Intraoperative three-dimensional fluoroscopic cholangiography

Precise intraoperative assessment of the architecture of the biliary tree could reduce lesions to intra- or extrahepatic bile ducts. The aim of this study was to test feasibility of intraoperative three-dimensional imaging during liver resections. Isocentric C-arm fluoroscopy acquires three-dimensional images during a 190 degrees orbital rotation. The bile ducts were displayed three-dimensionally by realtime rotational projections or multiplanar reconstructions. The technique was established ex vivo in a preserved cadaveric human liver. Intraoperative three-dimensional cholangiography was performed in five patients with centrally located liver malignancies. Complete data acquisition in 3 patients depicted precise anatomical details of the architecture of the biliary tree up to third order divisions. Biliary imaging can be improved by the application of real-time intraoperative three-dimensional cholangiography. For the development of computer-aided navigation in hepatobiliary procedures, this technique could be an important prerequisite for defining landmarks of the liver in a three-dimensional space.

Augmenting the effective field of view of optical tracking cameras--a way to overcome difficulties during intraoperative camera alignment

An Internet survey demonstrated the existence of problems related to intraoperative tracking camera set-up and alignment. It is hypothesized that these problems are a result of the limited field of view of today's optoelectronic camera systems, which is usually insufficiently large to keep the entire site of surgical action in view during an intervention. A method is proposed to augment a camera's field of view by actively controlling camera orientation, enabling it to track instruments as they are used intraoperatively. In an experimental study, an increase of almost 300% was found in the effective volume in which instruments could be tracked.

Prediction of spatial orientation and morphology of calcaneonavicular coalitions

BACKGROUND: Calcaneonavicular coalitions (CNC) have been reported to be associated with anatomical aberrations of either the calcaneus and/or navicular bones. These morphological abnormalities may complicate accurate surgical resection. Three-dimensional analysis of spatial orientation and morphological characteristics may help in preoperative planning of resection. MATERIALS AND METHODS: Sixteen feet with a diagnosis of CNC were evaluated by means of 3-D CT modeling. Three angles were defined that were expressed in relation to one reproducible landmark (lateral border of the calcaneus): the dorsoplantar inclination, anteroposterior inclination, and socket angle. The depth and width of the coalitions were measured and calculated to obtain the estimated contact surface. Three-dimensional reconstructions of the calcanei served to evaluate the presence, distortion or absence of the anterior calcaneal facet and presence of a navicular beak. The interrater correlations were assessed in order to obtain values for the accuracy of the measurement methods. Sixteen normal feet were used as controls for comparison of the socket angle; anatomy of the anterior calcaneal facet and navicular beak as well. RESULTS: The dorsoplantar inclination angle averaged 50 degrees (+/-17), the anteroposterior inclination angle 64 degrees (+/-15), and the pathologic socket angle 98 degrees (+/-11). The average contact area was 156 mm(2). Ninety-four percent of all patients in the CNC group revealed a plantar navicular beak. In 50% of those patients the anterior calcaneal facet was replaced by the navicular portion and in 44% the facet was totally missing. In contrast, the socket angle in the control group averaged 77 degrees (+/-18), which was found to be statistically different than the CNC group (p = 0.0004). Only 25% of the patients in the control group had a plantar navicular beak. High, statistically significant interrater correlations were found for all measured angles. CONCLUSION: Computer-aided CT analysis and reconstructions help to determine the spatial orientations of CNC in space and provide useful information in order to anticipate morphological abnormalities of the calcaneus and navicular.

Accuracy of navigated surgery of the pelvis after surface matching with an a-mode ultrasound probe

Computer-aided surgery (CAS) allows for real-time intraoperative feedback resulting in increased accuracy, while reducing intraoperative radiation. CAS is especially useful for the treatment of certain pelvic ring fractures, which necessitate the precise placement of screws. Flouroscopy-based CAS modules have been developed for many orthopedic applications. The integration of the isocentric flouroscope even enables navigation using intraoperatively acquired three-dimensional (3D) data, though the scan volume and imaging quality are limited. Complicated and comprehensive pathologies in regions like the pelvis can necessitate a CT-based navigation system because of its larger field of view. To be accurate, the patient's anatomy must be registered and matched with the virtual object (CT data). The actual precision within the region of interest depends on the area of the bone where surface matching is performed. Conventional surface matching with a solid pointer requires extensive soft tissue dissection. This contradicts the primary purpose of CAS as a minimally invasive alternative to conventional surgical techniques. We therefore integrated an a-mode ultrasound pointer into the process of surface matching for pelvic surgery and compared it to the conventional method. Accuracy measurements were made in two pelvic models: a foam model submerged in water and one with attached porcine muscle tissue. Three different tissue depths were selected based on CT scans of 30 human pelves. The ultrasound pointer allowed for registration of virtually any point on the pelvis. This method of surface matching could be successfully integrated into CAS of the pelvis.

[Navigation and robotics of the lateral skull base]

Computer-aided microscopic surgery of the lateral skull base is a rare intervention in daily practice. It is often a delicate and difficult minimally invasive intervention, since orientation between the petrous bone and the petrous bone apex is often challenging. In the case of aural atresia or tumors the normal anatomical landmarks are often absent, making orientation more difficult. Navigation support, together with imaging techniques such as CT, MR and angiography, enable the surgeon in such cases to perform the operation more accurately and, in some cases, also in a shorter time. However, there are no internationally standardised indications for navigated surgery on the lateral skull base. Miniaturised robotic systems are still in the initial validation phase.

Novel autoantigens immunogenic in COPD patients

Background Chronic obstructive pulmonary disease (COPD) is a respiratory inflammatory condition with autoimmune features including IgG autoantibodies. In this study we analyze the complexity of the autoantibody response and reveal the nature of the antigens that are recognized by autoantibodies in COPD patients. Methods An array of 1827 gridded immunogenic peptide clones was established and screened with 17 sera of COPD patients and 60 healthy controls. Protein arrays were evaluated both by visual inspection and a recently developed computer aided image analysis technique. By this computer aided image analysis technique we computed the intensity values for each peptide clone and each serum and calculated the area under the receiver operator characteristics curve (AUC) for each clone and the separation COPD sera versus control sera. Results By visual evaluation we detected 381 peptide clones that reacted with autoantibodies of COPD patients including 17 clones that reacted with more than 60% of the COPD sera and seven clones that reacted with more than 90% of the COPD sera. The comparison of COPD sera and controls by the automated image analysis system identified 212 peptide clones with informative AUC values. By in silico sequence analysis we found an enrichment of sequence motives previously associated with immunogenicity. Conclusion The identification of a rather complex humoral immune response in COPD patients supports the idea of COPD as a disease with strong autoimmune features. The identification of novel immunogenic antigens is a first step towards a better understanding of the autoimmune component of COPD.

Differential diagnosis of CT focal liver lesions using texture features, feature selection and ensemble driven classifiers

The aim of the present study is to define an optimally performing computer-aided diagnosis (CAD) architecture for the classification of liver tissue from non-enhanced computed tomography (CT) images into normal liver (C1), hepatic cyst (C2), hemangioma (C3), and hepatocellular carcinoma (C4). To this end, various CAD architectures, based on texture features and ensembles of classifiers (ECs), are comparatively assessed.

Smart Foundry - Informationstechnische Unterstützung der Planung, Konstruktion und Fertigung von Formen für den Metallguss

Die Europäische Gießereiindustrie besteht zu einem großen Teil aus Klein- und Mittelständischen Unternehmen, die in Summe einen bedeutenden Anteil der produzierenden Industrie Europas bilden. Traditionell sind diese Unternehmen lediglich in einem geringen Umfang an Forschungs- und Entwicklungsaktivitäten beteiligt, was vielerorts den Einsatz veralteter Technologie und der damit verbundenen Prozesse zur Folge hat.

Projektbericht: VITA

In traditionellen Übungsarrangements (z.B. handkorrigierte Hausaufgaben oder vorlesungsbegleitende Übungsgruppen) erhalten Studierende ihre Ergebnisse mit Zeitverzögerung, während der Kurs inzwischen fortschreitet. Dadurch besteht die Gefahr, dass Defizite nicht wahrgenommen oder nicht korrigiert werden. Traditionelle Übungsarrangements erfordern bei sinnvollem Einsatz (v. a. kleine Übungsgruppe) eine Personalkapazität, wie sie insbesondere an Fachhochschulen nicht existiert. Ein zweites Problem, das zum Teil infolge des mangelnden Übens auftritt, besteht darin, dass viele Studierende Lehrveranstaltungen nicht nachbereiten. Viele Studierende versuchen stattdessen, sich den Vorlesungsstoff in einem kurzen Zeitraum vor der Prüfung anzueignen, was, wenn es überhaupt gelingt, nicht zu einer nachhaltigen Verankerung der Inhalte führt. In der Folge fehlen in den Nachfolgeveranstaltungen die Grundlagen, die in den vorausgegangenen Veranstaltungen hätten gelegt werden sollen.