Showing papers by "Andrea Schenk published in 2004"

3D CT modeling of hepatic vessel architecture and volume calculation in living donated liver transplantation.

Abstract: The aim of this study was to evaluate a software tool for non-invasive preoperative volumetric assessment of potential donors in living donated liver transplantation (LDLT). Biphasic helical CT was performed in 56 potential donors. Data sets were post-processed using a non-commercial software tool for segmentation, volumetric analysis and visualisation of liver segments. Semi-automatic definition of liver margins allowed the segmentation of parenchyma. Hepatic vessels were delineated using a region-growing algorithm with automatically determined thresholds. Volumes and shapes of liver segments were calculated automatically based on individual portal-venous branches. Results were visualised three-dimensionally and statistically compared with conventional volumetry and the intraoperative findings in 27 transplanted cases. Image processing was easy to perform within 23 min. Of the 56 potential donors, 27 were excluded from LDLT because of inappropriate liver parenchyma or vascular architecture. Two recipients were not transplanted due to poor clinical conditions. In the 27 transplanted cases, preoperatively visualised vessels were confirmed, and only one undetected accessory hepatic vein was revealed. Calculated graft volumes were 1110 +/- 180 ml for right lobes, 820 ml for the left lobe and 270 +/- 30 ml for segments II+III. The calculated volumes and intraoperatively measured graft volumes correlated significantly. No significant differences between the presented automatic volumetry and the conventional volumetry were observed. A novel image processing technique was evaluated which allows a semi-automatic volume calculation and 3D visualisation of the different liver segments.

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

Abstract: 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.

In-vivo-Evaluation der hepatischen Gefäßsegmentierung eines 3D-Planungssystems für die in-situ-Ablation von Lebertumoren

Abstract: Objective: The oncologically safe application of thermal in-situ ablation techniques is limited by a lack of precise prediction and online monitoring of the resulting destruction. Knowledge about intrahepatic vessel structure is important for therapy planning. The aim of the current study was to validate in-vivo an interdisciplinary developed 3D planning system for the in-situ ablation of liver tumors with regard to intrahepatic vessel segmentation. Methods: 10 domestic pigs were used (40 kg, endotracheal anaesthesia, cross-laparatomy). After surgical preparation of the extra-hepatic vessels, an angiographie catheter was implanted in the portal vein. A computed tomography (CT, Siemens Somatom l6, 1 mm slices, DICOM2 data acquisition) was performed an each pig. The scans were carried out using a peripheral venous contrast medium (CM) and a selective CM-CT via the implanted portal vein catheter. After removal of the liver, a corrosion cast with acrylic resin via the portal vein catheter was prepared in-situ. The image data was transferred to the planning system and the vessel segmentation was carried out. The validation was performed by comparing the corrosion cast and the computed segmentation. Results: A segment classification of the pig liver was established. Standard CTs allowed for segmentation of the portal vein branches down to 3rd degree subsegment vessels. The comparison between the patterns of the corrosion cast and the peripheral veins and selective segmentation showed complete correlation to the 1st degree subsegment vessels and a correlation of 97% to the 2nd degree subsegment vessels. Incorrect segmentations, i.e. assignment of adjacent vessel systems, or aborts of segmentation were not abserved. Conclusions: 1.) A 3D computer planning system was developed for predicting thermal lesions resulting from in-situ ablation. 2.) The algorithms for vessel segmentation resulted in a precise depiction of the in-vivo intrahepatic vessel structure. 3.) This planning system facilitates the calculated use of thermal in-situ ablation techniques.