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At least 883 records · Page 49Linked to original sources
PubMed1977

[Nystagmus analysis by computer (author's transl)].

Automatic quantitative nystagmus analysis by means of a digital computer primarily gives a lot of data. Analysis then means reducing this amount of numerical data to a few relevant results. Because the diagnostic importance is not known yet for all available nystagmus parameters, this implies the risk of losing essential informations. Therefore, limitations of the number of parameters as well as of the duration of the investigated intervals by the method of analysis have to be avoided. This then allows studying the diagnostic value of new parameters (e.g. of the fast components) or the time course of reaction intensity. From this point of view a method of quantitative nystagmus analysis is described.

Computers↗
PubMed1987

Gallium-67 lung index computerization in interstitial pneumonitis.

To improve ease of use, precision, and reduce interobserver variability of the 67Ga lung index, we developed and tested a computer method that yields similar numeric values and uses previous indexing principles, except that the computer matrix unit is the fractional area assessed. Patients were referred for suspected interstitial lung disease. Fifty-three image studies were available for both manual and computer indexing. Linear regression analysis gave a correlation of 0.884. Decision matrix analysis of 58 different nonimmunosuppressed patients resulted in 93% sensitivity and 76% specificity. Receiver operating characteristic curve analysis showed that the ideal index cutoff was 50. Because there is tighter control over 67Ga uptake intensity and spatial distribution assessment, the computerized 67Ga index appears to perform better than the manual analysis.

Gallium Radioisotopes↗
PubMed1979

[Objectivation of tremor and motion disorders via computerisation (author's transl)].

The quantitative analysis of motion disorders of the upper extremities can be performed by means of a joystick connected with a minicomputer. Therefore a random squarewave curve is drawn on a computer display and the patient must follow it with the joystick. The deviation of the two curves are recorded, analysed and documented numerically and graphically.

Diagnosis, Computer-Assisted↗
PubMed1984

[Computer-assisted findings on protein electrophoresis on cellulose acetate film].

Until a short time ago efficient computer assisted reporting of electrophoretograms was not possible owing to the lack of appropriate technology. By integrating a fully mechanized electrophoresis system into the laboratory data processing system of a centralized institute of clinical chemistry, the separation and the interpretation of results can be performed for 300 samples per day. The interpretation is based upon available patient data (specified clinical diagnoses, previous results), calculated fractions and analysis of the electrophoretic curve in the area of albumin and the beta- and gamma-globulin fraction. In this way it is possible to classify hereditary bisalbuminaemias and to detect transient bisalbuminaemias and monoclonal gammopathies. Diagnostic indications of specific dysproteinaemias and defect proteinaemias are printed on the report form if individual serum protein fractions and the total protein content are changed specifically. The results of the different electrophoretic fractions, the total protein and a set of possible alterations of the curve are numerically coded according to the scaled biochemical ranges in five definite sections or to a decision matrix (alteration 'given' or 'not given'), respectively. The composed 'result patterns' are matched with preassigned 'reference patterns' stored in the computer file. The procedure is efficient and adaptable to other areas of analysis.

Albumins↗
PubMed1983

[Correlations between EEG (FFT) and the degree of consciousness in patients in the early post-traumatic phase].

In 73 comatose patients after cerebral trauma a computer-assisted study was done prospectively in relation to the clinical findings, the course, morbidity, and mortality as well as computer analysed EEG. The patients were examined at the 3rd, 6th, and 9 th day after trauma. The state of consciousness was scaled in 10 points and correlated to the numerous EEG results (spectral analysis and power in the delta-, sigma-, alpha-, and beta-range). As well it shows, the alpha-band gives the best correlation to the clinical findings and permit a certain prognosis.

Adolescent↗
PubMed1995

Neurophysiologic assessment in the management of spinal dysraphism.

Neurophysiologic techniques provide a valuable addition to the armamentarium of tools for the evaluation of sensory and motor function in the pediatric spinal cord. These techniques include median, radial, and ulnar nerve evoked potentials from the upper extremity; common peroneal and tibial nerve evoked potentials from the lower extremity; dermatomal potentials; and compound muscle action potentials and compound nerve action potentials. The techniques that evaluate the sensory system have been used extensively and effectively as research tools, as adjuncts to diagnostic evaluation, and for intraoperative monitoring. There is a considerable literature that describes the properties of SEPs in the infant and young child. Techniques for assessing the descending pathways have been developed in the last 10 years. These techniques hold great promise as both diagnostic and intraoperative monitoring tools. Many questions, however, still exist concerning their value and use. The rapidly increasing capability available in computer systems is also providing enhanced capability in the acquisition, display, and analysis of neurophysiologic data. It is now common to acquire multiple responses simultaneously, e.g. tibial SEPs, pudendal SEPs, and motor potentials. It is also possible to apply computationally intensive numerical algorithms in real time to enhance signal quality and reduce the time required to produce an interpretable display. Finally, it is possible to monitor multiple cases simultaneously from remote locations. These enhanced computational capabilities are helping to optimize the contribution of neurophysiologic monitoring to patient care.

Child↗
PubMed1994

Recovery from propofol anesthesia: a quantitative electroencephalographic analysis.

Four numerical descriptors (median frequency, spectral edge frequency-95%, total power, and delta-ratio) derived from the computer-processed electroencephalogram (Neurometrics Lifescan) were analyzed for their ability to predict imminent arousal from total intravenous anesthesia with propofol. Fifteen patients undergoing minor surgical procedures without intubation were enrolled in the study. Arousal was defined as eye opening in response to verbal stimuli. During emergence from propofol, there were no significant changes among the descriptors except the delta-ratio. Significant change of delta-ratio occurred 210 seconds before patients' arousal and thereafter. An increase of delta-ratio value indicates that patients shifted from anesthetic to arousal state. It is concluded that the degree of delta-ratio change may be used for predicting patients' arousal from propofol anesthesia.

Adult↗
PubMed1994

Waveform and latency estimation from neuroelectric signals using the bispectrum.

A technique based on bispectra and cross-bispectra is described for estimating waveform and latency from a set of noisy signals with variable latency. Waveform estimation is performed by averaging bispectra of observed noisy signals. Latency estimation is performed by using the product function of a function derived from the cross-bispectrum and the cross-correlation. The method is numerically assessed by simulations, using a signal with uniformly distributed latency and computer-generated noise sequences.

Electroencephalography↗
PubMed1977

Development of food tables and use with computers. Review of nutrient data bases.

Numerous tables of food composition have been compiled since the 1890s to meet the needs for nutrient data by nutritionists, researchers, and consumers. Early tables included values for protein, fat, carbohydrate, and calories. By 1945, values for several vitamins and minerals were listed in tables of food composition. The contents of food composition tables have been updated and expanded as laboratory procedures for analyzing nutrients have been improved. A trend toward increased specificity for most nutrient classifications has resulted in consideration of up to one hundred nutritional components in the development of nutrient data bases. Tables of food composition have varied in number of food items, number of nutrients, and classification schemes. Food-group designations have been used in some tables as a technique to categorize data for similar food items. Computer-stored nutrient data bases tend to vary in much the same manner as printed tables of food composition. Computer-assisted diagnostic procedures for editing input data for validity and verifying reasonable relationships among nutrient data have been developed to detect data inconsistencies. As data for new food products are included and the effects of food processing methods are determined, food composition tables and computer-stored nutrient data bases are expected to become more comprehensive, reliable, and suitable for various uses.

Calorimetry↗
PubMed1993

Real-time identification of parameters of the ARMA model of the human EEG waveforms.

Electroencephalogram (EEG) can provide important information about the functioning of the human brain. In particular, the EEG waveforms manifest certain changes due to application of drugs, such as general anesthetics. Measurement of the changes in the EEG waveforms in real time, may therefore be used to determine the global effects of the administered drug. Among numerous mathematical techniques used in the analysis of the EEG waveforms, perhaps, the fast Fourier transform (FFT) is the most widely used. Recently some researchers have suggested the use of the autoregressive moving average (ARMA) model for the EEG analysis. In this method the coefficients of the ARMA model are identified and used to describe the waveform. We consider a first order ARMA model, and use the Extended Least Squares (ELS) and its recursive version (RELS) for parameter estimation. The identified parameters are then used to describe the time-domain or the frequency-domain properties of the EEG waveforms. Since the parameters of the model may change with time, a forgetting factor is incorporated in the RELS algorithm to allow for tracking of time varying parameters. The advantage of recursive estimation of the coefficients of the ARMA model over the non-recursive estimation and the FFT method, is substantial reduction in computation as well as its capability to track the time varying process.

Algorithms↗
PubMed1993

Image analysis in cytology: DNA-histogramming versus cervical smear prescreening.

The visual inspection of cellular specimens and histological sections through a light microscope plays an important role in clinical medicine and biomedical research. The human visual system is very good at the recognition of various patterns but less efficient at quantitative assessment of these patterns. Some samples are prepared in great numbers, most notably the screening for cervical cancer, the so-called PAP-smears, which results in hundreds of millions of samples each year, creating a tedious mass inspection task. Numerous attempts have been made over the last 40 years to create systems that solve these two tasks, the quantitative supplement to the human visual system and the automation of mass screening. The most difficult task, the total automation, has received the greatest attention with many large scale projects over the decades. In spite of all these efforts, still no generally accepted automated prescreening device exists on the market. The main reason for this failure is the great pattern recognition capabilities needed to distinguish between cancer cells and all other kinds of objects found in the specimens: cellular clusters, debris, degenerate cells, etc. Improved algorithms, the ever-increasing processing power of computers and progress in biochemical specimen preparation techniques make it likely that eventually useful automated prescreening systems will become available. Meanwhile, much less effort has been put into the development of interactive cell image analysis systems. Still, some such systems have been developed and put into use at thousands of laboratories worldwide. In these the human pattern recognition capability is used to select the fields and objects that are to be analysed while the computational power of the computer is used for the quantitative analysis of cellular DNA content or other relevant markers. Numerous studies have shown that the quantitative information about the distribution of cellular DNA content is of prognostic significance in many types of cancer. Several laboratories are therefore putting these techniques into routine clinical use. The more advanced systems can also study many other markers and cellular features, some known to be of clinical interest, others useful in research. The advances in computer technology are making these systems more generally available through decreasing cost, increasing computational power and improved user interfaces. We have been involved in research and development of both automated and interactive cell analysis systems during the last 20 years. Here some experiences and conclusions from this work will be presented as well as some predictions about what can be expected in the near future.

Cervix Uteri↗
PubMed1993

[The development of a computer model in the quantitative assessment of thallium-201 myocardial scintigraphy].

Thallium-201 scintigraphy is a widely used noninvasive procedure for the detection and prognostic assessment of patients with suspected or proven coronary artery disease. Thallium uptake can be evaluated by a visual analysis or by a quantitative interpretation. Quantitative scintigraphy enhances disease detection in individual coronary arteries, provides a more precise estimate of the amount of ischemic myocardium, distinguishing scar from hypoperfused tissue. Due to the great deal of data, analysis, interpretation and comparison of thallium uptake can be very complex. We designed a computer-based system for the interpretation of quantitative thallium-201 scintigraphy data uptake. We used a database (DataEase 4.2-DataEase Italia). Our software has the following functions: data storage; calculation; conversion of numerical data into different definitions classifying myocardial perfusion; uptake data comparison; automatic conclusion; comparison of different scintigrams for the same patient. Our software is made up by 4 sections: numeric analysis, descriptive analysis, automatic conclusion, clinical remarks. We introduced in the computer system appropriate information, "logical paths", that use the "IF ... THEN" rules. The software executes these rules in order to analyze the myocardial regions in the 3 phases of scintigraphic analysis (stress, redistribution, re-injection), in the 3 projections (LAO 45 degrees, LAT,ANT), considering our uptake cutoff, obtaining, finally, the automatic conclusions. For these reasons, our computer-based system could be considered a real "expert system".

Computer Simulation↗
PubMed1995

ComputerLink: the impact of a computer network on Alzheimer's caregivers' decision-making confidence and skill.

1. INTRODUCTION. Decision-making demands faced by homebound caregivers of persons with Alzheimer's Disease (AD) are numerous and complex. Although caregivers frequently know what to do in caring for the person with AD, they lack confidence in their decisions [1]. The challenge of caregiving decisions may be compounded by the lack of resources to aid in decision-making or affirm decisions made. Because many caregivers are homebound, they are unable to avail themselves of traditional health and social services. ComputerLink, computer network, was designed to address the needs of these homebound caregivers. 2. DESCRIPTION. The ComputerLink consisted of a set of specialized programs and utilities residing within a public computer network. The three main features of the ComputerLink, which may provide aid to caregivers in decision making, include: the electronic encyclopedia (EE); a communications utility composed of a question and answer bulletin board (Q&A) and public (Forum) and private mail services; and a decision support module (DSM). The EE contained illness-specific information to support decision-making. The Forum and private mail provided caregivers with a means to interact with peers and professionals about their caregiving decisions. Q&A provided the opportunity to ask questions about caregiving and receive feedback from professionals and peers. The DSM could be accessed to gain information about decision-making or to actually work through a decision problem. The DSM was built on a multi-attribute utility model which employed English-language questions to guide users through a decision analysis. The analysis strategy was designed to help the user focus on the values and trade-offs that occur during difficult choices. The impact of ComputerLink on decision confidence and skill was evaluated as part of a larger randomized experiment. 102 AD caregivers were recruited: 51 caregivers in the control group and 47 in the experimental group completed the 12-month study. The mean age of the caregivers was 60 years. Thirty-three percent were male and 28 percent were Black. The groups did not differ in demographic characteristics. The ComputerLink interface was menu-driven and the system was available 24 hours. ComputerLink use was captured through a passive monitoring system. AD caregivers accessed ComputerLink a total of 3,875 times, with a mean access per individual of 83 (range: 3 - 590). The mean length of an encounter was 13 minutes; subjects typically accessed two or more functions during this time. The decision support model was accessed 91 times. The communication functions were most frequently used (3,724 Forum accesses and 1,888 private mail); the information utility was accessed 518 times. 3. RESULTS. Decision confidence was objectively measured using a modification of the Saunders and Courtney confidence-in-decision making instrument. Caregivers who had access to ComputerLink experienced greater confidence in decision-making than caregivers in the control group (t = 2.73, p < .01). Access to ComputerLink did not alter decision skill as measured by the number of alternative solutions generated for two self-identified decisions problems (t = .18, p < .05). Decision-making confidence correlated positively with ComputerLink accesses (r = .32, p = < .02) and with length of time spent on ComputerLink (r = .30, p = < .02). 56% of the AD caregivers reported that use of ComputerLink increased both their confidence and skill in decision making, though only 38 percent reported using the DSM to make a decision. 4. DISCUSSION. Access to ComputerLink increased decision-making confidence, but not decision-making skill in AD caregivers. The impact of ComputerLink on decision confidence, and not skill, may be related to the differential use of the utilities. (abstract truncated)

Alzheimer Disease↗
PubMed1996

An expert diagnostic system based on neural networks and image analysis techniques in the field of automated cytogenetics.

In this study, we introduce an expert system for intelligent chromosome recognition and classification based on artificial neural networks (ANN) and features obtained by automated image analysis techniques. A microscope equipped with a CCTV camera, integrated with an IBM-PC compatible computer environment including a frame grabber, is used for image data acquisition. Features of the chromosomes are obtained directly from the digital chromosome images. Two new algorithms for automated object detection and object skeletonizing constitute the basis of the feature extraction phase which constructs the components of the input vector to the ANN part of the system. This first version of our intelligent diagnostic system uses a trained unsupervised neural network structure and an original rule-based classification algorithm to find a karyotyped form of randomly distributed chromosomes over a complete metaphase. We investigate the effects of network parameters on the classification performance and discuss the adaptability and flexibility of the neural system in order to reach a structure giving an output including information about both structural and numerical abnormalities. Moreover, the classification performances of neural and rule-based system are compared for each class of chromosome.

Algorithms↗
PubMed1996

Data-driven approaches to decision making in automated tumor grading. An example of astrocytoma grading.

OBJECTIVE: To compare four data-driven approaches to automated tumor grading based on morphometric data. Apart from the statistical procedure of linear discriminant analysis, three other approaches from the field of neural computing were evaluated. STUDY DESIGN: The numerical basis of this study was computed tomography-guided, stereotactically obtained astrocytoma biopsies from 86 patients colored with a combination of Feulgen and immunhistochemical Ki-67 (MIB1) staining. In these biopsies the cell nuclei in four consecutive fields of vision were evaluated morphometrically and the following parameters determined: relative nuclei area, secant lengths of the minimal spanning trees and relative volume-weighted mean nuclear volumes of the proliferating nuclei. RESULTS: Based on the analysis of these morphometric features, the multivariate-generated HOM grading system provides the highest correct grading rates (> 90%), whereas the two widely employed qualitative histologic grading systems for astrocytomas yield correct grading rates of about 60%. For automated tumor grading all approaches yield similar grading results; however, back-propagation networks provide reliable results only following an extensive training phase, which requires the use of a supercomputer. All other neurocomputing models can be run on simple UNIX workstations (AT&T, U.S.A). CONCLUSION: In contrast to discriminant analysis, backpropagation and Kohonen networks, the newly developed neural network architecture model of self-editing nearest neighbor nets (SEN3) provides incremental learning; i.e., the training phase does not need to be restarted each time when there is further information to learn. Trained SEN3 networks can be considered ready-to-use knowledge bases and are appropriate to integrating further morphometric data in a dynamic process that enhances the diagnostic power of such a network.

Algorithms↗
PubMed1996

Waveform estimation techniques for event-related bioelectric signals: a study of performance.

Many bioelectric signals result from the electrical response of a physiological system to an impulse that can be internal (ECG signals) or external (evoked potentials). A comparative study of performance of seven waveform estimation techniques used for event-related signals that are time-locked to a stimulus is presented in this paper. Computer generate 1 signals and noise for several signal-to-noise ratios (SNRs) are used to make ensembles of simulated noisy waveforms. The performance of each technique is numerically investigated using the root-mean-squared error and two well known SNR estimators. The results show that an adaptive impulse correlated filter performs the best. It is capable of estimating the deterministic component of the signal and removes the noise uncorrelated with stimulus even if this noise is colored and without the need for prealignment.

Computer Simulation↗
PubMed1996

Wavelets, adapted waveforms and de-noising.

This is a short summary of a talk given at the Frontier Science in EEG Symposium, Continuous Waveform Analysis, held on 9 October 1993 in New Orleans. We describe some new libraries of waveforms well-adapted to various numerical analysis and signal processing tasks. The main point is that by expanding a signal in a library of waveforms which are well-localized in both time and frequency, one can achieve both understanding of structure and efficiency in computation. We briefly cover the properties of the new "wavelet packet" and "localized trigonometric" libraries. The main focus will be applications of such libraries to the analysis of complicated transient signals: a feature extraction and data compression algorithm for speech signals which uses best-adapted time and frequency decompositions, and an adapted waveform analysis algorithm for removing fish noises from hydrophone recordings. These signals share many of the same properties as EEG traces, but with distinct features that are easier to characterize and detect.

Electricity↗