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PubMed1997

Virtual reality exposure therapy.

It has been proposed that virtual reality (VR) exposure may be an alternative to standard in vivo exposure. Virtual reality integrates real-time computer graphics, body tracking devices, visual displays, and other sensory input devices to immerse a participant in a computer-generated virtual environment. Virtual reality exposure is potentially an efficient and cost-effective treatment of anxiety disorders. VR exposure therapy reduced the fear of heights in the first controlled study of virtual reality in treatment of a psychiatric disorder. A case study supported the efficacy of VR exposure therapy for the fear of flying. The potential for virtual reality exposure treatment for these and other disorders is explored, and therapeutic issues surrounding the delivery of VR exposure are discussed.

Fear↗

PubMed1994

Three-dimensional display in the evaluation and performance of neurosurgery without a stereotactic frame: more than a pretty picture?

Display of three-dimensionally rendered images derived from radiological data sets is often suggested to be useful for surgical and radiation treatment planning in neurosurgery. Nevertheless, physicians will often note (off the record) that these rendered images are 'just a pretty picture' and are not clinically useful. This paper will discuss our three-dimensional rendering and quantitative analysis software and its primary use in evaluating and utilizing frameless stereotactic methodologies. A variety of concepts and techniques will be discussed. Specifically, a computer graphic and statistical-based technique will be presented that enables timely and measurable image registration between radiological image space and the coordinate system of computer-driven surgical devices in the operating room. This technique may be utilized to maintain a surgeon's orientation and to quantitatively and graphically monitor the position of probes and instruments in the surgical field. Three-dimensional quantitative results of phantom testing will be presented. Correlation to and validation against stereotactic imaging calculations using the compass stereotactic system will also be discussed. These computer graphic/statistical-based techniques are applicable for evaluating the accuracy of any frameless stereotactic device including, but not limited to robotic arms, spark gap, LED and magnetic field digitizers.

Evaluation Studies as Topic↗

PubMed1998

Stereoscopic visualization of three-dimensional ultrasonic data applied to breast tumours.

OBJECTIVE: This paper presents a technique for stereoscopic visualization applied to three-dimensional (3D) ultrasonic breast data. METHODS: A motorized acquisition system has been designed to translate regularly a linear-phased array transducer, in order to provide a series of parallel echographic slices of the breast. During acquisition, the breast is compressed between a plane support and a plexiglass plate to avoid breast motion. A window in this plate provides access for ultrasonic exploration. From the series of cross-sectional scans, a 3D volume is formed by interpolation between the successive ultrasonic images. A stereoscopic computer-graphic method has been developed to visualize these 3D ultrasonic data. Two conical transparent projections of the volume are computed from two slightly different viewpoints. These two projections make up the stereoscopic pair. This pair is displayed on a stereoscopic monitor for the visualization of the 3D data with the depth dimension. RESULTS: The acquisition system and the method for computing the stereo-echograms were validated using an agar gel phantom. In vivo breast experiments were also performed. CONCLUSION: Visualization of stereo-echographic projections improves the perception of depth and shape of breast tumours.

Breast Diseases↗

PubMed2001

Virtual reality exposure therapy for Vietnam veterans with posttraumatic stress disorder.

BACKGROUND: Virtual reality (VR) integrates real-time computer graphics, body-tracking devices, visual displays, and other sensory input devices to immerse a participant in a computer-generated virtual environment that changes in a natural way with head and body motion. VR exposure (VRE) is proposed as an alternative to typical imaginal exposure treatment for Vietnam combat veterans with posttraumatic stress disorder (PTSD). METHOD: This report presents the results of an open clinical trial using VRE to treat Vietnam combat veterans who have DSM-IV PTSD. In 8 to 16 sessions, 10 male patients were exposed to 2 virtual environments: a virtual Huey helicopter flying over a virtual Vietnam and a clearing surrounded by jungle. RESULTS: Clinician-rated PTSD symptoms as measured by the Clinician Administered PTSD Scale, the primary outcome measure, at 6-month follow-up indicated an overall statistically significant reduction from baseline (p = .0021) in symptoms associated with specific reported traumatic experiences. All 8 participants interviewed at the 6-month follow-up reported reductions in PTSD symptoms ranging from 15% to 67%. Significant decreases were seen in all 3 symptom clusters (p < .02). Patient self-reported intrusion symptoms as measured by the Impact of Event Scale were significantly lower (p < .05) at 3 months than at baseline but not at 6 months, although there was a clear trend toward fewer intrusive thoughts and somewhat less avoidance. CONCLUSION: Virtual reality exposure therapy holds promise for treating PTSD in Vietnam veterans.

Follow-Up Studies↗

PubMed1990

Tri-meridional analysis using arbitrary meridians.

The evaluation of the sphero-cylindrical components of curvature or refraction from measurements taken along three distinct meridians has been solved for various sets of three fixed meridians. A constraint of those solutions has been that the meridians of measurement are necessarily predetermined, which introduces an unwelcome restriction in experimental or clinical applications of tri-meridional analysis. A new solution is presented (in three formats: analogue computer, graphical and algebraic), which enables any set of three meridians to be used for tri-meridional analysis. A computer program listing (in BASIC) is included.

Computers, Analog↗

PubMed1989

On the existence of limit cycles in motion field.

In this paper we show the existence of limit cycles in the vector field generated by the perspective projection on the image plane of the velocity field of a moving surface. The existence of limit cycles is proved with the Poincaré-Bendixon theorem, in the case of a rotating smooth non-planar surface and illustrated with computer graphics. The structural stability of the limit cycles is also discussed.

Computer Simulation↗

PubMed1995

Utilization of radioligands in schizophrenia research.

Interest in the role of monoaminergic mechanisms in schizophrenia has stimulated the development of specific radioligands that allow PET analysis of quantitative aspects of monoamine receptor subtypes in the living human brain. Clinical studies with such ligands have not consistently demonstrated specific alterations of the total populations of D1 and D2 dopamine receptors in the caudate putamen complex of drug-naive schizophrenic patients. However, recent studies using [11C]SCH 23390, a specific D1 dopamine receptor ligand, disclosed a highly significant reduction of ligand binding in pixel elements of the basal ganglia that normally contain high activity. This finding may be related to reduced D1 dopamine regulated transmission in subsets of neuronal pathways within the basal ganglia. D3, D4, and D5 receptor subtypes constitute minor fractions of the total number of dopamine receptors in the human brain. However, efforts to find selective ligands for D3 and D4 subtypes also show promise. Radioligands for monoamine receptors have also been used to follow drug effects on receptor subtypes in schizophrenic patients treated with different types of antipsychotic drugs. Such studies have allowed the analysis of relationships between occupancy of dopamine receptor subtypes and some clinical manifestations of drug treatment. Such studies with the selective D2 antagonist raclopride indicated quantitative relationships between the degree of D2 dopamine receptor occupancy in the basal ganglia and the extrapyramidal manifestations, as well as the antipsychotic action. Some of the currently available antipsychotic drugs also induced significant occupancy of D1 dopamine receptors. However, the selective D1 antagonist SCH 39166 in doses inducing a more than 70% occupancy of D1 dopamine receptors in the caudate putamen failed to induce an antipsychotic action. This indicates that, in contrast to D2 blockade, selective antagonism of D1-regulated pathways does not mediate antipsychotic action in schizophrenia. Some but not all antipsychotic drugs also induced high occupancy of neocortical 5HT2A receptors. Because selective 5HT2A antagonism does not appear to be an efficient treatment for schizophrenia, it seems most likely that 5HT2A receptors and, perhaps, D1 receptors act in concert to modify aspects of the mandatory D2 blockade to induce antipsychotic actions. Computer graphic methods for image analysis add new dimensions to brain imaging research, allowing three-dimensional visualization of receptor populations computed from molecular PET data. This will make possible further exploration of the detailed molecular compartmentalization of the human brain using radioligand binding.

Brain↗

PubMed1995

A desk top computer program for visualized statistical analysis of lesional images in intracerebral hemorrhage.

Statistically identified information on the relationships between the sites of lesions in intracerebral hemorrhage (ICH), risk factors such as a smoking or drinking habit, anamnesis, and biochemical data through blood tests will extend assistance to neuromedical clinicians on their daily clinical duties. It will provide them with a useful guide to determine the method of treatment. Also, it will be a basic research material for their clinical studies on diagnosis, progress, or prognosis in ICH. In order to obtain such statistics with the help of the computer, we need to have a computationally effective image database system. As is generally known, medical image data especially requires a great amount of storage; high-speed processing techniques are therefore also needed to deal with such data effectively. In addition, it is desired that we have outputs from the analysis edited with well-visualized effect, using 3D computer graphics, etc. These are why most existing image processing systems have been designed to work on comparatively large-scale computers. So far as we know, it is hard to find a practical and inexpensive personal computer-based application system for visualized statistical analysis of lesional images in ICH. We have developed a desk top computer-based program for statistical analysis of lesional image data of ICH. With this system, we can organize a medical image database that consists of the personal data of patients with ICH (sex, age, occupation, diagnosis, symptoms, part of physical disorder, etc.), risk factors, anamnesis (cerebral apoplexy, hypertension, hypotension, corpulence, diabetes, hyperlipidemia, atrial fibrillation, valvular endocarditis, etc.), biochemical data of blood, and lesional image data from CT or MRI. This system consists of the following components: 1) database management, 2) information retrieval (IR), 3) lesional image processing, 4) statistical analysis, and 5) prognostic prediction. The images are drawn manually on prescribed data sheets by tracing CT or MRI films and are read through the image scanner; then the compressed data of the digitized images is recorded in the database. Each recorded image data consists of the following two components: the frame image that corresponds to the contour of tissues of interest on the corresponding sliced section, and the actual image that corresponds to the lesion itself. In our system, these two images are separately stored and managed so that we can effectively perform subsequent image analysis. Other variables in the database (risk factors, anamnesis, etc.) are mainly used as search keys for making the aggregate of image data by the IR subsystem. In any aggregate, its elements, namely image data, have common medical background descriptions with the search keys. These aggregates can be used as input for the lesional image processing subsystem. With this subsystem, we can obtain the accumulated distribution of frequencies within a specified range of any sliced section, display planar color maps and profiles associated with the distribution, reconstruct it in 3D form, perform transformations of 3D images (zooming, enhancement, rotation, etc.), and test the significant difference of frequencies between any two different sites. We have been making practical use of this system to find the neurological relationship between the symptom (dysarthria, and paralysis of upper/lower limbs) and the site of lesion with cerebral infarction in pons. This study is quite important since the distributions of pyramidal tract related to the above symptom in pons are not well-known compared to those in cerebral cortex, internal capsule, or cerebral peduncle. With our system, we have obtained several findings expected to be helpful for this study. However, since this study is still in the initial phases, we will only present the outcome as a working example of our system. Our system was originally developed for analyzing lesional images with ICH. However, it could

Cerebral Hemorrhage↗

PubMed1989

Three-dimensional molecular distribution in single cells analysed using the digital imaging microscope.

Cellular changes in molecular distribution are believed to underly a wide range of cell functions. In order to investigate changes in molecular distribution in single cells utilizing fluorescent probes we have developed a digital imaging microscope. The system, consisting of both hardware and software, automatically acquires 3-D data sets consisting of optical sections and then processes such data to facilitate the analysis of molecular distribution in single cells. The first major step in processing reverses distortion introduced principally by the optics of the fluorescent microscope. Various procedures for accomplishing this task are compared and a method based on regularization theory is shown to give superior results for several different 3-D images. Following this step features of interest are automatically extracted from 3-D images utilizing an artificial 3-D visual system. This artificial visual system utilize a system of spatial filters to identify regional characteristics of images, the information obtained from these filters being used to identify and characterize clusters of molecules within the image. This information is then utilized to construct a 3-D graphical model of molecular distribution in single cells. Such models are displayed in 3-D and may further analysed utilizing interactive 3-D computer graphics. These methods are illustrated by results obtained regarding alpha-actinin distribution in single smooth muscle cells.

Actinin↗

PubMed1996

Virtual Reality Simulation of Gynecologic Laparoscopy

Realistic virtual simulation of gynecologic laparoscopy would permit the surgeon to practice any procedure, with any degree of pathology, at any time and as many times as necessary to achieve proficiency before attempting it in the operating room. Effective computer simulation requires accurate anatomy, realistic three-dimensional computer graphics, the ability to cut and deform tissue in response to instruments, and an appropriate hardware interface. The Visible Human Project from the National Library of Medicine has made available extremely accurate, three-dimensional, digital data that computer animation companies have begun to transform to three-dimensional graphic images. The problem of tissue deformation and movement is approached by a software package called TELEOS. Hardware consisting of two scissor-grip laparoscopic handles mounted on a sensor can interface with any simulation program to simulate a multiplicity of laparoscopic instruments. The next step will be to combine TELEOS with the three-dimensional anatomy data and configure it for gynecologic surgery.

Journal Article↗

PubMed1999

The effect of neodymium: YAG capsulotomy on contrast sensitivity and the evaluation of methods for its assessment.

OBJECTIVE: To determine the most appropriate method for measuring the effect on contrast sensitivity of neodymium:YAG (Nd:YAG) posterior capsulotomy for early posterior capsular opacification (PCO). DESIGN: Prospective comparison of five different methods for luminous contrast sensitivity testing in patients undergoing capsulotomy. PARTICIPANTS: Sixteen patients with PCO involving the visual axis and visual acuities of 20/40 or better were recruited sequentially. INTERVENTION: All patients were tested with each of the five tests before and after Nd:YAG capsulotomy. MAIN OUTCOME MEASURES: The contrast sensitivity function was measured with variable contrast sine wave gratings using the Vistech VCTS 6500, Mentor B-VAT-II and a computer graphics system. Peak contrast sensitivity at 3 cyc/deg was compared with two letter tests, the Pelli-Robson chart, and a computer that generated optotypes. RESULTS: Significant generalized improvement that was not frequency selective was measured over the entire contrast sensitivity function after capsulotomy. The five tests did not significantly differ (P > 0.05) in their measurement of peak contrast sensitivity (3 cyc/deg) improvement after capsulotomy. Letter-based tests showed better agreement and lower variance than gratings tests. Visual acuity and contrast sensitivity improvement were poorly correlated. CONCLUSIONS: This study shows that contrast sensitivity is adequately documented by a single measurement at 3 cyc/deg, is an informative supplement to visual acuity, and that little extra information is to be gained by measuring further spatial frequencies in eyes with PCO. Peak contrast sensitivity is best determined using a letter-based test.

Aged↗

PubMed1994

[Tridimensional radiation treatment planning].

The effectiveness of radiotherapy and the possibility that the patient will be cured are basically determined by the accuracy of the therapy planning and the treatment. The tumour with its environment is a three-dimensional (3D) phenomenon, and therefore 3D radiation treatment planning and performance are needed for adequate coverage of the target volume (tumour+safety zone). The prerequisities of the elaboration of the 3D radiotherapy planning were as follows: the availability of high-performance hardware, the establishment of interactive computer graphics, and the development and direct integration into the therapy planning process of the digitalized information derived from diagnostic imaging, and especially computer tomography. The introduction of 3D treatment planning will mean the modernization of the radiotherapy, the accuracy of which may permit more cures, i. e. more patients will recover their ability to work.

Dose-Response Relationship, Radiation↗

PubMed1978

Computer assisted unit data acquistion/reduction.

A computer system for unit data acquisition and reduction (CAUDAR) is presented. This system digitally processes uninterrupted, continuous unit data with attention to waveform detail. Several units in a multiunit field are recognized by evaluation of spike waveform and amplitude. High-speed computer graphics provides almost instantaneous figures of good quality for illustration. The system affords a great economy of the user's time because the computer performs all data processing.

Computers↗

PubMed1986

A multimodal system for reconstruction and quantification of neurologic structures.

The utility of computers and computer graphics as aids in the study of nervous system architecture is growing. However, modern histologic, immunocytologic and biochemical methods for revealing the underlying microarchitecture and macroarchitecture of the nervous system yield data formats requiring disparate computer acquisition, analysis and display approaches, capable of spanning many orders of magnitude of scale. This paper describes the Image Graphics Laboratory data acquisition, processing and display system, whose various components and programs may be used singly or in concert to enable definition of various tissue properties at different levels of resolution and integration. Examples are given of the system's use in light microscopic two-dimensional and three-dimensional reconstructions, autoradiographic reconstructions, reconstructions from projected images, reconstructions of impregnated cells (e.g., whole neurons) and peripheral nerve image analysis.

Animals↗

PubMed1984

A study of the interactions between residues in the C-terminal half of calmodulin by one and two-dimensional NMR methods and computer modelling.

Assignments of the six sets of aromatic ring protons and four high-field-shifted methyl group protons of the C-terminal fragment of calmodulin, residues 78-148, was achieved by a combination of one and two-dimensional NMR spectroscopic methods. A full spectral analysis of the aromatic region in terms of chemical shifts and scalar coupling constants was achieved and confirmed by spectral simulation. A three-dimensional structural model of the C-terminal fragment was constructed by interactive computer graphics techniques and combined with nuclear Overhauser enhancements to propose sequence assignments for all aromatic and high-field-shifted methyl groups. This computer-generated three-dimensional model was generally supported by the fact that it qualitatively accounted for many of the ring-current-shifted proton resonances and the intraresidue and interresidue nuclear Overhauser enhancements.

Animals↗

PubMed1984

Strain topography of human tendon and fascia.

Discretized surface strains for human tendon and fascia were photogrammetrically determined with high-speed cinematography and were displayed topographically using three-dimensional computer graphics. Substantial differences were found between estimates of tissue strain measured from grip motion versus discretized strain estimates from high-speed films. The computer-generated contour maps also provide a useful technique for analyzing the nonhomogeneity of tendon and fascial strains during high rate tests.

Adult↗

PubMed1981

Real-time color graphics in studies of molecular interactions.

Studies of the structures and interactions of large biological molecules require both coordinate data and three-dimensional visualization. Orthodox molecular models often bear a tenuous relationship to the coordinate data. In contrast, computer graphics requires that the display directly and accurately represent the data, and storage of modified configurations and recovery of original structures are simple. Software has been developed that allows real-time display of color line and surface displays of several interacting molecules, while quantitatively monitoring the stereochemistry.

Carboxypeptidases↗

PubMedDate not supplied

Mixing Apple microcomputer graphics for ultrasound scan measurement.

A modern microcomputer with high-resolution graphics can provide an inexpensive method for measurement on video images from a real-time ultrasound scanner. The problem which has to be overcome to allow the computer graphics to be superimposed on the ultrasound video image and permit subsequent analysis is that of synchronization. The video signals must be synchronized before they can be mixed, but neither microcomputers nor ultrasound scanners provide facilities for external synchronization of their video output. A mixer has been designed which uses a buffer memory and allows the graphics of an Apple II microcomputer to be synchronized and mixed with an external video image; we used a Hitachi EUB22 real-time ultrasound scanner. The resulting combination is a versatile instrument which permits a wide range of measurements on ultrasonic images.

Computers↗