracy rates were 100%, 80%, and 87% for portal invasion and 75%, 91%, and 87% for hepatic arterial invasion. The number of bile duct orifices in the cut end of the hilar plate was estimated correctly in 13 of 15 patients. There were no operative deaths. Potentially curative resection was achieved in 14 of 15 patients. CONCLUSIONS: 3D images provide accurate information about the relationship between hilar cholangiocarcinoma and adjacent vessels. This technique is a powerful new tool for improving the proportion of potentially curative resection.

A pulsed electron gun for ultrafast electron diffraction at surfaces.

The construction of a pulsed electron gun for ultrafast reflection high-energy electron diffraction experiments at surfaces is reported. Special emphasis is placed on the characterization of the electron source: a photocathode, consisting of a 10 nm thin Au film deposited onto a sapphire substrate. Electron pulses are generated by the illumination of the film with ultraviolet laser pulses of femtosecond duration. The photoelectrons are emitted homogeneously across the photocathode with an energy distribution of 0.1 eV width. After leaving the Au film, the electrons are accelerated to kinetic energies of up to 15 keV. Focusing is accomplished by an electrostatic lens. The temporal resolution of the experiment is determined by the probing time of the electrons traveling across the surface which is about 30 ps. However, the duration of the electron pulses can be reduced to less than 6 ps.

Successful duct-to-duct biliary reconstruction after right hemihepatectomy. Operative planning using virtual 3D reconstructed images.

Accurate knowledge of partial anatomy is essential in hepatic surgery but is difficult to acquire. We describe the potential impact of a new technique for constructing three-dimensional virtual images of the portal vein, hepatic artery, and bile ducts and present a representative case. An 80-year-old man was suspected of having papillary cholangiocarcinoma arising in S8 of the liver and extending to the hepatic hilum intraluminaly. Right hemihepatectomy with bile duct resection was planned. However, it was uncertain whether duct-to-duct biliary reconstruction would be possible based on the appearance of the confluence of the right and left hepatic ducts on cholangiogram and conventional computed tomograph. Virtual three-dimensional images of the liver were constructed and revealed vascular and biliary anatomy. They showed that the upper margin of bile duct excision would be 19 mm from the umbilical point of the left portal vein, and that the site of the left branch of the caudate lobe bile duct could be preserved. Based on this information, we performed a sphincter-preserving biliary operation safely without complications. Planning complex biliary surgery may be improved by the use of virtual three-dimensional images of the liver. This approach is especially useful in candidates for postoperative regional chemotherapy.

Parenchyma transection in adult live donor liver transplantation: the virtual dilemma of "where to cut". Experience based on virtual 3-dimensional computed tomography imaging reconstructions.

BACKGROUND/AIMS: Adequate venous drainage is essential to prevent parenchyma congestion in graft and remnant livers after adult live donor liver transplantation (ALDLT). The areas particularly prone to congestion are the right and left medial sectors. The purpose of our study was to evaluate two types of liver transection techniques (Cantlie, Malagó) frequently encountered in ALDLT and to determine their resulting anatomical and functional liver graft volumes. METHODOLOGY: Livers from 58 potential live liver donors were subject to a virtual 3-dimensional liver partition for right graft hepatectomy. Anatomical (post-transectional) volumes of both right graft and left remnant livers in either liver partition group were initially estimated and corresponding anatomic-GVBWR for the graft hemiliver was calculated. Additionally the potential venous drainage impairment in the medial area of the graft, which was influenced by the two different transection planes, was estimated giving the baseline for the calculation of the functional-GVBWR of the graft. RESULTS: Computer analysis showed no statistically significant differences in the anatomical volumetric parameters between the two potential types of liver partition. However, virtual liver partition following the Cantlie line showed significant decrease of functional volumetric parameters for right liver graft, due to incidental detachment of the right-sided tributaries of middle hepatic vein. CONCLUSIONS: Image-based computer assistance allows for areas at risk for devascularization or venous congestion to be identified and calculated before parenchyma transection in ALDLT. According to the results of this study, minimal modifications of the transection line can provide significant increases in functional volumetric parameters by avoiding venous congestion in the marginal zone of the graft, drained by the middle hepatic vein.

Anatomical and physiological comparison of liver volumes among three frequent types of parenchyma transection in live donor liver transplantation.

BACKGROUND/AIMS: Adequate venous outflow is a prerequisite for successful live donor liver transplantation. Several techniques of liver transection have been established in both transplant and non-transplant hepatic surgery. The purpose of our study was to define and compare anatomical and physiological characteristics of venous drainage in the three most common types of liver transection techniques (Malagó, Cantlie, Pringle) encountered in live donor liver transplantation METHODOLOGY: Volumes of both graft and remnant livers as well as individual hepatic vein territories were calculated by means of virtual 3-dimensional reconstructions of computed tomography images obtained from 55 potential live liver donors using the software HepaVision (MeVis, Germany). Belonging to the middle hepatic vein (MHV) was assigned according to the largest territorial volume on either right or left hemilivers. Livers from all potential donors were subject to virtual splitting (n=55). Findings were subsequently confirmed intraoperatively in those who underwent donor resection (n=27). RESULTS: There were no statistically significant differences in hemiliver-volumes among the three types of liver partition. There was a predominance of MHV belonging to the right hemiliver: Malagó n=45 (82%) vs. Cantlie n=44 (80%) vs. Pringle n=44 (80%). Dominant right MHV hemiterritory showed a mean volume of 284-296 mL, accounting for 59-61% of total MHV volume. There were no significant differences among the three types of liver partition evaluated. CONCLUSIONS: Our results demonstrate the reliability of virtual 3-dimensional reconstructions based on standard anatomical landmarks for both surgical planning and graft volume calculations. We believe our technique will help prevent small-for-size grafting and liver insufficiency resulting from inaccurate volumetric calculations. Our findings also support the observation that improved venous outflow might be achieved by including the MHV with the right liver graft without disadvantaging the left liver remnant. It is our hope that all these findings will translate into enhanced donor and recipient safety.

Three-dimensional visualization and virtual simulation of resections in pediatric solid tumors.

PURPOSE: Three-dimensional visualization of solid tumors is possible because of high-resolution computed tomography and magnetic resonance imaging scans. However, additional preoperative information is often desirable in complex malignancies. For the first time, the authors present a model of preoperative 3-dimensional visualization and virtual resections in pediatric solid tumors. METHODS: Image analysis of various pediatric tumors was performed using the research software HepaVision2 (MeVis, Bremen). Organs, tumors, and the vascular system were extracted from multislice computed tomography scans. After hierarchical analysis of the vascular system, territories supplied or drained by the major vascular branches were calculated. Results were explored and virtual resections of organs were carried out using the research software InterventionPlanner (MeVis, Bremen). Data were correlated to intraoperative findings. RESULTS: Four hepatic malignancies, 4 renal tumors, and 3 other neoplasms were analyzed. The technique of 3-dimensional visualization was feasible for all investigated children (mean age 5 years and 9 months). Spatial relations between physiological and pathological structures were identified, and anatomical structures (vessels, tumor tissue, and organ parenchyma) were determined using colorimetric encoding. Virtual simulations of tumor resection were used successfully for planning of surgical procedures in the hepatic and renal tumors. CONCLUSIONS: The technique of 3-dimensional tumor visualization and virtual simulation of tumor resections provides the basis for a successful planning of complex tumor resections in children. The efficiency of these techniques should be further analyzed in series with higher numbers and differentiations of tumors.

Extended left hepatectomy--modified operation planning based on three-dimensional visualization of liver anatomy.

BACKGROUND: Based on the patient history of a 62-year-old man with a centrally located hepatocellular carcinoma we describe the potential influence of three-dimensional computed tomography (3D CT) on operation planning in extended left hepatectomy. METHOD AND RESULTS: By 3D reconstruction of the liver, not only variations of the intrahepatic vascular structure but also the number and extent of portal venous segments, as well as their relation to hepatic veins, can be visualized. Thus, areas at risk for either devascularization or venous congestion may be identified prior to liver resection. This is particularly important in extended hepatectomies with a small liver remnant, where already minor complications may have fatal consequences. CONCLUSION: In these resections, operation planning may be improved substantially by pre-operative 3D reconstruction.