Informed by modern imaging techniques, current medical navigation systems support physicians during a variety of interventions, such as needle-based operations. During these, an abundance of information is often displayed on monitors placed in positions that are uncomfortable for the operator to view. In this article, we address these issues with the concept and prototype of a customized flexible display that is placed on the patient’s body to provide the essential information at just the right location. We present an empirical evaluation comparing the flexible display against a control condition using a standard interventional monitor setup and an additional condition that combines both. Our results show that the flexible display significantly reduces task load while improving overall usability. Furthermore, we found indications that the flexible display reduces task completion time while also observing a negative effect on accuracy, which needs to be balanced carefully.

Abstract In this paper, we present a rapid prototyping framework for GPU‐based volume rendering. Therefore, we propose a dynamic shader pipeline based on the SuperShader concept and illustrate the design decisions. Also, important requirements for the development of our system are presented. In our approach, we break down the rendering shader into areas containing code for different computations, which are defined as freely combinable, modularized shader blocks. Hence, high‐level changes of the rendering configuration result in the implicit modification of the underlying shader pipeline. Furthermore, the prototyping system allows inserting custom shader code between shader blocks of the pipeline at run‐time. A suitable user interface is available within the prototyping environment to allow intuitive modification of the shader pipeline. Thus, appropriate solutions for visualization problems can be interactively developed. We demonstrate the usage and the usefulness of our framework with implementations of dynamic rendering effects for medical applications.

Percutaneous radiofrequency ablation (RFA) is becoming a standard minimally invasive clinical procedure for the treatment of liver tumors. However, planning the applicator placement such that the malignant tissue is completely destroyed, is a demanding task that requires considerable experience. In this work, we present a fast GPU-based real-time approximation of the ablation zone incorporating the cooling effect of liver vessels. Weighted distance fields of varying RF applicator types are derived from complex numerical simulations to allow a fast estimation of the ablation zone. Furthermore, the heat-sink effect of the cooling blood flow close to the applicator's electrode is estimated by means of a preprocessed thermal equilibrium representation of the liver parenchyma and blood vessels. Utilizing the graphics card, the weighted distance field incorporating the cooling blood flow is calculated using a modular shader framework, which facilitates the real-time visualization of the ablation zone in projected slice views and in volume rendering. The proposed methods are integrated in our software assistant prototype for planning RFA therapy. The software allows the physician to interactively place virtual RF applicator models. The real-time visualization of the corresponding approximated ablation zone facilitates interactive evaluation of the tumor coverage in order to optimize the applicator's placement such that all cancer cells are destroyed by the ablation.

Abstract Percutaneous radiofrequency (RF) ablation is a minimally invasive, image‐guided therapy for the treatment of liver tumors. The assessment of the ablation area (coagulation) is performed to verify the treatment success as an essential part of the therapy. Traditionally, pre‐ and post‐interventional CT images are used to visually compare the shape, size, and position of tumor and coagulation. In this work, we present a novel visualization as well as a navigation tool, the so‐called tumor map. The tumor map is a pseudo‐cylindrical mapping of the tumor surface onto a 2D image. It is used for a combined visualization of all ablation zones of the tumor to allow a reliable therapy assessment. Additionally, the tumor map serves as an interactive tool for intuitive navigation within the 3D volume rendering of the tumor vicinity as well as with familiar 2D viewers.

Abstract We present novel interactive methods for the visualization of multimodal volume data as used in neurosurgical therapy planning. These methods allow surgeons to explore multimodal volumes and focus on functional data and lesions. Computer graphics techniques are proposed to create expressive visualizations at interactive frame rates to reduce time‐consuming and complex interaction with the medical data. Contributions of our work are the distance‐based enhancements of functional data and lesions which allows the surgeon to perceive functional and anatomical structures at once and relate them directly to the intervention. In addition we propose methods for the visual exploration of the path to the structures of interest, to enhance anatomical landmarks, and to provide additional depth indicators. These techniques have been integrated in a visualization prototype that provides interaction capabilities for finding the optimal therapeutic strategy for the neurosurgeon.