Facilitating real-time volume interaction.

We report on efforts to provide high-level intuitive tools that exploit commodity-based computing to facilitate real-time and distributed interactions with volumetric data. These efforts include an open source volume-rendering library, a portable volume visualization application framework, and parallel volume-rendering exploiting commodity-based hardware. We present our design and implementations, as well as examples of some of the various groups currently utilizing these tools, and discuss the tradeoffs of our developments versus existing techniques.

Temporal bone dissection simulation--an update.

We report on our continued development of a virtual simulation for temporal bone dissection that provides stereoscopic display, haptic feedback, and aural simulation into a straightforward, comprehensive learning environment. The multimodal interface provides a seamless simulation for non-deterministic drilling and cutting of bone in the surgical context, as well as an intuitive interface for the intelligent tutor for learning regional anatomy. We present novel methodologies for integrating multimodal and multiresolution data sets, including extension to functional and structural segmentation. We will present our initial efforts to validate this environment. Through continued iterations, it is our hope that the system will provide a valuable tool for training future otologic surgeons as well as an environment for the quantitative evaluation of surgical skill.

A draft annotation and overview of the human genome.

BACKGROUND: The recent draft assembly of the human genome provides a unified basis for describing genomic structure and function. The draft is sufficiently accurate to provide useful annotation, enabling direct observations of previously inferred biological phenomena. RESULTS: We report here a functionally annotated human gene index placed directly on the genome. The index is based on the integration of public transcript, protein, and mapping information, supplemented with computational prediction. We describe numerous global features of the genome and examine the relationship of various genetic maps with the assembly. In addition, initial sequence analysis reveals highly ordered chromosomal landscapes associated with paralogous gene clusters and distinct functional compartments. Finally, these annotation data were synthesized to produce observations of gene density and number that accord well with historical estimates. Such a global approach had previously been described only for chromosomes 21 and 22, which together account for 2.2% of the genome. CONCLUSIONS: We estimate that the genome contains 65,000-75,000 transcriptional units, with exon sequences comprising 4%. The creation of a comprehensive gene index requires the synthesis of all available computational and experimental evidence.

Assembly, annotation, and integration of UNIGENE clusters into the human genome draft.

The recent release of the first draft of the human genome provides an unprecedented opportunity to integrate human genes and their functions in a complete positional context. However, at least three significant technical hurdles remain: first, to assemble a complete and nonredundant human transcript index; second, to accurately place the individual transcript indices on the human genome; and third, to functionally annotate all human genes. Here, we report the extension of the UNIGENE database through the assembly of its sequence clusters into nonredundant sequence contigs. Each resulting consensus was aligned to the human genome draft. A unique location for each transcript within the human genome was determined by the integration of the restriction fingerprint, assembled genomic contig, and radiation hybrid (RH) maps. A total of 59,500 UNIGENE clusters were mapped on the basis of at least three independent criteria as compared with the 30,000 human genes/ESTs currently mapped in Genemap'99. Finally, the extension of the human transcript consensus in this study enabled a greater number of putative functional assignments than the 11,000 annotated entries in UNIGENE. This study reports a draft physical map with annotations for a majority of the human transcripts, called the Human Index of Nonredundant Transcripts (HINT). Such information can be immediately applied to the discovery of new genes and the identification of candidate genes for positional cloning.

Interactive medical data on demand: a high-performance imaged-based approach across heterogeneous environments.

Medical data in image format continues to increase in both size and complexity. We have integrated advanced techniques in visualization, networked computing, and interface design to improve methods for accessing medical data comprising high-resolution images for reconstructions into three-dimensional volumetric representations. We present two approaches to handle the range of low to high-end client platforms, support visualization functionality, and provide the ability to manipulate very large data over heterogeneous computing and networking environments. We present examples of its use for clinical, research, and educational purposes and discuss future extensions.

Virtual temporal bone dissection simulation.

We have developed a working prototype system for the virtual simulation of temporal bone dissection. The system offers a paradigm from traditional practices by integrating technological advances to provide a safer and more cost effective way to learn fundamental techniques used in temporal bone surgeries. We present our methods to provide a real-time interactive volumetric system that obviates the need for physical materials in initial training, and provides a more accessible way for residents to practice and to increase exposure to pathological variance. Finally, we discuss ways to extend this work to more advanced resident training, presurgical planning, and surgical documentation.

Interactive volume visualizations for synchronous and asynchronous remote collaboration.

The value of information acquisition is not simply to acquire data at increased precision, but to make these data both available and usable to as many specialists as possible. We have developed a working prototype for intuitive realtime interaction over the Internet. Current scenarios include use by expert head and neck surgeons, for use in preoperative assessment of head and neck cancers, and remote synchronous collaboration scenarios such as expert-expert and expert-referring physician. This prototype demonstrates a shared virtual environment that allows multiple users to interactively manipulate large volumetric data sets across long distances. The system is easily extensible to many other applications that utilize discrete data sampling and thus is readily extensible to a wide range of scientific investigations.

Functional endoscopic sinus surgery training simulator.

OBJECTIVE/HYPOTHESIS: To determine the efficacy of a haptic (force feedback) device and to compare isosurface and volumetric models of a functional endoscopic sinus surgery (FESS) training simulator. STUDY DESIGN: A pilot study involving faculty and residents from the Department of Otolaryngology at The Ohio State University. METHODS: Objective trials evaluated the haptic device's ability to perceive three-dimensional shapes (stereognosis) without the aid of image visualization. Ethmoidectomy tasks were performed with both isosurface and volumetric FESS simulators, and surveys compared the two models. RESULTS: The haptic device was 77% effective for stereognosis tasks. There was a preference toward the isosurface model over the volumetric model in terms of visual representation, comfort, haptic-visual fidelity, and overall performance. CONCLUSIONS: The FESS simulator uses both visual and haptic feedback to create a virtual reality environment to teach paranasal sinus anatomy and basic endoscopic sinus surgery techniques to ear, nose, and throat residents. The results of the current study showed that the haptic device was accurate in and of itself, within its current physical limitations, and that the isosurface-based simulator was preferred.

Using advanced simulation technology for cranial base tumor evaluation.

Skull base tumors are considered one of the most difficult pathologic entities to diagnose and treat. The physician is heavily dependent on imaging studies to determine the best form of treatment. As imaging technology becomes more advanced, the physician will need to be able to intuitively explore the complex data. Such intuitive exploration requires the use of high performance computer hardware and software. Issues related to this concept and a summary of current work in this area are presented.

A comparative analysis of integrating visual representations with haptic displays.

As further advances in visual display technologies and force feedback devices are integrated in virtual systems, questions remain: What level of reality does the system provide to the user? Is the environment convincing enough to engage the user and to maximize transfer? Are the visual and haptic displays fully integrated to provide seamless operation in the simulated environment? Does the system provide not only the ability to navigate through a simulated environment, but also realistic interaction with instrumentation and structures? We report on our advances in developing a virtual simulation system for training in functional endoscopic sinus surgery (FESS). Specifically, we will present work on subject trials exploring the realism provided by integrated visual and haptic displays, and compare and contrast surface vs. volume representation for presenting realistic models of the anatomy for surgical interaction.

Development of the force-feedback model for an epidural needle insertion simulator.

The Ohio Supercomputer Center and the Department of Anesthesiology at the OSU Medical Center have developed a computer-based simulation system for use in training anesthesiology residents in the technique of placing a needle for an epidural block. Although the simulator has been well regarded, the fidelity of the haptic feedback is limited because it is based on subjective expert-user evaluation and not on objective model-based or data-based empirical methods. Only a single degree of freedom for force-feedback is required. However, the simulation must be able to accurately portray the force required to puncture each layer of tissue in order to feel realistic. The purpose of the research described in this paper was to devise a methodology for creating empirically based realistic force-feedback models for the epidural needle insertion procedure using MRI data and biomechanical data from materials testing.

A volumetric approach to virtual simulation of functional endoscopic sinus surgery.

Advanced display technologies have made the virtual exploration of relatively complex models feasible in many applications. Unfortunately, only a few human interfaces allow natural interaction with the environment. Moreover, in surgical applications, such realistic interaction requires real-time rendering of volumetric data-placing an overwhelming performance burden on the system. We report on a collaboration of an interdisciplinary group developing a virtual reality system that provides intuitive interaction with volume data by employing real-time volume rendering and force feedback (haptic) sensations. We describe our rendering methods and the haptic devices and explain its utility of this system in the real-world application of Endoscopic Sinus Surgery (ESS) simulation.

ENT endoscopic surgical training simulator.

This paper describes work in progress on the design and development of a prototype simulator for minimally invasive otolaryngology surgical training. The anatomy of the paranasal sinuses is geometrically complex and dangerously close to the brain and orbits, making this procedure challenging to practice and difficult to learn. We discuss the potential role of computer simulation to enhance and accelerate acquisition of surgical skills. The design goals of the prototype include high-fidelity simulation of the endoscopic imagery and haptic cues of surgical palpation. The prototype enables endoscopic navigation and limited interactive tissue manipulation and dissection tasks on a virtual patient using realistic replicas of surgical tools. We present an overview of the system architecture with a discussion of the technological challenges, design issues and current status of the efforts.

Visualization of compression neuropathies through volume deformation.

This paper describes an interdisciplinary effort to simulate and visualize the mechanisms involved in compression neuropathies, specifically tissue deformation occurring during vaginal delivery. These neuropathies often evolve into chronic pelvic pain. We present our methodologies of using high resolution magnetic resonance acquisitions from submillimeter pulse sequences to develop interactive computer simulations based on physically plausible volume models to drive 3D simulations of childbirth. This effort will elucidate tissue movements and mechanics involved in pain disorders and better explain the etiology of these disorders.

A haptic interface for virtual simulation of endoscopic surgery.

Virtual reality can be described as a convincingly realistic and naturally interactive simulation in which the user is given a first person illusion of being immersed within a computer generated environment While virtual reality systems offer great potential to reduce the cost and increase the quality of medical training, many technical challenges must be overcome before such simulation platforms offer effective alternatives to more traditional training means. A primary challenge in developing effective virtual reality systems is designing the human interface hardware which allows rich sensory information to be presented to users in natural ways. When simulating a given manual procedure, task specific human interface requirements dictate task specific human interface hardware. The following paper explores the design of human interface hardware that satisfies the task specific requirements of virtual reality simulation of Endoscopic surgical procedures. Design parameters were derived through direct cadaver studies and interviews with surgeons. Final hardware design is presented.

Cranial base tumor visualization through high-performance computing.

Tumors of the skull base in general are considered among the more difficult head and neck pathological entities to treat surgically; some surgeons, in fact, consider lesions in this area inoperable. The most appropriate and safest surgical approach to lesions of the anterior and lateral skull base can be devised only with accurate and precise pre-operative assessment. The literature demonstrates the constant evolution of and search for more efficient less invasive, and safe surgical approaches to this region. With the development of a more exact three-dimensional, interactive anatomical "road map" for each patient's disease and anatomy, the skull base surgeon can not only achieve a more accurate pre-operative assessment leading to a less invasive and less morbid approach, but also can continue to develop and refine new approaches without fear of actual morbidity and mortality. An interdisciplinary team approach, the advent and continued development of faster high performance computers, and the development of new and innovative rendering algorithms can lead to surgical simulation. A prototype of an interactive system has been developed. The system will be iteratively modified through a stepwise evaluation of its clinical usefulness by continually reassessing the system with clinical trials. The current state of the system and the potential benefits are presented.