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PubMed1977

[The application of the digital computer in vestibulometry (author's transl)].

All the interesting parameters of nystagmus-reactions during routine vestibular examination are calculated by a digital computer. The new parameters are plotted in a numerical and graphical way. This histogram figure their temporal distribution comparing reactions of both sides and give information about quantitative and qualitative criterions of the ENG. By correlation of parameters with each other and with further clinical findings their diagnostical value is investigated.

Computers↗
PubMed2001

A comparative study of computed digital absorptiometry and conventional dual-energy X-ray absorptiometry in postmenopausal women.

The aim of the study was to evaluate whether computed digital absorptiometry (CDA) of the hand might be a useful screening technique for identifying patients with postmenopausal osteoporosis and to compare the results of CDA with those of dual-energy X-ray absorptiometry (DXA) of the lumbar spine and femoral neck. We studied 230 postmenopausal women (mean age 58.4 + 7.9 years). For CDA, bone mineral density (BMD) was measured with an AccuDEXA Schick densitometer in the third middle phalanx of the nondominant hand. For DXA, BMD of the lumbar spine and upper femur was assessed using a DXA Hologic QDR-1000 densitometer. We did a comparative analysis (ANOVA) and linear correlation tests. Sensitivity and specificity of CDA and receiver operating characteristic (ROC) curves for the diagnosis of osteoporosis were calculated. The mean BMD with CDA was 0.445 +/- 0.084 (T-score: -1.27 +/- 1.29). The mean BMD (g/cm2) with DXA at the lumbar spine was 0.877 +/- 0.166 (T-score: -1.52 +/- 1.59) and 0.708 +/- 0.127 at the femoral neck (T-score: -1.12 +/- 1.25). BMD at the lumbar spine and femoral neck correlated positively with CDA of the hand (r = 0.66 and r = 0.65 respectively, p<0.001). When using as cut-off a T-score of -2.5, according to WHO criteria, 76 women (33%) had osteoporosis of the lumbar spine and/or femoral neck with DXA and 42 (18%) with CDA (p<0.001). The kappa score for osteoporosis was 0.33 for CDA versus spinal DXA and 0.35 for CDA versus femoral DXA. With the cut-off level used, sensitivity and specificity of CDA in detecting osteoporosis at the lumbar spine were 0.39 and 0.90, respectively; sensitivity and specificity of CDA in identifying osteoporosis at the femoral neck were 0.58 and 0.87, respectively. The positive predictive value of CDA for osteoporosis was 69% and the negative predictive value was 75%. The area under the ROC curve for osteoporosis was 0.822 +/- 0.028. We conclude that: (a) CDA assessment has a moderate correlation with BMD measured by DXA at the lumbar spine and femoral neck; (b) CDA has a low sensitivity for the diagnosis of osteoporosis compared with spinal and femoral DXA; and (c) predictive values for osteoporosis at both the lumbar spine and femoral neck are acceptable.

Absorptiometry, Photon↗
PubMed1975

A system for processing by digital computer spirograms acquired in field surveys.

Instrumentation and techniques are described for recording expiratory spirograms in the field and analysing them with a digital computer in the laboratory. A commercially available spirometer is modified, to give an oscillating electrical output signal which is recorded on a cassette tape recorder. The computer displays the spirogram, calculates the forced vital capacity, one-second forced expiratory volume, maximum mid-expiratory flow, and time to expire 25%, 50%, 75%, and 90% of the vital capacity.

Computers↗
PubMedDate not supplied

[Methods of input into a digital computer of low-frequency physiological data].

A procedure employed for input of low-frequency physiological information coming via several channels in a digital computer, model M-220A has been worked out. The operations are effected through the application of standard equipment with the use of routine communication channels to the computer. Particular attention is attached to the storage of the input information in the permanent memory of the machine for further synchronous analysis of physiological indices. The procedure may find use in analyzing materials covering a wide range of medico-biological experiments.

Computers↗
PubMed1983

The circumferential length of the internal elastic membrane measured by computer digitizer morphometry, and its relation to in vivo aorta diameter.

The circumference of the internal elastic membrane of rabbit aorta has been measured by means of computer digitizer morphometry. Measurements were made on sections cut at 90 degrees to the longitudinal axis of the vessel. These measurements were compared with calculated values of a luminal circumference based on in vivo measurements of the external diameter and vessel wall thickness measured on the sections prepared. It is found that the lengths of the internal elastic membranes measured are significantly greater than the calculated values. Thus the internal elastic membranes must be thrown into folds in vivo. The possible function of the folds is considered.

Animals↗
PubMed1992

Cardiovascular simulation using a multiple modeling method on a digital computer--simulation of interaction between the cardiovascular system and angiotensin II.

A cardiovascular system model that simulates interactive responses to drugs has been developed on a small digital computer. The overall model basically consists of three models. The first is a momentum transport model that represents relations between blood pressure and flow in the cardiovascular system. In this model, the cardiovascular system is divided into 14 components and modeled by using equivalent electrical circuits. The second is a mass transport model comprising 14 compartments corresponding to the respective components of the cardiovascular system. This model represents the distribution of the administered drug in the various cardiovascular components. The third is an interaction model that represents the relationships between the momentum and mass transport models. This model causes variations in the resistance and capacitance parameters of the momentum transport model as a function of the current drug concentrations in the appropriate compartments of the mass transport model. The capacitances representing the ventricles are varied in a time-dependent fashion to simulate the beat of the heart. Simulation is performed by using the Euler method to solve a system of 28 ordinary differential equations governing the momentum and mass transport models on a 32-bit microcomputer, a Macintosh II. The model was assessed by performing two demonstrations of the cardiovascular response to the vasopressor angiotensin II (AT II). They first examined the interaction between the cardiovascular system and AT II. The effect of AT II on the cardiovascular system was incorporated into the interaction model. Administration of AT II as a constant infusion (200 micrograms/hr) resulted in an elevation of mean arterial pressure from approximately 100 to 150 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1978

The relationship between attachment height and attachment area of teeth using a digitizer and a digital computer.

Nine lower first bicuspid teeth were mounted in blocks of plastic and their roots were serially sectioned and photographed. Data from the photographs were compiled by a digitizer and a digital computer, which calculated the cumulative root surface area for each millimeter of root height. From these data, three variables, which relate root surface area to root height, were calculated. It was found that if one-half of the height of attachment to the root were lost due to periodontal disease, a mean of 61.5% of the actual attachment area to the root is lost. If a mean of 5.72 mm of root attachment height is lost, or if a mean of 60.6% of the same root height remains, only one-half of the total root attachment area remains to provide tooth support.

Bicuspid↗
PubMed1984

The digital computer: the role of functional imaging in radiology.

Over the past decade there has been an increase in the use of functional imaging. This is mainly because of the recent introduction of the digital computer, which is capable of processing measured data into images that are related to a physiological process or the function of an organ. This is a departure from the more traditional images that are mostly based on anatomical detail. The radiologist needs to become familiar with these new imaging concepts, since a continued growth in their use is inevitable.

Computers↗
PubMed1990

[Digital computer arthrometry of the upper ankle joint using a personal computer. A new procedure].

The digital computerarthrometry (DCAM) was developed as a very cost-effective device to calculate the pathologic angles of injured joints. The joint's data are captured by a frame grabber-board installed in a personal computer after takeover from the X-rays by a video camera. Measurements are performed using a commercially available software package which displays the X-ray-photograph on a separate screen besides the one used to manipulate the computer. With this system the calculations of angles and distances of the injured joints are performed with considerably higher precision as it could be done before. As a further possibility bone density measurements may be done from the X-rays as it had been tried to before computers could be used. Our first results seem to present our system as an alternative to the costly workstations, that had to be used until now.

Ankle Joint↗
PubMed2000

Misinterpretation of human electrogastrograms related to inappropriate data conditioning and acquisition using digital computers.

Despite the fact that digital techniques for data acquisition and processing were widely used in electrogastrographic (EGG) research during the last decade, inappropriate signal conditioning and digitization are still potential pitfalls threatening the reliability of the experiments. The aim of this paper was to review: (1) the importance of the antialiasing low-pass filtering for reducing recording artifacts and interferences, (2) the advantages brought by the proper choice of filter cutoff frequency and the slope for the decrement of the minimal required sampling frequency, (3) the impact of incorrectly selected sampling frequency on data interpretations, with particular attention to the percent distribution ranges, and (4) the "leakage effect" related to the finite number of samples processed simultaneously in frequency domain representation of the recordings. A model of electrogastrographic (EGG) recording was mixed with a model of electrocardiographic (ECG) artifact. The resulting finite-duration signal was low-pass filtered and then digitized with a sampling frequency of 1 Hz. The cutoff frequency of the first-order low-pass filter was altered from 0.5 to 0.1 Hz. Amplitude frequency spectra of the digitized recordings were investigated. An example with a real human electrogastrogram in which an ECG artifact was present confirmed the simulation results. When a first-order anti-aliasing filter is utilized at least a fivefold difference between the filter cutoff frequency and the sampling frequency is recommended for compliance with the Nyquist theorem of digitization. Leakage effects associated with the finite-time duration of the recordings and the use of the discrete Fourier transform should be considered when frequency domain analysis is performed. Misinterpretation of the "bradygastric" and "tachygastric" ranges in the percent distribution of EGG frequency components is possible if inappropriate signal conditioning and digitization are employed.

Artifacts↗
PubMed1978

Studies of skeletal tracer kinetics. I. Digital-computer solution of a five-compartment model of [18F] fluoride kinetics in humans.

We have developed a new model of short-term fluoride kinetics in humans and have solved the model on a digital computer using the SAAM-25 program. The solution accords well with available data. About 60% of intravenously administered [18F] fluoride is taken up by bone. Evaluation of the rate constants of tracer egress from blood indicates that about 17% of the cardiac output is distributed to the skeleton. When the model was perturbed to simulate changes in systemic or skeletal blood flow, we found that the system behaves in a nonlinear manner; even a five-fold increase in systemic or skeletal blood flow did not appreciably increase the amount of fluoride taken up by bone 1--2 hr later, the time when scans are usually made. A simulated increase in bone extraction rate, however, had a marked effect on bone-fluoride uptake. These findings suggest an important homeostatic role for bone in the regulation of blood calcium concentration and have considerable bearing on the interpretation of bone scans.

Bone and Bones↗
PubMed1975

Reconstruction of the Fresnel-coded gamma camera images by digital computer.

An algorithm for the digital reconstruction of the Fresnel-coded gamma camera image consists of the spatial Fourier transform of the hologram after applying a quadratic phase shift. Background subtraction is implemented by use of positive and negative zone plates. Tomographic planes are reconstructed in 27 sec from a single zone-plate shadow image by successively varying a parameter in the reconstruction algorithm on a small computer system.

Diagnosis, Computer-Assisted↗
PubMed1997

Precision and accuracy of computed digital absorptiometry for assessment of bone density of the hand.

Widespread osteoporosis testing and diagnosis are currently limited due to the high capital cost and reduced portability of many existing bone densitometry techniques. In this study we evaluated an inexpensive, low radiation, X-ray-based technique for assessing bone density of the middle phalanx. The technique, termed computed digital absorptiometry (CDA), is similar to radiographic absorptiometry (RA), using a single-energy X-ray source, an aluminum alloy step-wedge, and a charge-coupled device (CCD) detector system to automatically compute bone mineral content (BMC, g) and bone mineral density (BMD, g/cm2) in the middle phalanx of the third finger. The potential advantage of CDA over current RA techniques is that by using a filmless detector system, no off-site processing of radiographs is required and bone density results are obtained immediately after the test. Using human cadaveric specimens we determined the accuracy and short-term precision of CDA as well as its correlation with other hand and forearm bone densitometry methods. We obtained 26 cadaveric forearms (50% female, mean age 78 years, range 52-96 years). BMC and BMD of the middle phalanx of the third finger were determined using CDA and using RA. We assessed forearm BMC and BMD using single-energy and dualenergy X-ray absorptiometry (SXA and DXA). Precision of CDA was assessed by measuring ten of the specimens five times each with repositioning between measurements. Finally, the middle phalanx was dissected and incinerated to determine ash weight. BMC estimates from CDA and from RA were strongly correlated with ash weight (r = 0.89, p < 0.001 and r = 0.93, p < 0.001, respectively). The mean coefficients of variation using CDA were 1.36% and 0.70% for phalanx BMC and BMD, respectively. BMC and BMD measured by CDA were strongly correlated with hand and forearm bone mineral measurements performed by SXA, DXA and RA (r = 0.74-0.91). These results indicate that CDA accurately and precisely predicts BMC of the middle phalanx. Thus, with further clinical verification, this technique may prove to be a useful tool for the widespread testing and assessment of osteoporotic fracture risk.

Absorptiometry, Photon↗
PubMed1975

The use of a digital computer for the on-line real-time assessment of neuromuscular blockade in anaesthetized man.

A computer program written mainly in a high level language (ALGOL), but with the sampling routine and certain calculations written in assembly language (SIR), has been developed to assess neuromuscular blockade in anaesthetized man by means of an Elliott 903 digital computer. The program allows the on-line real-time analysis of a range of variables including twitch height, maximum slope of twitch and twitch pulse widths, peak height of tetanic contraction, end-height of tetanic contraction, the tetanic tension ratio and the percentage tetanic transmission. The program has been used to investigate the pattern of action of neuromuscular blocking drugs and has particular value in the study of the pharmacokinetic action of these drugs.

Computers↗
PubMed1976

Digital computer processing of brain scans using principal components.

Most of the scan processing methods used to date are unable to distinguish between normal and abnormal features. This paper describes a method of constructing a particular orthogonal transform from a set of normal images, the method of principal components, which may be used selectively to filter out normal features, leaving behind abnormal features. The method has been applied to brain scans and has been implemented on a small digital computer system with magnetic disc.

Brain Diseases↗
PubMed1964

DIGITAL COMPUTERS IN THE BIOLOGICAL LABORATORY. COMPUTER PROCESSING OF DATA DURING EXPERIMENTS FACILITATES BIOLOGICAL RESEARCH.

The use of digital techniques in the biological laboratory is relatively recent (22). At present, computer equipment is extremely expensive by contrast with conventional electronic equipment. However, the costs are decreasing, and these techniques are rapidly becoming more accessible as well as more powerful. Improvement in the fabrication, size, and compactness of solid-state devices promises rapid progress in computer technology of interest to the biologist. Through the use of integrated circuits it will be possible to make general-purpose computers no larger than a laboratory oscilloscope, as compared with the present desk-size console with auxiliary cabinets. Within a decade the speed of computation will increase by an order of magnitude, and the costs will decrease significantly. Moreover, it seems likely that the parts of a computer and the laboratory "interface" will become available as modular units. An experimenter will then be able to assemble the components necessary for a particular application and change them as required. At present, one has to modify commercial equipment for the nonstandard, biological uses. However, with modular building blocks of relatively small size and more reasonable cost the digital computer may become as familiar a laboratory tool tomorrow as the cathode-ray oscilloscope or the spectrophotometer is today.

Biology↗