Konrad Mühler

The Medical Exploration Toolkit: An Efficient Support for Visual Computing in Surgical Planning and Training

Application development is often guided by the usage of software libraries and toolkits. For medical applications, the toolkits currently available focus on image analysis and volume rendering. Advanced interactive visualizations and user interface issues are not adequately supported. Hence, we present a toolkit for application development in the field of medical intervention planning, training, and presentation-the MEDICALEXPLORATIONTOOLKIT (METK). The METK is based on the rapid prototyping platform MeVisLab and offers a large variety of facilities for an easy and efficient application development process. We present dedicated techniques for advanced medical visualizations, exploration, standardized documentation, and interface widgets for common tasks. These include, e.g., advanced animation facilities, viewpoint selection, several illustrative rendering techniques, and new techniques for object selection in 3D surface models. No extended programming skills are needed for application building, since a graphical programming approach can be used. The toolkit is freely available and well documented to facilitate the use and extension of the toolkit.

Reusable visualizations and animations for surgery planning

For surgical planning, the exploration of 3D visualizations and 2D slice views is essential. However, the generation of visualizations which support the specific treatment decisions is very tedious. Therefore, the reuse of once designed visualizations for similar cases can strongly accelerate the process of surgical planning. We present a new technique that enables the easy reuse of both medical visualization types: 3D scenes and 2D slice views. We introduce the keystates as a concept to describe the state of a visualization in a general manner. They can be easily applied to new datasets to create similar visualizations. Keystates can be shared between surgeons of one specialization to reproduce and document the planning process for collaborative work. Furthermore, animations can support the surgeon on individual exploration and are also useful in collaborative environments, where complex issues must be presented in a short time. Therefore, we provide a framework, where animations can be visually designed by surgeons during their exploration process without any programming or authoring skills. We discuss several transitions between different visualizations and present an application from clinical routine.

The LiverSurgeryTrainer: training of computer-based planning in liver resection surgery

AbstractPurpose The training of liver surgeons depends on local conditions such as the specialization of the clinic, the spectrum of cases, and the instructing surgeons. We present the LiverSurgeryTrainer a software application to support the training of prospective surgeons in preoperative decision making. Methods The LiverSurgeryTrainer visualizes radiological images, volumetric information, and interactive 3D models of patients’ liver anatomy. In addition, it provides special interaction techniques and tools to perform individual resections on the training data. To assess the correctness of decisions made by the learner, comments and decisions from experienced liver surgeons are provided for each case. To complete the case, additional material concerning the actual surgery (e.g., videos, reports) is presented. The application workflow is derived from a scenario-based design process and is based on an instructional design model. Results The LiverSurgeryTrainer was evaluated in several steps. A formative usability evaluation identified workflow and user interface flaws that were resolved in further development process. A summative evaluation shows the improvement of the LiverSurgeryTrainer in nearly all analyzed aspects. First results of a learning success evaluation show that learners experience a learning effect. Conclusion Our training system allows surgeons to train procedures and interaction techniques for computer-based planning of liver interventions. The evaluations showed acceptance and usability.

METK — The Medical Exploration Toolkit

In the following we will describe concept and realization of the Medical Exploration Toolkit — the METK. The METK is designed for loading, visualizing and exploring segmented medical data sets. It is a framework of several modules based on the free MeVisLab, a development environment for medical image processing and visualization. The framework is platform-independent and freely available. We will also present several different applications, developed with the METK.

Skriptbasierte Animationen für die Operationsplanung und Ausbildung

Ziel dieses Beitrages ist die Generierung von Animationen aus patientenindividuellen, segmentierten CT- und MRT- Datensatzen. Die Animationsgenerierung erfolgt auf der Basis von Skripten. Dafur wurde eine Skriptsprache entwickelt, die die Anwendung eines einzigen Skriptes auf mehrere unterschiedliche Datensatze ermoglicht. Zusatzlich erlaubt die Skriptsprache die Definition von Ersetzungsvorschriften. Dies gestattet die Abstraktion von Anweisungen hin zu allgemeinen Beschreibungen von Animationsablaufen, die auch weniger versierte Nutzer erstellen konnen. Die Animationen werden sowohl in der Operationsplanung als auch in der medizinischen Ausbildung genutzt.

Automatische Annotation medizinischer 2D- und 3D-Visualisierungen

Wir stellen ein Framework vor, mit dem medizinische 2D- und 3D-Visualisierungen automatisch annotiert werden konnen. Annotationstexte wie St beirukturbenennungen oder Kurzbefunde werden so in der Darstellung platziert, dass sie gut lesbar sind und keine anderen Texte oder Strukturen verdecken. Weiterhin fuhren wir Techniken ein, mit denen sich eine Uberfrachtung von Schichtbildern mit Annotationen vermeiden lassen. Unser System kommt sowohl in der chirurgischen OP-Planung wie auch in medizinischen Ausbildungssystemen zum Einsatz.

Automatische Kamerapositionierung für intra-operative Visualisierungen in der onkologischen Leberchirurgie

In diesem Beitrag wird ein Verfahren vorgestellt, mit dessen Hilfe automatisch gute Blickpunkte auf dreidimensionale Planungsmodelle fur die Leberchirurgie berechnet werden konnen. Das Verfahren passt die Position der virtuellen Kamera wahrend einer Operation dynamisch an, insbesondere im Falle einer Aktualisierung von onkologischen Planungsdaten durch neue intra-operative Befunde.

Interactive medical volume visualizations for surgical online applications

For surgical planning, the exploration of 3d visualizations and 2d slice views is essential. We introduce a new technique to bring visualizations of 3d scenes of any kind and 2d image stacks generated by CT or MRI into the web. We pre-render 3d scenes from different perspectives and show these images during user interaction in a Flash based framework. Therewith we can create a 3d spatial relation. We support different zoom levels and can provide different presets for visualizations. The new technique is used to provide complex and enhanced 3d visualizations for surgical therapy planning and educational purposes as well as for evaluation of new visualization techniques.

Automatische Kamerapositionierung in komplexen medizinischen 3D-Visualisierungen

In diesem Beitrag wird ein Verfahren vorgestellt, mit dessen Hilfe optimale Blickpunkte fur die Betrachtung anatomischer Strukturen in komplexen 3D-Visualisierungen berechnet werden konnen. Der optimale Blickpunkt wird uber verschiedene gewichtete Bewertungs-parameter in Echtzeit ermittelt. Berucksichtigt werden u.a. Sichtbarkeit und Wichtigkeit der uberdeckenden Strukturen. Das Verfahren wird in zwei Systemen fur die medizinische Ausbildung und Therapieplanung angewendet.