Virtual dental surgery as a new educational tool in dental school.

PURPOSE: The virtual environment of the Voxel-Man simulator that was originally designed for virtual surgical procedures of the middle ear has been adapted to intraoral procedures. To assess application of the simulator to dentistry, virtual apicectomies were chosen as the pilot-test model. METHODS: A group of 53 dental students provided their impressions after virtual simulation of apicectomies in the Voxel-Man simulator. RESULTS: Fifty-one of the 53 students recommended the virtual simulation as an additional modality in dental education. The students indicated that the force feedback (e.g. simulation of haptic pressure), spatial 3D perception, and image resolution of the simulator were sufficient for virtual training of dental surgical procedures. CONCLUSION: The feedback from dental students involved in this pilot-test has encouraged our interdisciplinary group to continue further development of the simulator with the goal of creating new training strategies in dental and medical education.

Virtual reality: a new paranasal sinus surgery simulator.

OBJECTIVES/HYPOTHESIS: Virtual surgical training systems are of growing value. Current prototypes for endonasal sinus surgery simulation are very expensive or lack running stability. No reliable system is available to a notable number of users yet. The purpose of this work was to develop a dependable simulator running on standard PC hardware including a detailed anatomic model, realistic tools and handling, stereoscopic view, and force feedback. STUDY DESIGN: Descriptive. METHODS: A three-dimensional voxel model was created based on a high-resolution computed tomography study of a human skull, from which the bony structures were segmented. The mucosa and organs at risk were added manually. The model may be manipulated with virtual surgical tools controlled with a low-cost haptic device, which is also used to adjust microscopic or endoscopic views. Visualization, haptic rendering, and tissue removal are represented with subvoxel resolution. RESULTS: The handling of the model is convincing. The haptic device provides a realistic feeling regarding the interaction between tool tip and anatomy. Three-dimensional orientation and the look and feel of virtual surgical interventions get close to reality. CONCLUSIONS: The newly developed system is a stable, fully operational simulator for sinus surgery based on standard PC hardware. Besides the limitations of a low-cost haptic device, the presented system is highly realistic regarding anatomy, visualization, manipulation, and the appearance of the tools. It is mainly intended for gaining surgical anatomy knowledge and for training navigation in a complex anatomical environment. Learning effects, including motor skills, have yet to be quantified.

[18F]FDG and [18F]FLT PET-CT and MR imaging of human neuroblastomas in a SCID mouse xenograft model.

BACKGROUND: Finding new therapeutic agents is of great clinical interest in neuroblastoma research because prognosis of children with disseminated stages of disease is still poor. As xenograft mouse models are frequently used for studying anticancer drugs in vivo, small animal imaging is an important method of monitoring in anticancer research. MATERIALS AND METHODS: SCID mice inoculated with human neuroblastoma SK-N-SH cells were examined with positron-emission tomography-computed tomography (PET-CT) using [18F]fluorodeoxyglucose (FDG) or [18F]fluoro-L-thymidine (FLT) and with magnetic resonance imaging (MRI). RESULTS: All neuroblastomas were detected by MRI. In PET-CT imaging, no tumour was visualized with [18F]FDG, but 13 out of 14 (93%) were found with [18F]FLT. Uptake of [18F]FLT was significantly associated with tumour weight. Necrotic areas could not be identified either by MR imaging or on PET-CT scans. CONCLUSION: Both MR and PET-CT imaging with [18F]FLT are highly qualified for the detection of neuroblastomas grown in SCID mice. However, [18F]FDG, which is the standard tracer in clinical PET-CT imaging, is not suited for PET-CT imaging in the neuroblastoma model.

Computer-based anatomy a prerequisite for computer-assisted radiology and surgery.

RATIONALE AND OBJECTIVES: The aim of the study is to show the possibilities opened up by three-dimensional (3D) computer-based models of the human body for education in anatomy, training of radiological and endoscopic examinations, and simulation of surgical procedures. MATERIALS AND METHODS: Based on 3D data sets obtained from the Visible Human and/or clinical cases, virtual body models are created that provide an integrated spatial and symbolic description of the anatomy by using interactive color/intensity-based segmentation, ray casting visualization with subvoxel resolution, a semantic network for knowledge modeling, and augmented QuickTime VR (Apple Computer, Inc, Cupertino, CA) movies for presentation. RESULTS: From these models, various radiological, endoscopic, or haptic manifestations of the body can be derived. This is shown with examples from anatomy teaching, correlation of x-ray images with 3D anatomy for education in radiology, gastrointestinal endoscopy, correlation of ultrasound images with 3D anatomy in endoscopic ultrasonography, and simulation of drilling in temporal bone surgery. CONCLUSION: The presented models provide a means for realistic training in interpretation of radiological and endoscopic images of the human body. Furthermore, certain surgical procedures may be simulated realistically. Used as a complement to the current curriculum, these models have the potential to greatly decrease education times and costs.

Virtual study of the endocranial morphology of the matrix-filled cranium from Eliye Springs, Kenya.

This paper provides the first endocranial description of the matrix-filled archaic Homo sapiens cranium from Eliye Springs, Kenya. Using CT-based 3D reconstruction, the virtually cleaned endocranial surface allowed for the assessment of more than 30 metrical and nonmetrical features, most of which are considered of phylogenetic importance. The VOXEL-MAN program used was most valuable in describing and analyzing the morphological conditions. Since many of the features have not been widely or virtually studied, a small sample of late Pleistocene/early Holocene skulls from East Africa was similarly analyzed for insight into recent variation. The comparisons between Eliye Springs and the modern African specimens showed that the endocranial morphology of this probably later Middle Pleistocene hominid falls into, or close to, the modern ranges of variation for most features. This study also addresses the problems of variation and phylogenetic significance of many of the features, and highlights the need for basic studies on the variability and relevance of such endocranial traits in human evolution.