Portal Supply and Venous Drainage of the Caudate Lobe in the Healthy Human Liver: Virtual Three-Dimensional Computed Tomography Volume Study.

OBJECTIVE: The venous vascular anatomy of the caudate lobe is exceptional. The purpose of this study was to assess portal inflow and venous outflow volumes of the caudate lobe. METHODS: Extrahepatic (provided by the first-order branches) versus intrahepatic (provided by the second- to third-order branches) portal inflow, as well as direct (via Spieghel veins) versus indirect (via hepatic veins) venous drainage patterns were analyzed in virtual 3-D liver maps in 140 potential live liver donors. RESULTS: The caudate lobe has a greater intrahepatic than extrahepatic portal inflow volume (mean 55 ± 26 vs. 45 ± 26%: p = 0.0763), and a greater extrahepatic than intrahepatic venous drainage (mean 54-61 vs. 39-46%). Intrahepatic drainage based on mean estimated values showed the following distribution: middle > inferior (accessory) > right > left hepatic vein. CONCLUSIONS: Sacrifice of extrahepatic caudate portal branches can be compensated by the intrahepatic portal supply. The dominant outflow via Spieghel veins and the negligible role of left hepatic vein in caudate venous drainage may suggest reconstruction of caudate outflow via Spieghel veins in instances of extended left hemiliver live donation not inclusive of the middle hepatic vein. The anatomical data and the real implication for living donors must be further verified by clinical studies.

Benchmarking framework for myocardial tracking and deformation algorithms: an open access database.

In this paper we present a benchmarking framework for the validation of cardiac motion analysis algorithms. The reported methods are the response to an open challenge that was issued to the medical imaging community through a MICCAI workshop. The database included magnetic resonance (MR) and 3D ultrasound (3DUS) datasets from a dynamic phantom and 15 healthy volunteers. Participants processed 3D tagged MR datasets (3DTAG), cine steady state free precession MR datasets (SSFP) and 3DUS datasets, amounting to 1158 image volumes. Ground-truth for motion tracking was based on 12 landmarks (4 walls at 3 ventricular levels). They were manually tracked by two observers in the 3DTAG data over the whole cardiac cycle, using an in-house application with 4D visualization capabilities. The median of the inter-observer variability was computed for the phantom dataset (0.77 mm) and for the volunteer datasets (0.84 mm). The ground-truth was registered to 3DUS coordinates using a point based similarity transform. Four institutions responded to the challenge by providing motion estimates for the data: Fraunhofer MEVIS (MEVIS), Bremen, Germany; Imperial College London - University College London (IUCL), UK; Universitat Pompeu Fabra (UPF), Barcelona, Spain; Inria-Asclepios project (INRIA), France. Details on the implementation and evaluation of the four methodologies are presented in this manuscript. The manually tracked landmarks were used to evaluate tracking accuracy of all methodologies. For 3DTAG, median values were computed over all time frames for the phantom dataset (MEVIS=1.20mm, IUCL=0.73 mm, UPF=1.10mm, INRIA=1.09 mm) and for the volunteer datasets (MEVIS=1.33 mm, IUCL=1.52 mm, UPF=1.09 mm, INRIA=1.32 mm). For 3DUS, median values were computed at end diastole and end systole for the phantom dataset (MEVIS=4.40 mm, UPF=3.48 mm, INRIA=4.78 mm) and for the volunteer datasets (MEVIS=3.51 mm, UPF=3.71 mm, INRIA=4.07 mm). For SSFP, median values were computed at end diastole and end systole for the phantom dataset(UPF=6.18 mm, INRIA=3.93 mm) and for the volunteer datasets (UPF=3.09 mm, INRIA=4.78 mm). Finally, strain curves were generated and qualitatively compared. Good agreement was found between the different modalities and methodologies, except for radial strain that showed a high variability in cases of lower image quality.

Transhilar passage in right graft live donor liver transplantation: intrahilar anatomy and its impact on operative strategy.

The passage through the hilar plate during right graft live donor liver transplantation (LDLT) can have dangerous consequences for both donors and recipients. The purpose of our study was to delineate hilar transection and biliary reconstruction strategies in right graft LDLT, with special consideration of central and peripheral hilar anatomical variants. A total of 71 consecutive donors underwent preoperative three-dimensional (3D) CT reconstructions and virtual 3D hepatectomies. A three-modal hilar passage strategy was applied, and its impact on operative strategy analyzed. In 68.4% of cases, type I and II anatomical configurations allowed for an en block hilar transection with simple anastomotic reconstructions. In 23.6% of cases, donors had "difficult" type II and types III/IV hilar bile duct anatomy that required stepwise hilar transections and complex graft biliary reconstructions. Morbidity rates for our early (A) and recent (B) experience periods were 67% and 39%, respectively. (1) Our two-level classification and 3D imaging technique allowed for donor-individualized transhilar passage. (2) A stepwise transhilar passage was favored in types III and IV inside the right-sided hilar corridor. (3) Reconstruction techniques showed no ameliorating effect on early/late biliary morbidity rates.

Liver remnant hypertrophy induction--how often do we really use it in the time of computer assisted surgery?

PURPOSE: To evaluate the significance of the hypertrophy concept in patients requiring extended liver resections for colorectal metastasis in the time of computer assisted surgery. METHODS: Retrospective analysis of patient collective undergoing major liver surgery. 2D CT, 3D CAS with Fraunhofer MeVis Sofware. Portal vein embolisation (PVE) with the Amplazer Plug, portal vein ligation (PVL) as 1. Stage operative procedure. RESULTS: 2D CT data identified 29 patients out of 319 (2002-2009) to be at risk for liver failure after resection. After 3D CAS analysis and virtual operation planning, only 7/29 were at true risk and were submitted to portal vein occlusion (PVO). Another 5 patients were submitted to the hypertrophy concept for intraoperative finding of insufficient parenchyma quality. In total, 12 patients underwent PVO (6 PVE/6 PVL). 9/12 patients went to stage 2 and were successfully operated. There was no difference in future remnant liver volume (FRLV) gain or waiting time to step 2 between the groups, though survival was better in the PVE group. CONCLUSION: PVO is an effective approach if the patient's future remnant liver (FRL) is too small on 2D CT volumetry. 3D CAS has great impact on the analysis of FRL capacity and in augmenting resectability - in our experience only patients with insufficient FRLV on the virtual resection plan have to take the risk of PVO to maintain the chance of liver resection.

Rapid image recognition of body parts scanned in computed tomography datasets.

AIM: Automatic CT dataset classification is important to efficiently create reliable database annotations, especially when large collections of scans must be analyzed. METHOD: An automated segmentation and labeling algorithm was developed based on a fast patient segmentation and extraction of statistical density class features from the CT data. The method also delivers classifications of image noise level and patient size. The approach is based on image information only and uses an approximate patient contour detection and statistical features of the density distribution. These are obtained from a slice-wise analysis of the areas filled by various materials related to certain density classes and the spatial spread of each class. The resulting families of curves are subsequently classified using rules derived from knowledge about features of the human anatomy. RESULTS: The method was successfully applied to more than 5,000 CT datasets. Evaluation was performed via expert visual inspection of screenshots showing classification results and detected characteristic positions along the main body axis. Accuracy per body region was very satisfactory in the trunk (lung/liver >99.5% detection rate, presence of abdomen >97% or pelvis >95.8%) improvements are required for zoomed scans. CONCLUSION: The method performed very reliably. A test on 1,860 CT datasets collected from an oncological trial showed that the method is feasible, efficient, and is promising as an automated tool for image post-processing.

Fast Estimation of the Vascular Cooling in RFA Based on Numerical Simulation.

We present a novel technique to predict the outcome of an RF ablation, including the vascular cooling effect. The main idea is to separate the problem into a patient independent part, which has to be performed only once for every applicator model and generator setting, and a patient dependent part, which can be performed very fast. The patient independent part fills a look-up table of the cooling effects of blood vessels, depending on the vessel radius and the distance of the RF applicator from the vessel, using a numerical simulation of the ablation process. The patient dependent part, on the other hand, only consists of a number of table look-up processes. The paper presents this main idea, along with the required steps for its implementation. First results of the computation and the related ex-vivo evaluation are presented and discussed. The paper concludes with future extensions and improvements of the approach.

[Three-dimensional reconstruction of central lung tumors based on CT data]. / Dreidimensionale Rekonstruktion von zentralen Lungentumoren basierend auf CT-Daten : Erste klinische Erfahrungen First clinical experiences.

BACKGROUND: CT scanning of the lungs is the standard procedure for preoperative evaluation of central lung tumors. The extent of the tumor and infiltration of central lung structures or lung segments are decisive parameters to clarify whether surgery is possible and the extent of resection. With computer-assisted methods for the segmentation of anatomical structures based on CT data (Fraunhofer MeVis, Bremen) an enhanced, three-dimensional selective visualization is now possible. PATIENTS AND METHODS: From August 2007 through June 2009, 22 patients with central lung tumors were treated at the department of thoracic surgery, University of Schleswig-Holstein, campus Lübeck. There were 15 males and 7 females with a mean age of 60.2 years (range 41-74 years), 18 patients had a long history of smoking, while 4 patients had never smoked. Of the patients 20 had a primary lung carcinoma, 1 patient had local recurrent lung cancer after lobectomy and 1 patient had a central lung metastasis from a non-pulmonary primary carcinoma. A multi-slice detector computer tomogram (MSDCT) scan was performed in all cases. All data were three-dimensionally reconstructed and visualized using special computer-aided software (Fraunhofer MeVis, Bremen). Pulmonary lung function tests, computed postoperative lung volume, bronchoscopic findings, general condition of the patients and the three-dimensionally reconstructed CT data were used for an individual risk analysis and surgical planning. RESULTS: According to the risk analysis 14 out of the 22 patients were surgically treated, 7 patients were staged as functionally inoperable and 1 as technically inoperable. A pneumonectomy was performed in 5 cases, a lobectomy/bilobectomy in 4 cases, an extended lobectomy in 3 cases and 1 case each of a wedge resection and a sleeve resection. Of the 14 patients 2 were classified as stage Ia/b, 7 patients as stage IIa/b and 5 patients as stage IIIa. The median length of time spent in hospital was 8.5±33 days and the mortality rate was 0%. The three-dimensional visualization of the tumor and its anatomical relationship to central pulmonary vessels and the airway system was feasible in all cases. The three-dimensional reconstruction was confirmed in all cases by surgical exploration. CONCLUSION: Three-dimensional reconstruction of CT scan data is a new and promising method for preoperative presentation and risk analysis of central lung tumors. The three-dimensional visualization with anatomical reformatting and color-coded segmentation enables the surgeon to make a more precise strategic approach for central lung tumors.

Formation of venous collaterals and regeneration in the donor remnant liver: volumetric analysis and three-dimensional visualization.

PURPOSE: We sought was to quantify and visualize the regeneration of the remnant liver after living donor liver transplantation using computed tomographic (CT) data. METHODS: For the evaluation of preoperative and follow-up data, we developed a software assistant that was able to compute the volume growth of the remnant liver and liver territories as well as visualize the individual growth of hepatic vessels over time. The software was applied to CT data of 20 donors who underwent right hepatectomy including the middle hepatic vein with at least 3 follow-up examinations in the first year after transplantation. RESULTS: After donation of a right lobe graft, the remnant liver regenerated by an average 77% of the original volume within the first 3 postoperative months and to 86% within the first year. The growth of the left lateral segments was increased compared with that of segment IV in all cases. The visualization showed the growth of the portal vein and the hepatic veins. With the simultaneous display of pre- and postoperative results, it was possible to detect the formation of collaterals between truncated segment IVb veins and the veins of segment IVa or of the left lateral lobe. CONCLUSION: The software-assisted analysis of follow-up data yielded additional insight into territorial liver regeneration after living donor liver transplantation and allowed for reliable detection of relevant hepatic vein collaterals using CT data.

Ex situ quantification of the cooling effect of liver vessels on radiofrequency ablation.

PURPOSE: To quantify the cooling effect of hepatic vessels on liver radiofrequency (RF) ablation ex situ. METHODS: Bipolar RF applicators (diameter = 1.8 mm, electrode length = 30 mm) were inserted parallel to perfused glass tubes (diameter = 5 and 10 mm; flow = 250-1,800 ml/min) at distances of 5 and 10 mm in porcine livers ex vivo. RF ablation was performed at 30 W/15 kJ. RF lesions were analyzed by measuring the maximum (r (max)) and minimum radius (r (min)) and the lesion area. RESULTS: Glass tubes without flow showed no influence on RF lesions, whereas perfused glass tubes had a significant cooling effect on lesions. r (min) was reduced to 50% at 5 mm applicator-to-vessel distance and the lesion area was reduced from 407 to 321 mm(2) (p < 0.001). There was no significant influence of glass tube diameter or flow volume on any of the analyzed parameters. CONCLUSIONS: Cooling effects of intrahepatic vessels could be simulated in an ex situ model. Cooling effects should be taken into account in RF ablation within 10 mm distance to major liver vessels regardless of blood flow volume or vessel diameter. Surgical RF ablation with temporary blood flow occlusion should be considered in such constellations.

[Virtual hepatic surgery - computer-assisted operation planning on the 3-dimensional reconstructed liver]. / 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.

[Generating statements at whole-body imaging with a workflow-optimized software tool--first experiences with multireader analysis]. / Befunderstellung bei der Ganzkörperbildgebung mittels einer workflowoptimierten Befundungssoftware--Erste Erfahrungen einer Multireader-Analyse.

INTRODUCTION: Due to technical innovations in sectional diagram methods, whole-body imaging has increased in importance for clinical radiology, particularly for the diagnosis of systemic tumor disease. Large numbers of images have to be evaluated in increasingly shorter time periods. The aim was to create and evaluate a new software tool to assist and automate the process of diagnosing whole-body datasets. MATERIAL AND METHODS: Thirteen whole-body datasets were evaluated by 3 readers using the conventional system and the new software tool. The times for loading the datasets, examining 5 different regions (head, neck, thorax, abdomen and pelvis/skeletal system) and retrieving a relevant finding for demonstration were acquired. Additionally a Student T-Test was performed. For qualitative analysis the 3 readers used a scale from 0 - 4 (0 = bad, 4 = very good) to assess dataset loading convenience, lesion location assistance, and ease of use. Additionally a kappa value was calculated. RESULTS: The average loading time was 39.7 s (+/- 5.5) with the conventional system and 6.5 s (+/- 1.4) (p < 0.01) with the new software tool. For the different regions (conventional system/new software tool), the time reduction for readers 1, 2, and 3 were as follows: in the head region 35.9 % (p < 0.01)/49.9 % (p < 0.01)/54.3 % (p < 0,01), in the neck region 48.5 % (p < 0.01)/52.6 % (p < 0.01)/59.4 % (p < 0.05), in the thorax region 59.1 % (p < 0.01)/56.2 % (p < 0.05)/62.1 % (p < 0.05), in the abdominal region 61.9 % (p < 0.01)/62.7 % (p < 0.05)/47.9 % (p < 0.01) and in the pelvis region 73.1 % (p < 0.01)/63.7 % (p < 0.05)/55 % (p < 0.01), respectively. 148.2 s (+/- 94.8) compared to 2.5 s (+/- 0.5) were required to retrieve a previously described finding (p < 0.01). With and without the new software tool the same number of metastases was found (p < 0.01, k > 0.9). The qualitative analysis showed a significant advantage with respect to convenience (p < 0.01, k > 0.9). CONCLUSION: Use of the new software can achieve a significant time savings when working with whole-body datasets with a constant quality of findings and a significant advantage with respect to convenience. As a result, the problem of evaluating examinations with thousands of images can be approached systematically.

Graft selection algorithm based on congestion volume for adult living donor liver transplantation.

A major concern in adult-to-adult living donor liver transplantation is the selection of graft type; that is, is it is better to use the right lobe with or without the middle hepatic vein (MHV)? This choice has a considerable impact on donor safety, vascular reconstruction and graft function in the recipient. To facilitate making an appropriate choice, on the basis of a preliminary study (n = 17), we herein propose a graft selection algorithm using three parameters: graft-to-recipient body weight ratio (GRWR), percentage remnant liver volume (%RLV) and estimated congestion ratio (ECR). The algorithm was evaluated with 50 consecutive cases with respect to postoperative liver function of donors and recipients and survival of recipients. Postoperative recovery was comparable between the two groups (p = NS). The overall cumulative 18-month survival rate was 86.7% for the 'with MHV graft group', and 76.1% for the gwithout MHV graft grouph (p = NS). For 41 cases (82%), graft types were chosen according to the algorithm, whereas the remaining 9 cases (18%) needed detailed discussion of donor, recipient and operative factors. In conclusion, we constructed a graft selection algorithm based on congestion volume, which will contribute to objective graft-type selection in adult-to-adult LDLT.

Computer-assisted operative planning in adult living donor liver transplantation: a new way to resolve the dilemma of the middle hepatic vein.

An adequate venous outflow is essential for securing viability of both graft and remnant in adult living donor liver transplantation (ALDLT). Seventy-five potential live liver donors were evaluated for LDLT by means of an "all-in-one" CT, which defined the biliary tree, portal vein, hepatic artery, and hepatic vein anatomy. The acquired data sets were further analysed by means of the software HepaVision (MeVis, Germany). Only a minority (29%) of potential donors were found to have a vascular and biliary anatomy consistent with the classically described "normal" patterns. The vast majority (71%) had "anatomical variations". Thirty-nine (52%) donors underwent ALDLT hepatectomy. The right hepatic vein was dominant in 64 cases, representing 48 +/- 6% of the total liver volume (TLV). The middle hepatic vein was dominant in 11 cases, making up 40 +/- 8% of the TLV. The left hepatic vein was never dominant. The volume contribution of the middle hepatic vein (MHV) was 114-782 ml for the right and 87-419 ml for the left hemiliver. Computer-assisted planning allows for the 3D reconstruction of the vascular and biliary anatomy, automatic calculation of the total and territorial liver volumes, and risk analysis of hepatic vein dominance relationships. This comprehensive data acquisition supports preoperative evaluation and provides a high degree of safety for donors and improved outcomes for recipients.

Uncertainty in diffusion tensor based fibre tracking.

BACKGROUND: Diffusion tensor imaging and related fibre tracking techniques have the potential to identify major white matter tracts afflicted by an individual pathology or tracts at risk for a given surgical approach. However, the reliability of these techniques is known to be limited by image distortions, image noise, low spatial resolution, and the problem of identifying crossing fibres. This paper intends to bridge the gap between the requirements of neurosurgical applications and basic research on fibre tracking uncertainty. METHOD: We acquired echo planar diffusion tensor data from both 1.5 T and 3.0 T scanners. For fibre tracking, an extended deflection-based algorithm is employed with enhanced robustness to impaired fibre integrity such as caused by diffuse or infiltrating pathological processes. Moreover, we present a method to assess and visualize the uncertainty of fibre reconstructions based on variational complex Gaussian noise, which provides an alternative to the bootstrap method. We compare fibre tracking results with and without variational noise as well as with artificially decreased image resolution and signal-to-noise. FINDINGS: Using our fibre tracking technique, we found a high robustness to decreased image resolution and signal-to-noise. Still, the effects of image quality on the tracking result will depend on the employed fibre tracking algorithm and must be handled with care, especially when being used for neurosurgical planning or resection guidance. An advantage of the variational noise approach over the bootstrap technique is that it is applicable to any given set of diffusion tensor images. CONCLUSIONS: We conclude that the presented approach allows for investigating the uncertainty of diffusion tensor imaging based fibre tracking and might offer a perspective to overcome the problem of size underestimation observed by existing techniques.

Temporal horn index and volume of medial temporal lobe atrophy using a new semiautomated method for rapid and precise assessment.

BACKGROUND AND PURPOSE: Quantitative markers of Alzheimer disease (AD), particularly in the early stages, are needed for clinical assessment and monitoring. We have evaluated a novel method to segment and visualize the ventricular system and obtain volumetric measures thereof. The temporal horn volume (THV) and index in patients with mild cognitive impairment (MCI) and in those with AD were evaluated. METHODS: High-resolution T1-weighted volume imaging was performed in 52 subjects (21 patients with MCI, 10 with AD, and 21 healthy control subjects). An interactive watershed transformation and semiautomated histogram analysis were implemented to produce segmented THV and temporal horn indices (THI) (ratio of THV to lateral ventricular volume). RESULTS: Cerebral ventricular and temporal horn size could be semiautomatically quantified from all 52 datasets. The method was fast and rater-independent. Qualitative ventricular inspections using surface rendering shading could uncover atrophic process with enlargement of the whole and especially temporal horn volume. Both THV and THI of patients with AD were significantly larger than those of patients with MCI or control subjects (P < .005). There was no significant difference in THV and THI between patients with MCI or control subjects (P > .05). There was a significant correlation between the neuropsychologic performance and both THI and THV across groups (P < .01). CONCLUSION: THV and THI could be used as markers of AD in the clinical environment and are expected to be helpful in monitoring therapeutic intervention.

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.

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.

Computerized CT-based 3D visualization technique in living related liver transplantation.

INTRODUCTION: For living donor liver transplantation (LDLT) accurate diagnostic workup is essential. Multiple imaging approaches are currently used. Problems arise in the assessment of vascular and bile duct anatomy, liver graft volume, and vascular territories involved. A 3D visualization system that improves anatomic assessment, allows interactive surgery planning, and acts as an intraoperative guide with enhanced precision is required. Refinements in computed tomography (CT) technology with the introduction of multidetector-row CT scanners and implementation of mathematical methods on computerized digital data has enabled CT-based 3D visualizations. MATERIALS AND METHODS: Sixteen LDLT candidates and three LDLT recipients were assessed by multislice CT examination. Image processing of the digital raw data for 3D visualization included segmentation and calculation of center lines. A hierarchical mathematical model representing the vascular and biliary tree was created. This allowed calculation of individual vascular territories. RESULTS: 3D CT-based visualization in LDLT facilitates diagnostic workup with high accuracy for analyses of vascular and bile duct variants, volumetry, and assessment of the optimal surgical splitting line of the living donor liver. Resultant areas of either arterial devascularization or venous congestion can be displayed and quantified preoperatively. The diagnostic method is of major impact on patient selection and directly influences intraoperative surgical guidance. The currently practiced "multiple imaging approach" approach, especially with regard to invasive diagnostics, can be avoided in the future.

Detection of tumour infiltration in axonal fibre bundles using diffusion tensor imaging.

We present a method for the detection and quantification of white matter infiltration from human brain tumours based on Diffusion Tensor Imaging (DTI). Since white matter destruction alters the local diffusion properties, DTI has the potential to sensitively detect tumour infiltration and to quantify the degree thereof. Here, we consider three tumour patients with gliomas, two with and one without contralateral tumour progress. We use DTI to identify specific fibre systems, where infiltration has to be assessed. On this basis, the problem of arbitrary region of interest definition is solved such that tumour infiltration can be reliably quantified in particular fibre bundles. It is demonstrated at the Corpus Callosum (CC) and the Pyramidal Tract (PT) that fibre bundle infiltration can be well detected by specific visualisation techniques of diffusion tensor data. Infiltration of the CC is quantified by using a reliable method for the determination of diffusion properties inside particular fibre bundles. For an age normalised quantification of white matter infiltration we introduce the Integrity Index, which measures the diffusion anisotropy inside an infiltrated fibre bundle normalised by the diffusion anisotropy in a specific region of healthy fibre tissue. It turns out that the quantification of CC infiltration correlates with contralateral tumour progression and has the potential to serve as a surrogate marker for this process, which is crucial for surgical therapy decisions and intervention planning.

A reliable and efficient method for cerebral ventricular volumetry in pediatric neuroimaging.

OBJECTIVES: Cerebral ventricular volume has the potential to become an important parameter in quantitative neurological diagnosis. However, no accepted methodology for routine clinical use exists to date. We sought a robust, reproducible, and fast technique to evaluate cerebral ventricular volume in young children. METHODS: We describe a novel volumetric methodology to segment and visualize intracerebral fluid spaces and to quantify ventricular volumes. The method is based on broadly available T1 weighted volumetric magnetic resonance (MR) imaging, an interactive watershed transform, and a fully automated histogram analysis. We evaluated this volumetric methodology with 34 clinical volumetric MR datasets from non-sedated children (age 6-7 y) with a history of prematurity and low birth weight (< or = 1500 g) obtained during a prospective study. RESULTS: The methodology, with adaptation for small ventricular size, was capable of evaluating all 34 of the pediatric datasets for cerebral ventricular volume. The method was a) robust for normal and pathological anatomy, b) reproducible, c) fast with less than five minutes for image analysis, and d) equally applicable to children and adults. CONCLUSIONS: Clinical brain ventricular volume calculations in non-sedated children can be performed using routine MR imaging besides efficient three-dimensional segmentation and histogram analysis with results that are robust and reproducible.