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At least 235 records · Page 13Linked to original sources
PubMed1994

Computer-assisted 3D reconstruction of the terminal branches of the cerebral arteries. I. Anterior cerebral artery.

We present a three-dimensional anatomical computer model of the terminal branches of the anterior cerebral artery, acquired from equidistant serial anatomical slices of three brains. The reconstructions provide a clear picture from all angles of the complicated course of the terminal branches of the cerebral arteries, which can help to identify them on conventional and magnetic resonance angiography. Our rendition of the cerebral arteries can also be matched with CT, MR or PET images to indicate the areas of extension of individual branches, allowing neuromorphological and functional correlations.

Adult↗
PubMed1994

Computer-assisted 3D reconstruction of the terminal branches of the cerebral arteries. II. Middle cerebral artery.

We present a three-dimensional anatomical computer model of the terminal branches of the middle cerebral artery, acquired from equidistant serial anatomical slices of three brains. The reconstructions provide a clear picture from all angles of the complicated course of the terminal branches of the cerebral arteries, which can help to identify them on conventional angiography and magnetic resonance angiography. The arteries can also be matched with CT, MR or PET images to indicate the areas of extension of individual branches, allowing neuromorphological and functional correlations.

Adult↗
PubMedDate not supplied

Construction of parametric model of operator and workstation.

The purpose of development of a parametric model and the construction and formulation of the parametric model are described. To validate the parametric model, the distribution of the difference between the preferred and theoretical seat height settings of a number of office workers was evaluated from the standpoint of the static posture that does not change with time. The results of precise measurements made for an engineering workstation and an operator were also evaluated. Finally, the theoretical seat height settings with dynamic posture were evaluated. The validity of the parametric model was verified under the experimental conditions.

Algorithms↗
PubMed1997

A binocular fiberscope for presenting visual stimuli during fMRI.

A binocular pair of fiberscopes relays high-resolution images of CRT displays from an adjacent room to an observer lying in a scanner in functional Magnetic Resonance Imaging (fMRI) studies of visual function. We review the problems that must be overcome by any visual display for use in fMRI, present the specific solution we developed, and discuss its merits. Together, the fiberscope and CRT conveniently display accurately controlled high- and low-contrast wide-field images to an observer in an fMRI scanner.

Computer Terminals↗
PubMed1994

Visual design for the user interface, Part 2: Graphics in the interface.

Highly interactive multimedia electronic documents pose unique graphic information design problems. This paper is a discussion of some of the graphic design considerations that are unique to electronic documents, including the challenges of adapting existing graphic design skills to electronic documents that are displayed and read from computer screens.

Computer Graphics↗
PubMed1995

Preferred viewing distances for handheld and structurally fixed displays.

This research was conducted to define viewing distance characteristics of individuals engaged in ordinary reading tasks. Specific attention was directed to assessing the potential relationship between observed distance and individual resting point accommodation. Consistent, statistically significant differences were observed across variable handheld and structurally-fixed hardcopy display configuration conditions. Relationships between observed viewing distance and resting point accommodation were not apparent. These findings suggest that simple eye-to-display viewing distance is fundamentally different for handheld text presentations and for the same text presented in a configuration similar to that of a video display terminal.

Accommodation, Ocular↗
PubMed1997

Detection of interstitial lung abnormalities on picture archive and communication system video monitors.

The purpose of this study was to compare the detection of interstitial lung abnormalities on video display workstation monitors between radiologists experienced with video image interpretation and radiologists who lack this experience. Twenty-four patients with interstitial lung abnormalities documented by high-resolution computed tomography (HRCT) and lung biopsy, and 26 control patients with no history of pulmonary disease or a normal HRCT and normal chest radiographs were studied. Images were acquired using storage phosphor digital radiography and displayed on 1,640 x 2,048 pixel resolution video monitors. Five board-certified radiologists evaluated the images in a blinded and randomized manner by using a six-point presence of abnormality grading scale. Three radiologists were from 1 to 4 years out of residency and considered to be experienced workstation monitor readers with between 1 to 3 years of video monitor image interpretation. For the inexperienced readers, one radiologist had no prior experience with reading images from a video monitor and was direct out of residency, and the other radiologist had less than 4 months of intermittent exposure and was 1 year out of residency. Sensitivity and specificity were determined for individual readers. Positive predictive values, negative predictive values, accuracy, and receiver-operating curves were also generated. A comparison was made between experienced and inexperienced readers. For readers experienced with video monitor image interpretation, the sensitivity ranged from 87.5% to 92%, specificity from 69% to 92%, positive predictive value (PPV) from 73% to 87.5%, negative predictive value (NPV) from 87% to 90%, and accuracy from 80% to 88%. For inexperienced readers, these values were sensitivity 58%, specificity 50% to 65%, PPV 52% to 61%, NPV 56.5% to 63%, and accuracy 54% to 62%. Comparing image interpretation between experienced and inexperienced readers, there were statistically significant differences for sensitivity (P < .01), specificity (P < .01), PPV (P < .05), NPV (P < .05), accuracy (P < .05), and area under the receiver operator curve (Az) (P < .01). Within the respective experienced and inexperienced groups, no statistical significant differences were present. Our results show that digitally acquired chest radiographs displayed on high-resolution workstation monitors are adequate for the detection of interstitial lung abnormalities when the images are interpreted by radiologists experienced with video image interpretation. Radiologists inexperienced with video monitor image interpretation, however, cannot reliably interpret images for the detection of interstitial lung abnormalities.

Adult↗
PubMed1994

A method of measuring fingertip loading during keyboard use.

A single keycap on a standard alphanumeric computer keyboard was instrumented with a piezoelectric load cell and the fingertip motion was recorded with a high-speed video motion analysis system. Contact force histories between the fingertip and the keycap were recorded while four subjects typed a standard text for five minutes. Each keystroke force history is characterized by three distinct phases: (I) keyswitch compression, (II) finger impact and (III) fingertip pulp compression and release. Each keystroke force history contained two relative maxima, one in phase II and one in phase III. The subject mean peak forces ranged from 1.6 to 5.3 N and the subject mean peak fingertip velocities ranged from 0.3 to 0.7 m/s. Motion analyses and force measurements suggest a ballistic model of finger motion during typing.

Computer Terminals↗
PubMedDate not supplied

Assessment of commercial compression algorithms, of the lossy DCT and lossless types, applied to diagnostic digital image files.

The need for diagnostic image compression of the lossy or irreversible type has been declining due to the rapid increase in commercially available formatted hard disk capacity. It is estimated that the latter has increased about three orders of magnitude in the past 14 years while the size of diagnostic image files has, of course, remained constant. During the same period, despite claims for significantly improved performance by vendors, it seems that only small progress has been made in commercial lossless and lossy compression algorithms. There is still no consensus for lossy compression to a level acceptable for diagnosis. This is mostly considered to be around a ratio of 10:1. However, acceptable compression ratios depend heavily on the type of images processed and may be compared with the 3:1 ratio produced by lossless algorithms. This last value was shown to increase to more than 5.5:1 for gamma-camera images when corrected for the noise content of individual bit planes and for the display capabilities of computer monitors. Therefore, any possible benefits of lossy over lossless compression become questionable when the currently available hard disk capacity and network transmission speed are considered against the inevitable loss of information in the lossy type of compression.

Algorithms↗
PubMed1997

An optical system for measuring inclination and area of occlusal facets.

Occlusal facets are regarded as an individual record of occlusal contacts that result from various mandibular movements. Analysing characteristics of the facets is important for the functional assessment of the stomatognathic system. A new system which quantifies such characteristics optically has been developed. This system is composed of optical devices, a graphic image-processor, a set of stages for mounting and positioning the model and laser indicators of the measuring point. The system enables the inclination and area of each facet and its location to be measured and its processed image displayed on the graphic monitor.

Computer Graphics↗
PubMed1992

Obstacles encountered in the development of the low vision enhancement system.

The Johns Hopkins Wilmer Eye Institute and the NASA Stennis Space Center are collaborating on the development of a new high technology low vision aid called the Low Vision Enhancement System (LVES). The LVES consists of a binocular head-mounted video display system, video cameras mounted on the head-mounted display, and real-time video image processing in a system package that is battery powered and portable. Through a phased development approach, several generations of the LVES can be made available to the patient in a timely fashion. This paper describes the LVES project with major emphasis on technical problems encountered or anticipated during the development process.

Audiovisual Aids↗