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At least 235 records · Page 13Linked to original sources
PubMed2001

Using computer graphics to preserve function in resection of malignant melanoma of the foot.

The increasing incidence of malignant melanoma challenges physicians to find innovative ways to preserve function and appearance in affected areas that require partial resection. We carefully planned the resection of a malignant lesion between the third and fourth toes of a 77-year-old man with the aid of computer technology. The subsequent excision of the third, fourth, and fifth digits was executed such that the new metatarsal arc formed would approximate the dimensions of the optimal hyperbola, thereby minimizing gait disturbance.

Aged↗
PubMed1987

Interactive computer graphic image analysis for functional neurosurgery.

This study deals with the use of microcomputer graphic analysis of preoperative magnetic resonance imaging (MRI) scans in functional neurosurgical procedures. Three patients (2 treated for thalamotomy and 1 for thalamic stimulation) had preadmission MRI scans which delineated the classic internal landmarks used in functional neurosurgery. These data were then manipulated and stored using a microcomputer-based graphic analysis system. Intraoperative pattern matching of preadmission graphics with the intraoperative skull X-rays allowed determination of the planned target in the x, y and z coordinates. The accuracy of the graphics FM-PC and AC-PC points was confirmed with the use of ventriculography, stimulation, and postoperative MRI scans. This simple, inexpensive method obviates the need for ventriculography, sedation, intraoperative MRI with a scan-compatible frame, and has the accuracy necessary for functional procedures.

Aged↗
PubMed1989

Morphology of fibroblasts in collagen gels: a study using 400 keV electron microscopy and computer graphics.

We have used 400 kilovolt intermediate voltage electron microscopy (IVEM) to examine thick sections of fibroblasts cultured in collagen gels. In these 3D collagen lattices, the long, narrow pseudopodial extensions that extend out and make contact with the collagen matrix exhibit a complex topography not seen in the processes put out by cells moving on planar substrata. For this reason, sections 1 to 2 microns thick that enclose a whole cell process are more informative of the overall morphology of the interaction between cells and the collagen than are thin sections. To aid the discrimination of topography of cell processes in stereo views of micrographs, some cells were labeled with antibodies and protein A-colloidal gold conjugates. The gold particles provided clear 3D reference points for computer-aided reconstructions of membrane topography from tilt series of IVEM images. Our results confirm that cells that move through collagen lattices lack the well-spread morphology of their counterparts moving on glass. They are generally rather spindly with several long branching anterior pseudopodia. We found that the cell bodies and major pseudopodial processes were cylindrical, as one might expect of cells in a 3D environment, but at the leading edge of advancing pseudopodia there are small flat extensions similar to those seen in cells on glass. This similarity suggests that the lamellipodium is a basic type of protrusive structure used by fibroblasts during locomotion on all types of substratum. The flattened shape of lamellipodia may be part of the mechanism by which cells sense the orientation of fibrillar extracellular matrices during embryonic morphogenesis.

Animals↗
PubMed1997

Virtual reality in medicine-computer graphics and interaction techniques.

This paper describes several new visualization and interaction techniques that enable the use of virtual environments for routine medical purposes. A new volume-rendering method supports shaded and transparent visualization of medical image sequences in real-time with an interactive threshold definition. Based on these rendering algorithms two complementary segmentation approaches offer an intuitive assistance for a wide range of requirements in diagnosis and therapy planning. In addition, a hierarchical data representation for geometric surface descriptions guarantees an optimal use of available hardware resources and prevents inaccurate visualization. The combination of the presented techniques empowers the improved human-machine interface of virtual reality to support every interactive task in medical three-dimensional (3-D) image processing, from visualization of unsegmented data volumes up to the simulation of surgical procedures.

Algorithms↗
PubMed1988

Computer graphic analysis of antigenic sites on the insulin molecule.

Antigenic sites on a protein have been predicted by the measurement of hydrophilicity values. We have compared this approach to the use of atomic temp factors to predict the antigenic sites on insulin. These predictions were based upon computer assisted analysis of X-ray crystallography data. The results demonstrate that the hydrophilic sites A6, B19, B23, B24, and B26 are not on the surface of the molecule and therefore are not potential antigenic determinants. Thus, hydrophilicity values alone are not sufficient to predict antigenic sites. In contrast, atomic temp factors were more predictive of antigenicity. These findings may explain why anti-insulin antibodies are less likely to develop against certain hydrophilic sites.

Animals↗
PubMed1996

[Evaluation of a computer graphic representation of echo-Doppler (Echotrace) in the assessment of atherosclerosis of the legs].

The problems generally encountered in interpreting written reports of echo-Doppler examinations led us to develop a graphic software system to visualize the vascular network: Echotrace. The objective of the present work was to evaluate the reliability of Echotrace in patients with atherosclerosis of the lower limbs using arteriography as the standard for assessing sonographic findings. This prospective study was conducted in 29 consecutive patients. Nineteen strategic sites of the arterial network were investigated with duplex-scan and arteriography: lesions scores were attributed for each examination and data for a given site were compared. On the 551 sites compared, we found 26 disagreements including 23 concerning lesion quantification and 3 on localizations. There were also 21 minor disagreements with a single variation in the pathology score. The statistical comparisons could not be made on these scores so the results were compared with the arteriography data on the basis of therapeutic decision taking into account all the arterial lesions and the patient's general status. We observed a perfect agreement between the two imaging techniques in 12 patients, one disagreement which would not change the treatment in 15 patients and, in 2 patients, a disagreement which would modify treatment. This study demonstrated that graphic visualization of arterial lesions with Echotrace is a reliable, easy-to-interpret method.

Adult↗
PubMed1992

Digital imaging, image processing, and three-dimensional computer graphics for radiology.

The acquisition of medical images and their display, manipulation, and applications have advanced significantly in the recent past. MR imaging using ultrafast echo planar and fast gradient-echo techniques have expanded application in cardiovascular studies, as well as in the brain and spinal cord. Spiral CT has the potential to revolutionize a well-established modality, subject to several important limitations. The postprocessing of medical sectional images from MR imaging, CT, ultrasound, positron emission tomography, and single-photon emission CT has rapidly grown in importance. We have seen the emergence of renewed and expanded applications of these images, suitably processed, in directing planning and performance of therapeutic procedures on patients through stereotactic techniques, intravascular ultrasound, robot surgery, and integrated displays. This more central role of three-dimensional imaging to medical care is new and will continue to grow. Research applications have recently appeared in neuromorphometry, multimodality registration, functional neuroimaging, quantitative coronary angiography, and saturation MR techniques for myocardial tissue tagging.

Computer Graphics↗
PubMed1989

[Synthesis of computer graphic calculated high-anti-fixed pyrimidine nucleoside analogs with potential virostatic and antineoplastic action].

Novel C-5 substituted 6,2'-anhydrouridines 5a-e are synthesized from the hitherto unknown monosubstituted ribofuranosylbarbituric acid derivatives 4a-e. These molecules are high-anti-fixed by a 6,2'-linkage and were assumed to show antiviral and antineoplastic effects. In cell culture test systems, however, none of these biological activities could be detected up to now.

Antineoplastic Agents↗