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Computer graphics offers an unprecedented opportunity to probe new and old ideas in vision testing, without going to the expense of building dedicated equipment. However, the large variety of computer hardware is bewildering and only occasionally can commercial software tools be used. This mini review of the basic principles of computer graphics on personal computers is intended to help the newcomer to the field.
Computer graphic reconstructions of the prostate were made in both the transverse (axial) and longitudinal (sagittal) planes at different levels on the basis of the normal anatomic model of McNeal. Additional images then were created to give a picture of what the ultrasonogram should look like at each level, and these were compared with actual ultrasonograms of the normal prostate. A precise yet simple terminology is suggested for prostate ultrasonographic descriptions.
The authors present in their paper the possibilities of the application of computer graphics and computer animation for visualization of the electric heart field (EHF). They describe the construction of three-dimensional potential maps by the methods of interpolation, perspective projection, hidden line elimination and text generation. They also present a method for making of animation films showing the electric activity of the heart by using 80 three-dimensional potential maps recorded at different intervals over the entire cardiac cycle.
Computer vision (CV), a computerized method to analyze digital images (e.g., CT scans), and computer graphics (CG), a set of computer programs for displaying two, three- or four-dimensional data, are recent computer techniques which are appropriate to assist functional stereotactic surgery. CV and CG are useful for the evaluation of spatial relations between anatomical structures and the sites of spontaneous neuronal noise or of electrophysiological stimulation data gathered during stereotactic interventions for movement disorders. CV and CG can be employed for stereotactic operation planning, during the operation for target point evaluation and for further postoperative data analysis.
This report describes the appearance of maxillofacial squamous cell carcinoma in multiplanar (MPR) and three-dimensional (3D) images reconstructed from spiral CT using computer graphics and the importance of the computer software tools in permitting better visualization of the lesion. Two oral and maxillofacial radiologists and one neuroradiologist analysed the images. The usefulness of interactive reconstruction in the diagnosis, surgical planning and treatment evaluation, especially in the localization of the extent of these maxillofacial tumors, was demonstrated. Spiral CT-based computer graphics for displaying MPR and 3D images are an important adjunct in the evaluation of squamous cell carcinoma.
Stereophotogrammetry is an attractive technique for mapping changes in facial form and contour following surgery. The need for trained personnel, however, has prevented the technique from gaining wide use. We report the development of a stereophotogrammetric system in combination with an inter-graphics computer system which overcomes this and other limitations. An interactive computer graphics system is used to record, present and manipulate the three-dimensional data obtained from a digitized stereophotogrammetric picture. The system also permits measurement of morphological changes following surgery as well as volume changes and has the potential for use in indicating the order in which multistage procedures should be undertaken and the time delay before such surgeries.
Computer graphics using a personal computer were introduced to demonstrate the three-dimensional architecture of cutaneous arteries of the back in humans: the direct cutaneous artery of the circumflex scapular artery and the perforating cutaneous branches and musculocutaneous perforators of the superficial cervical, posterior intercostal, and thoracodorsal arteries. The entire thickness of the skin and underlying subcutaneous tissue over the deep fascia was obtained from five fresh cadavers injected systemically with lead oxide-gelatin mixture, and the integument was divided into the three layers; the skin, superficial adipofascial layer with the superficial fascia, and the deep adipofascial layer. Computer graphic reconstruction of the cutaneous arteries was performed using data based on angiograms of the three layers. The computer graphic depictions demonstrated in which layer cutaneous arteries branched and how the vessels were running in each layer by displaying each layer in different colors: red, yellow, and blue. Knowledge of the three-dimensional structure and architecture of the cutaneous arteries will aid in the development of flaps that use a portion of the skin and subcutaneous adipofascial tissue.
A computer graphics system has been used to fit a putative sequence to an electron density map of a sea snake neurotoxic protein at 2.2 A resolution. The complete sequence of this small protein could be determined from the map with very little ambiguity. In two places probable errors in the published chemical sequence were detected. This is the first instance in which a complete three-dimensional structure was solved with the use of computer graphics alone, without the construction of a physical model.
An interactive graphic computer program, called FLOWMAP, is used to examine the referral patterns of cancer patients in western Washington between 1974 and 1978. FLOWMAP allows one to produce several types of maps from origin-destination data easily and inexpensively. Several maps show some of the significant geographic components of the referral of more than 7000 cancer patients among 13 counties over a 5-year period. It is shown that cancer care has become more decentralized during this period. Nine other possible applications of FLOWMAP to issues of concern regarding the delivery of health care are described. Maps produced by FLOWMAP can be expected to cost 1/30 to 1/50 of the cost of comparable manual methods. An Appendix gives some technical detail regarding the use of FLOWMAP and its data requirements.
This paper describes the appearance of three cases of maxillofacial fibrosarcoma in multiplanar (MPR) and three-dimensional reconstructed computed tomography (3DCT). The images were analysed by two oral and maxillofacial radiologists and one neuroradiologist. All of the cases clearly demonstrated the usefulness of the interactive MPR and 3DCT in the diagnosis and evaluation of the extent of these maxillofacial tumors.
Interactive computer graphics have been used to construct a three-dimensional model of casiragua insulin assuming a tertiary structural homology with that of porcine insulin. The hydrophobic core of the molecule is conserved, but the hydrophobic surfaces involved in formation of dimers and hexamers in porcine insulin are more hydrophilic and contain charged residues. These observations are consistent with a close similarity of the far ultra violet circular dichroism of casiragua insulin and porcine insulin, and with the inability of casiragua insulin to self-associate. The low receptor-binding potency appears to result mainly from the substitution of B26-tyrosine by an arginine.
The efficacy of a neurosurgical navigation system using three-dimensional composite computer graphics (CGs) of magnetic resonance (MR) and computed tomography (CT) images was evaluated in skull base surgery. Three-point transformation was used for integration of MR and CT images. MR and CT image data were obtained with three skin markers placed on the patient's scalp. Volume-rendering manipulations of the data produced three-dimensional CGs of the scalp, brain, and lesions from the MR images, and the scalp and skull from the CT. Composite CGs of the scalp, skull, brain, and lesion were created by registering the three markers on the three-dimensional rendered scalp images obtained from MR imaging and CT in the system. This system was used for 14 patients with skull base lesions. Three-point transformation using three-dimensional CGs was easily performed for multimodal registration. Simulation of surgical procedures on composite CGs aided in comprehension of the skull base anatomy and selection of the optimal approaches. Intraoperative navigation aided in determination of actual spatial position in the skull base and the optimal trajectory to the tumor during surgical procedures.
A description of computer graphics of a multidimensional model that is used with computer-aided diagnosis or prognosis is presented. The model is discussed and computer graphics of the model are developed. The computer graphics are suitable as visual supplements for presenting the computer-aided diagnostic model to individuals who may be inexperienced in multivariate statistics.
Rules are outlined in order to construct graphically a computer model that deals with cell growth, multiplication and differentiation. The process starts with a multicoloured stem cell and the end product will be differentiated cells represented by different colours. Various biological processes and neoplastic transformation can also be simulated. Based on the idea that the model corresponds to real events, predictions are made about the possible results of future experiments.
Multidimensional computer graphics are demonstrated in two medical systems applications in this paper. First, multidimensional computer graphics are utilized for descriptive purposes to show the differences among 10 physician specialty groups for multivariate data available at admission to medical school. Second, multidimensional computer graphics are demonstrated as a method that can be used for screening school applicants. The novel method utilized to represent multivariate data requires the plotting of a face. Each feature of a face--for example, face height or ear diameter-can be utilized to represent a different dimension of multivariate data. Each face then represents a vector whose elements are the mean values of multiple variables, or it represents a multivariate observation.
This paper describes the use of three-dimensional computer graphics to display structures visible in computerized tomography (CT) scans and to accurately determine optimum stereotaxic probe placement relative to those structures. A prototype Lucite stereotaxic frame designed for use in CT body scanners was fitted with a phantom consisting of small Lucite spheres representing intracranial tumors with diameters of 6 to 19 mm. A series of CT scans was obtained of the frame and phantom together. Edge outlines of the spheres were extracted from each scan in the series. A three-dimensional visual representation of the spheres was obtained by displaying their outlines from all CT scans. A superimposed visual simulation of the stereotaxic frame was adjusted interactively using several analog dials in order to simulate trajectory choice and probe depth before actual surgery. The frame settings and probe depth calculated by the graphical computer were then applied to the actual prototype frame in order to assess the accuracy of this combined CT-computer graphics approach to stereotaxic localization. The results of 22 such experiments and the implications for future clinical use of this new and precise localization technique are discussed.
A computer-aided graphical analysis system is presented which can be used to quantify several types of information from micrographs of cross-sectioned peripheral nerves. A simple input consisting of eight points, corresponding to two diameters of each axon and two for each axon plus myelin, is used to compute statistical and numerical estimates of these diameters, the myelin thickness being expressed as a function of axon diameter, and both the spatial position and distribution of nerve fibres within the bundle. The computer programs presented and summarized here describe the procedure for digitizing the input data and the subsequent computations for editing and analysis. The general applicability of this approach for automated analyses of other anatomical areas is also presented.
Computer graphics is being employed at the NASA Johnson Space Center as a tool to perform rapid, efficient and economical analyses for man-machine integration, flight operations development and systems engineering. The Operator Station Design System (OSDS), a computer-based facility featuring a highly flexible and versatile interactive software package, PLAID, is described. This unique evaluation tool, with its expanding data base of Space Shuttle elements, various payloads, experiments, crew equipment and man models, supports a multitude of technical evaluations, including spacecraft and workstation layout, definition of astronaut visual access, flight techniques development, cargo integration and crew training. As OSDS is being applied to the Space Shuttle, Orbiter payloads (including the European Space Agency's Spacelab) and future space vehicles and stations, astronaut and systems safety are being enhanced. Typical OSDS examples are presented. By performing physical and operational evaluations during early conceptual phases. supporting systems verification for flight readiness, and applying its capabilities to real-time mission support, the OSDS provides the wherewithal to satisfy a growing need of the current and future space programs for efficient, economical analyses.