Computers and biomedical research, an international journal最新文献

{"title":"Enhancing the Precision of ECG Baseline Correction: Selective Filtering and Removal of Residual Error","authors":"Vladimir Shusterman,&nbsp;Syed Ismail Shah,&nbsp;Anna Beigel,&nbsp;Kelley P. Anderson","doi":"10.1006/cbmr.2000.1539","DOIUrl":"10.1006/cbmr.2000.1539","url":null,"abstract":"<div><p>Reemergence of the problem of baseline correction is related to recent advancements in the electrocardiographic (ECG) analysis of beat-to-beat repolarization changes which play an important role in risk assessment and the prediction of sudden cardiac death. These alterations often have an amplitude of a few microvolts and duration of several milliseconds and their detection requires special accuracy of baseline estimation. Using detailed analysis of various types of residual errors we designed a two-step procedure for selective filtering of ECG and removal of residual error with minimal distortion of cardiac complexes and tested this approach on 100 simulated and 210 real ECG signals. Application of this procedure provided a twofold reduction in the error of baseline estimation and T-wave amplitude measurements compared to high-pass filtering. Selective application of this approach to the segments with low baseline drift allowed analysis of low-amplitude, beat-to-beat changes in repolarization during more than 70% of the recording time.</p></div>","PeriodicalId":75733,"journal":{"name":"Computers and biomedical research, an international journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/cbmr.2000.1539","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21697961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computer Modeling of Population Exposure to a Carcinogen: The Example of Asbestos and Mesothelioma Mortality in France","authors":"Alireza Banaei ,&nbsp;Bertran Auvert ,&nbsp;Marcel Goldberg","doi":"10.1006/cbmr.1999.1536","DOIUrl":"10.1006/cbmr.1999.1536","url":null,"abstract":"<div><p>The multistage theory of carcinogenesis allows models to be constructed that provide the individual probability of a diagnosed tumor at a given age as a function of the person's past exposure to carcinogenic agents (exposure level versus age), the time since exposure, and age. When exposure to a carcinogenic agent and its impact in terms of morbidity and mortality are modeled on the scale of the general population, individual exposures must often be estimated. If appropriate data do not already exist, this difficult task necessitates expensive and difficult investigations. We propose here a method that allows this global exposure to be modeled without needing to know the individual exposures. The method is used and illustrated in the context of modeling the asbestos exposure of the French male population and calculating its mortality rate from mesothelioma (a type of cancer for which asbestos is the only carcinogen and for which a risk function based on the multistage theory of carcinogenesis exists). This method assumes that the exposure functions (how exposure levels vary with age) for all individuals are the same, with the exception of one parameter. That is, it utilizes a hypothesis that we called the hypothesis of the Standard Exposure Window (SEW). We used two methods to calculate the probability of death from mesothelioma in a representative sample of the French male population for whom individual histories of asbestos exposure are known: we applied the risk function to all the individuals, and we applied the SEW hypothesis. The number of deaths obtained by the two methods are very close and fit the observed mortality data satisfactorily.</p></div>","PeriodicalId":75733,"journal":{"name":"Computers and biomedical research, an international journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/cbmr.1999.1536","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21697958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Use of the Personalized Estimate of Death Probabilities for Medical Decision Making","authors":"R. Giorgi ,&nbsp;J. Gouvernet ,&nbsp;E. Jougla ,&nbsp;G. Chatellier ,&nbsp;P. Degoulet ,&nbsp;M. Fieschi","doi":"10.1006/cbmr.1999.1531","DOIUrl":"10.1006/cbmr.1999.1531","url":null,"abstract":"<div><p>Data coming from the French national statistics on the cause of deaths are used to calculate the probabilities of death from pathologies. These probabilities are calculated according to age, sex, and place of residence of the patient to “personalize” the estimate. This individual prediction of the risk of death is proposed for pathologies for which the feasibility and the utility of prevention measures had been demonstrated. Relative risks of death according to the socioprofessional category, which are coming from the scientific literature, are used to adjust the probabilities of death as a function of the patient socioprofessional category. The aim of this work is to guide a scientist toward a prevention strategy according to the age and characteristics of patient. The use of computers by the scientists will make possible the diffusion of such tool of prediction to improve a personalized prevention.</p></div>","PeriodicalId":75733,"journal":{"name":"Computers and biomedical research, an international journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/cbmr.1999.1531","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21622802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constructing a 3-D Mesh Model for Electrical Cardiac Activity Simulation","authors":"Chia-Hung Hsiao,&nbsp;Tsair Kao","doi":"10.1006/cbmr.1999.1528","DOIUrl":"10.1006/cbmr.1999.1528","url":null,"abstract":"<div><p>The 3-D ventricle model in this study was reconstructed from a series of MRI torso cross-section data. We used a 3-D voxel array to represent the ventricle. As in cardiac simulations proposed by previous studies, the activation sequence and body surface ECG were simulated in this model. But to reduce the amount of elements in the model, so that the amount of parameters in the model can be handled numerically, we propose another approach to simulate cardiac activity. A mesh model was constructed on the closed surface formed by epicardiac and endocardiac surfaces of the ventricle. We propose a method to simulate the activation sequence on the epicardiac and endocardiac surfaces of the mesh model. As with the uniform double layer theorem, body surface ECG can be estimated in terms of epicardiac and endocardiac surface current source. Consequently, we can also generate ECG waveforms corresponding to this mesh simulation. Both the depolarization sequence and ECG simulated by the mesh model resemble those generated by the 3-D voxel model. However, the mesh model greatly simplified the process of ECG simulation. Both the simulation of depolarization and ECG estimation were expressed in terms of clear and simple mathematical representations. Consequently, we can analytically investigate the effects of the mesh model's parameters on the cardiac activation sequence and ECG. It could be a useful tool to numerically study the relation of ECG waveforms and electrical activity of the heart.</p></div>","PeriodicalId":75733,"journal":{"name":"Computers and biomedical research, an international journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/cbmr.1999.1528","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21622799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison between Human and Artificial Neural Network Detection of Laplacian-Derived Electroencephalographic Activity Related to Unilateral Voluntary Movements","authors":"Fabio Babiloni ,&nbsp;Filippo Carducci ,&nbsp;Sergio Cerutti ,&nbsp;Diego Liberati ,&nbsp;Paolo M. Rossini ,&nbsp;Antonio Urbano ,&nbsp;Claudio Babiloni","doi":"10.1006/cbmr.1999.1529","DOIUrl":"10.1006/cbmr.1999.1529","url":null,"abstract":"<div><p>A back-propagation artificial neural network (ANN) was tested to verify its capacity to select different classes of single trials (STs) based on the spatial information content of electroencephalographic activity related to voluntary unilateral finger movements. The rationale was that ipsilateral and contralateral primary sensorimotor cortex can be involved in a nonstationary way in the control of unilateral voluntary movements. The movement-related potentials were surface Laplacian-transformed (SL) to reduce head volume conductor effects and to model the response of the primary sensorimotor cortex. The ANN sampled the SL from four or two central channels overlying the primary motor area of both sides in the period of 80 ms preceding the electromyographic response onset in the active muscle. The performance of the ANN was evaluated statistically by calculating the percentage value of agreement between the STs classified by the ANN and those of two investigators (used as a reference). The results showed that both investigator and ANN were capable of selecting STs with the SL maximum in the central area contralateral to the movement (contralateral STs, about 25%), STs with considerable SL values also in the ipsilateral central area (bilateral STs, about 50%), and STs with neither the contralateral nor bilateral pattern (“spatially incoherent” single trials; about 25%). The maximum agreement (64–84%) between the ANN and the investigator was obtained when the ANN used four spatial inputs (<em>P</em> &lt; 0.0000001). Importantly, the common means of all single trials showed a weak or absent ipsilateral response. These results may suggest that a back-propagation ANN could select EEG single trials showing stationary and nonstationary responses of the primary sensorimotor cortex, based on the same spatial criteria as the experimenter.</p></div>","PeriodicalId":75733,"journal":{"name":"Computers and biomedical research, an international journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/cbmr.1999.1529","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21622801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coding Neuroradiology Reports for the Northern Manhattan Stroke Study: A Comparison of Natural Language Processing and Manual Review","authors":"Jacob S. Elkins ,&nbsp;Carol Friedman ,&nbsp;Bernadette Boden-Albala ,&nbsp;Ralph L. Sacco ,&nbsp;George Hripcsak","doi":"10.1006/cbmr.1999.1535","DOIUrl":"10.1006/cbmr.1999.1535","url":null,"abstract":"<div><p>Automated systems using natural language processing may greatly speed chart review tasks for clinical research, but their accuracy in this setting is unknown. The objective of this study was to compare the accuracy of automated and manual coding in the data acquisition tasks of an ongoing clinical research study, the Northern Manhattan Stroke Study(NOMASS). We identified 471 neuroradiology reports of brain images used in the NOMASS study. Using both automated and manual coding, we completed a standardized NOMASS imaging form with the information contained in these reports. We then generated ROC curves for both manual and automated coding by comparing our results to the original NOMASS data, where study in investigators directly coded their interpretations of brain images. The areas under the ROC curves for both manual and automated coding were the main outcome measure. The overall predictive value of the automated system (ROC area 0.85, 95% CI 0.84–0.87) was not statistically different from the predictive value of the manual coding (ROC area 0.87, 95% CI 0.83–0.91). Measured in terms of accuracy, the automated system performed slightly worse than manual coding. The overall accuracy of the automated system was 84% (CI 83–85%). The overall accuracy of manual coding was 86% (CI 84–88%). The difference in accuracy between the two methods was small but statistically significant (<em>P</em> = 0.026). Errors in manual coding appeared to be due to differences between neurologists' and nueroradiologists' interpretation, different use of detailed anatomic terms, and lack of clinical information. Automated systems can use natural language processing to rapidly perform complex data acquisition tasks. Although there is a small decrease in the accuracy of the data as compared to traditional methods, automated systems may greatly expand the power of chart review in clinical research design and implementation.</p></div>","PeriodicalId":75733,"journal":{"name":"Computers and biomedical research, an international journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/cbmr.1999.1535","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21622879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Augmented Reality Simulator for Training in Two-Dimensional Echocardiography","authors":"M. Weidenbach ,&nbsp;C. Wick ,&nbsp;S. Pieper ,&nbsp;K.J. Quast ,&nbsp;T. Fox ,&nbsp;G. Grunst ,&nbsp;D.A. Redel","doi":"10.1006/cbmr.1999.1527","DOIUrl":"10.1006/cbmr.1999.1527","url":null,"abstract":"<div><p>In two-dimensional echocardiography the sonographer must synthesize multiple tomographic slices into a mental three-dimensional (3D) model of the heart. Computer graphics and virtual reality environments are ideal to visualize complex 3D spatial relationships. In augmented reality (AR) applications, real and virtual image data are linked, to increase the information content. In the presented AR simulator a 3D surface model of the human heart is linked with echocardiographic volume data sets. The 3D echocardiographic data sets are registered with the heart model to establish spatial and temporal congruence. The heart model, together with an animated ultrasound sector represents a reference scenario, which displays the currently selected two-dimensional echocardiographic cutting plane calculated from the volume data set. Modifications of the cutting plane within the echocardiographic data are transferred and visualized simultaneously and in real time within the reference scenario. The trainee can interactively explore the 3D heart model and the registered 3D echocardiographic data sets by an animated ultrasound probe, whose position is controlled by an electromagnetic tracking system. The tracking system is attached to a dummy transducer and placed on a plastic puppet to give a realistic impression of a two-dimensional echocardiographic examination.</p></div>","PeriodicalId":75733,"journal":{"name":"Computers and biomedical research, an international journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/cbmr.1999.1527","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21622798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using an Artificial Neural Network to Detect Activations during Ventricular Fibrillation","authors":"Melanie T. Young ,&nbsp;Susan M. Blanchard ,&nbsp;Mark W. White ,&nbsp;Eric E. Johnson ,&nbsp;William M. Smith ,&nbsp;Raymond E. Ideker","doi":"10.1006/cbmr.1999.1530","DOIUrl":"10.1006/cbmr.1999.1530","url":null,"abstract":"<div><p>Ventricular fibrillation is a cardiac arrhythmia that can result in sudden death. Understanding and treatment of this disorder would be improved if patterns of electrical activation could be accurately identified and studied during fibrillation. A feedforward artificial neural network using backpropagation was trained with the Rule-Based Method and the Current Source Density Method to identify cardiac tissue activation during fibrillation. Another feedforward artificial neural network that used backpropagation was trained with data preprocessed by those methods and the Transmembrane Current Method. Staged training, a new method that uses different sets of training examples in different stages, was used to improve the ability of the artificial neural networks to detect activation. Both artificial neural networks were able to correctly classify more than 92% of new test examples. The performance of both artificial neural networks improved when staged training was used. Thus, artificial neural networks may beuseful for identifying activation during ventricular fibrillation.</p></div>","PeriodicalId":75733,"journal":{"name":"Computers and biomedical research, an international journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/cbmr.1999.1530","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21622800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sexual Behavior, Heterosexual Transmission, and the Spread of HIV in Sub-Saharan Africa: A Simulation Study","authors":"Bertran Auvert ,&nbsp;Gianluca Buonamico ,&nbsp;Emmanuel Lagarde ,&nbsp;Brian Williams","doi":"10.1006/cbmr.1999.1533","DOIUrl":"10.1006/cbmr.1999.1533","url":null,"abstract":"<div><p>A stochastic simulation model has been used to assess the extent to which variation in sexual behavior and transmission characteristics can explain the striking spatial heterogeneity in the prevalence of HIV among different geographical locations in sub-Saharan Africa. Of the various parameters describing sexual behavior the most important determinant of the spread of HIV is the proportion of men engaging in sexual relationships with people other than spouses, including contacts with sex workers and short-term partners. Considering factors other than sexual behavior the model shows that this heterogeneity in HIV prevalence could be the result of differences in the transmission probability of HIV or in the prevalence of other sexuality transmitted diseases. These factors could play a key role in determining the patterns of spread of HIV in sub-Saharan Africa and should be considered in the design of intervention strategies.</p></div>","PeriodicalId":75733,"journal":{"name":"Computers and biomedical research, an international journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/cbmr.1999.1533","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21622803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Familial Associations between Cancer Sites","authors":"Alun Thomas ,&nbsp;Lisa Cannon-Albright ,&nbsp;Aruna Bansal ,&nbsp;Mark H Skolnick","doi":"10.1006/cbmr.1999.1525","DOIUrl":"10.1006/cbmr.1999.1525","url":null,"abstract":"<div><p>The Utah Population Database links together genealogical records, the Utah Cancer Registry, and Utah death certificates and allows identification of cancer clusters. Groups of individuals with cancers of some types tend to fall into related clusters within the genealogy. We examine the apparent tendency of cases of two types of cancer to cluster together and distinguish real clusters from chance occurrences. Some established associations are found, whereas some are surprisingly absent. Some new associations are also suggested.</p></div>","PeriodicalId":75733,"journal":{"name":"Computers and biomedical research, an international journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/cbmr.1999.1525","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21445200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}