Biomedical subjects

Mary Rasmussen

Publications and source records attributed to Mary Rasmussen.

9 recordsLinked to original sources

PubMed2006

New tools for sculpting cranial implants in a shared haptic augmented reality environment.

New volumetric tools were developed for the design and fabrication of high quality cranial implants from patient CT data. These virtual tools replace time consuming physical sculpting, mold making and casting steps. The implant is designed by medical professionals in tele-immersive collaboration. Virtual clay is added in the virtual defect area on the CT data using the adding tool. With force feedback the modeler can feel the edge of the defect and fill only the space where no bone is present. A carving tool and a smoothing tool are then used to sculpt and refine the implant. To make a physical evaluation, the skull with simulated defect and the implant are fabricated via stereolithography to allow neurosurgeons to evaluate the quality of the implant. Initial tests demonstrate a very high quality fit. These new haptic volumetric sculpting tools are a critical component of a comprehensive tele-immersive system.

Computer-Aided Design↗

PubMed2005

Reconstruction and exploration of three-dimensional confocal microscopy data in an immersive virtual environment.

An immersive virtual environment for interactive three-dimensional reconstruction and exploration of confocal microscopy data is presented. For some structures automatic alignment of serial sections can lead to geometric distortions. The superior visual feedback of a Virtual Reality system is used to aid in registering and aligning serial sections interactively. An ImmersaDesk Virtual Reality display system is used for display and interaction with the volumetric confocal data. Detailed methods for handling both single-section and multi-section confocal data are described.

Humans↗

PubMed2005

Desktop and conference room VR for physicians.

Virtual environments such as the CAVE and the ImmersaDesk, which are based on graphics supercomputers or workstations, are large and expensive. Most physicians have no access to such systems. The recent development of small Linux personal computers and high-performance graphics cards has afforded opportunities to implement applications formerly run on graphics supercomputers. Using PC hardware and other affordable devices, a VR system has been developed which can sit on a physician's desktop or be installed in a conference room. Affordable PC-based VR systems are comparable in performance with expensive VR systems formerly based on graphics supercomputers. Such VR systems can now be accessible to most physicians. The lower cost and smaller size of this system greatly expands the range of uses of VR technology in medicine.

Microcomputers↗

PubMed2005

Simulation of color deficiency in virtual reality.

Color deficiency protanopia is simulated in a virtual home environment. A color database is created to set the corresponding relation between each color for normal vision and for protanopia. Based on this database, a second texture system is set up for the home model. The proper texture system is used according to the user's choice on the interactive menu.

Color Vision Defects↗

PubMed2004

Three dimensional virtual reality model of the normal female pelvic floor.

The anatomy of the pelvic floor is complex and difficult to visualize from conventional two-dimensional anatomy pictures. The goal of this project was to establish the methods necessary to develop a static three-dimensional virtual reality model of the normal female pelvic floor from high-resolution magnetic resonance imaging (MRI) scans. An asymptomatic nulliparous 23-year-old female with no urinary incontinence symptoms underwent a high-resolution pelvic floor MRI scan. Selected pelvic floor structures were manually segmented: bladder, urethra, vagina, uterus, cervix, levator ani, obturator externus, obturator internus, and pubic bone. With high-resolution scans, accurate segmentation of the structures was possible. The completed models were displayed on an ImmersaDesk Virtual Reality system and three clinicians verified their accuracy. Stereovision glasses were used to enhance the model while a receiver tracked head position. Three-dimensional virtual reality models of the female pelvic floor can enhance our understanding of anatomy and physiology of this complex part of the body. They can be used as tools for both research and teaching, facilitating improved treatment of pelvic floor pathologies.

Adult↗

PubMed2003

Virtual reality: new method of teaching anorectal and pelvic floor anatomy.

PURPOSE: A clear understanding of the intricate spatial relationships among the structures of the pelvic floor, rectum, and anal canal is essential for the treatment of numerous pathologic conditions. Virtual-reality technology allows improved visualization of three-dimensional structures over conventional media because it supports stereoscopic-vision, viewer-centered perspective, large angles of view, and interactivity. We describe a novel virtual reality-based model designed to teach anorectal and pelvic floor anatomy, pathology, and surgery. METHODS: A static physical model depicting the pelvic floor and anorectum was created and digitized at 1-mm intervals in a CT scanner. Multiple software programs were used along with endoscopic images to generate a realistic interactive computer model, which was designed to be viewed on a networked, interactive, virtual-reality display (CAVE or ImmersaDesk). A standard examination of ten basic anorectal and pelvic floor anatomy questions was administered to third-year (n = 6) and fourth-year (n = 7) surgical residents. A workshop using the Virtual Pelvic Floor Model was then given, and the standard examination was readministered so that it was possible to evaluate the effectiveness of the Digital Pelvic Floor Model as an educational instrument. RESULTS: Training on the Virtual Pelvic Floor Model produced substantial improvements in the overall average test scores for the two groups, with an overall increase of 41 percent (P = 0.001) and 21 percent (P = 0.0007) for third-year and fourth-year residents, respectively. Resident evaluations after the workshop also confirmed the effectiveness of understanding pelvic anatomy using the Virtual Pelvic Floor Model. CONCLUSION: This model provides an innovative interactive educational framework that allows educators to overcome some of the barriers to teaching surgical and endoscopic principles based on understanding highly complex three-dimensional anatomy. Using this collaborative, shared virtual-reality environment, teachers and students can interact from locations world-wide to manipulate the components of this model to achieve the educational goals of this project along with the potential for virtual surgery.

Anal Canal↗

PubMed2003

Three-dimensional reconstruction of extravascular matrix patterns and blood vessels in human uveal melanoma tissue: techniques and preliminary findings.

PURPOSE: Looping patterns rich in laminin are present in tissue samples of primary aggressive human uveal melanomas and their metastases. Because these extravascular patterns connect to blood vessels and transmit fluid in vitro and in vivo, the three-dimensional configuration of these patterns has been the subject of considerable speculation. In the current study, methods were devised to describe the three-dimensional configuration of looping extravascular matrix patterns in archival human uveal melanoma tissue. METHODS: Twenty-five serial 4-microm-thick sections from primary uveal melanoma tissue were labeled with fluorescence-tagged laminin and examined by confocal microscopy to generate a Z-series within each 4-microm-thick section. The z-series from each section was stacked using an immersive three-dimensional environment (ImmersaDesk; Fakespace, Kitchener, Ontario, Canada) to allow for precise alignment and compensation for distortion artifact. RESULTS: Extravascular matrix patterns that appeared to form loops in two dimensions were shown to represent thin wrappings around branching and twisting cylindrical groupings of melanoma cells. Blood vessels joined with some of these laminin-positive cylindrical wrappings. CONCLUSIONS: In this preliminary study, periodic acid-Schiff (PAS)-positive laminin-rich looping patterns in two-dimensional tissue sections appear to outline cylindrical branching packets of melanoma cells rather than spheroidal nests. The conduction of fluid through this extravascular system may provide a novel delivery system for contrast and diagnostic agents.

Antigens, CD34↗

PubMed2002

Tele-Immersive medical educational environment.

By combining teleconferencing, tele-presence, and Virtual Reality, the Tele-Immersive environment enables master surgeons to teach residents in remote locations. The design and implementation of a Tele-Immersive medical educational environment, Teledu, is presented in this paper. Teledu defines a set of Tele-Immersive user interfaces for medical education. In addition, an Application Programming Interface (API) is provided so that developers can easily develop different applications with different requirements in this environment. With the help of this API, programmers only need to design a plug-in to load their application specific data set. The plug-in is an object-oriented data set loader. Methods for rendering, handling, and interacting with the data set for each application can be programmed in the plug-in. The environment has a teacher mode and a student mode. The teacher and the students can interact with the same medical models, point, gesture, converse, and see each other.

Computer Communication Networks↗

PubMedDate not supplied

The virtual nose: a 3-dimensional virtual reality model of the human nose.

BACKGROUND: The 3-dimensionally complex interplay of soft tissue, cartilaginous, and bony elements makes the mastery of nasal anatomy difficult. Conventional methods of learning nasal anatomy exist, but they often involve a steep learning curve. Computerized models and virtual reality applications have been used to facilitate teaching in a number of other complex anatomical regions, such as the human temporal bone and pelvic floor. We present a 3-dimensional (3-D) virtual reality model of the human nose. METHODS: Human cadaveric axial cross-sectional (0.33-mm cuts) photographic data of the head and neck were used. With 460 digitized images, individual structures were traced and programmed to create a computerized polygonal model of the nose. Further refinements to this model were made using a number of specialized computer programs. This 3-D computer model of the nose was then programmed to operate as a virtual reality model. RESULTS: Anatomically correct 3-D model of the nose was produced. High-resolution images of the "virtual nose" demonstrate the nasal septum, lower lateral cartilages, middle vault, bony dorsum, and other structural details of the nose. Also, the model can be combined with a separate virtual reality model of the face and its skin cover as well as the skull. The user can manipulate the model in space, examine 3-D anatomical relationships, and fade superficial structures to reveal deeper ones. CONCLUSIONS: The virtual nose is a 3-D virtual reality model of the nose that is accurate and easy to use. It can be run on a personal computer or in a specialized virtual reality environment. It can serve as an effective teaching tool. As the first virtual reality model of the nose, it establishes a virtual reality platform from which future applications can be launched.

Humans↗