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Biomedical subjects

P Degoulet

Publications and source records attributed to P Degoulet.

At least 55 records · Page 3Linked to original sources

Critical dimensions in medical informatics.

A typology of medical informatics applications is proposed around three dimensions: the dimension of care, the dimension of information and knowledge, and the aspects of the computerized society. These dimension can help both to evaluate application or research papers in the field or to derive long term goals for the discipline. In the first dimension medical informatics appears more as a technology driven by external forces such as the general progress of medicine or the integration of economical constraints in the choice of optimal procedures. It is argued that barriers to overcome as well as challenges for future research mainly remain in the two last dimensions.

Artificial Intelligence↗

Fuzzy classification of renal artery lesions from angiograms in the context of angioplasty.

This paper describes a system that automatically classifies renal artery lesions from arteriograms in the context of Percutaneous Transluminal Renal Angioplasty (PTRA). PTRA outcomes have been categorized into type A (success) or type B (failure) according to morphological features. The morphological features are naturally represented by fuzzy sets. The classification process is based on a fuzzy pattern matching procedure between fuzzy prototypes of lesions in the classes A and B and fuzzy quantified assessments of lesions in angiograms. The system provides a meaningful membership degree to the class rather than an abrupt yes or no answer. The system is expected to be a good framework to study the technical results of PTRA according to the anatomy of the lesion.

Angioplasty, Balloon↗

Automatic stenosis detection and quantification in renal arteriography.

Visual assessment of the degree of renal artery stenosis on renal arteriography has a large inter- and intraobserver variability. This degree is usually estimated by the ratio between the most narrowed portion of the artery and the reference diameter. The latter is a priori unknown information and thus operator dependent. The objective of the present work was to test the performances of a computer system that was designed to analyze and quantify lesions on 2D renal arteriograms. The main hypothesis was to consider that the most frequent diameter computed along the artery was a good candidate to approximate the reference diameter. Forty nine patient images were collected from the EMMA randomized trial, a multicenter study comparing two treatment strategies in unilateral atheromatous renal artery stenosis of at least 60%. For each image, the degree of stenosis was evaluated by five independent experts and the mean value was used to represent the gold standard for the computer system. The system is based on a fuzzy automaton and performs a syntactic analysis of the arterial segment providing automatic and reproducible quantification of lesions. Both the radiologist caring for the patient and the system were compared to the gold standard. Compared to individual radiologists, the computer system gave a more precise estimation of percent stenosis and did not over or under estimate the severity of the lesion.

Fuzzy Logic↗

The number needed to treat: a clinically useful nomogram in its proper context.

The number needed to treat is a meaningful way of expressing the benefit of an active treatment over a control. It can be used either for summarising the results of a therapeutic trial or for medical decision making about an individual patient, but its use at the bedside has been impeded by the need for time consuming calculations. A nomogram has therefore been devised that will greatly simplify the calculations. Since calculations are now easy, the number needed to treat can be used to access the value of several interventions, although it does have its limitations. In particular it should not be used when it is not known whether the relative risk reduction associated with an intervention is constant for all levels of risk, or for periods of time longer than that studied in the original trials.

Clinical Trials as Topic↗

[Introduction to quantitative semiology].

Clinicians regularly confront dilemmas when ordering and interpreting diagnostic tests. This paper presents the basic principles necessary for the critical appraisal of articles about diagnostic tests. Basic notions such as sensitivity and specificity are defined. The advantages of using the newer notion of likelihood ratios are underlined. Since all these quantities are estimates of unknown true values, the method for calculating confidence intervals are reported. Finally, the simplified expression of Bayes' theorem based on the use of likelihood ratios is described alongside with a simple nomogram making it possible to calculate posttest probabilities at the bedside.

Bayes Theorem↗

[Computer-assisted medical decision].

A physician deals everyday with uncertainty to take decisions and treat patients. The goal of decision making systems is to facilitate and improve the decision. Classical approaches, such as decision trees or statistical tools, provide rates about possible actions and outcomes of physicians' decisions. Such information is essentially numerical. Other computer approaches, like expert systems, provide both numeric and symbolic information. The expert knowledge is embedded in the system and used to elaborate new decisions and to provide reasoning explanations. The use of computer making decision systems will certainly increase the performances in future medical activity as it will provide a reliable additional expert information to take decisions.

Algorithms↗

[The multimedia workstation, electronic assistant to the health care professional].

The health professional multimedia workstation is the natural entry point to health and knowledge networks. It should allow an easy and transparent management of all the data necessary for patient management. Multimedia nature of processed information reflects evolution of medical techniques that involve more and more complex objects such as video sequences or digitized signals. Workstations can be considered from 3 points of view: the professional end-users, the developers and the decision makers. The long term goal for the end-user is to establish an easy access in a working environment, that gives him/her the feeling of a single comprehensive application running on a single computer when the information system relies on a set of heterogeneous and geographically distributed components. Development of a workstation requires the integration into the same environment of tools to localize, access, manipulate and communicate the required information within a health information network. Analysis of the 445 Medline-indexed publications for the January 1991 to December 1994 period, that included the word workstation either in their title or in their abstract, helps in refining objectives and challenges both for the health professionals and the decision makers.

Computer Terminals↗

The health care professional multimedia workstation: development and integration issues.

Workstations for health care professionals provide access to distributed healthcare information systems. They are complex systems that have to manage, in a unified framework, the distributed and multimedia information needed for optimal patient care. The objective is to provide the end-user with a virtual and unified device that conceals the complexity of the underlying information system. Integration and reuse of modular software components are important in the development of such a workstation. A reference set of evaluation criteria is proposed that includes functional, technical, organizational, medical, cultural and ethical, economic and industrial components.

Computer Communication Networks↗

The image related services of the HELIOS software engineering environment.

This paper describes the approach of the European HELIOS project to integrate image processing tools into ward information systems. The image processing tools are the result of the basic research in image analysis in the Department Medical and Biological Informatics at the German Cancer Research Center. These tools for the analysis of two-dimensional images and three-dimensional data volumes with 3D reconstruction and visualization ae part of the Image Related Services of HELIOS. The HELIOS software engineering environment allows to use the image processing functionality in integrated applications.

Computer Communication Networks↗

Legacy systems: managing evolution through integration in a distributed and object-oriented computing environment.

Legacy systems are crucial for organizations since they support key functionalities. But they become obsolete with aging and the apparition of new techniques. Managing their evolution is a key issue in software engineering. This paper presents a strategy that has been developed at Broussais University Hospital in Paris to make a legacy system devoted to the management of health care units evolve towards a new up-to-date software. A two-phase evolution pathway is described. The first phase consists in separating the interface from the data storage and application control and in using a communication channel between the individualized components. The second phase proposes to use an object-oriented DBMS in place of the homegrown system. An application example for the management of hypertensive patients is described.

Computer Communication Networks↗

An object oriented computer-based patient record reference model.

In the context of health care information systems based on client/server architecture, we address the problem of a common Computer-based Patient Record (CPR). We define it as a collection of faithful observations about patients care, with respect to the free expression of physicians. This CPR model supports several views of the medical data, in order to provide applications with a comprehensive and standardized access to distributed patient data. Finally, we validated our CPR approach as a primary data model server for an application for hypertensive patient management.

Artificial Intelligence↗

A development environment to create medical applications.

This paper describes a Development Environment for medical applications developers coupling Reuse and Object-Oriented technologies. It presents the two main phases of the reuse process, the reusable component creation and the reusable component use, and stresses on the very nature of reusable development components. We provide both a classification model for those reusable components that is a support for an efficient and simple retrieval mechanism, and a reusable component model that considers the same way components of large and low-granularity levels (e.g., application frameworks and methods of a given class). The reusable component model is based on the underlying idea that development components are not operational components since they do not have the same purpose. This model first represents each component as an aggregation of other sub-components, together with all information needed for its retrieval (e.g., classification and facets), its understanding (e.g., informal functional description), and its dependencies with other development components, in particular the applications in which it occurs, since applications are considered here as abstract development components.

Databases, Factual↗

Integrated image processing in clinical applications: the HELIOS approach.

This paper describes the approach of the European HELIOS project to integrate image processing tools into ward information systems. The image processing tools are the result of the basic research in image analysis in the Department Medical and Biological Informatics at the German Cancer Research Center. Tools for the analysis of 2-dimensional images and 3-dimensional data volumes with 3-dimensional reconstruction and visualization are part of the Image Related Services of HELIOS.

Europe↗

Do physicians estimate reliably the cardiovascular risk of hypertensive patients?.

For hypertension management, it is increasingly recommended to individualize treatment according to the individual patient's characteristics. However, the ability of physicians to predict the patient's risk in the absence of a computer aid is unknown. Our aim was to determine if senior hypertension specialists were able to assess reproducibly cardiovascular disease (cvd) risk in hypertensive patients. The records of 100 patients were selected at random from the ARTEMIS database. The group comprised 53% of males, mean age was 43.7 (15), blood pressure 160 (25) / 99 (12) mmhg and serum cholesterol 5.6 (1.1) mmol/l. The records were summarized on a standardized form. Nineteen items were devoted to general characteristics and medical history of patients, 15 to clinical examination and 7 to biological tests. These items have been chosen because they were used in the framingham cvd risk prediction equation and/or had decisional value in a bayesian program designed for secondary hypertension diagnosis. Six physicians, twice at one month intervals, assigned each patient to one of the three categories of risk (low, moderate, high). The order of cases was randomized. Chance corrected agreement (intra-physician agreement) between the two estimations was only moderate except for one expert (kappa values: 0.658, 0,543, 0.439, 0.363, 0.328 and 0.207 for each expert, respectively). The proportion of patients assigned by each physician to each category ranged from 22.7% to 77.3% for the low risk, and from 4.5% to 43.9% for the high risk category. One physician overestimated risk, one underestimated it and the three others were in keeping with framingham predictions. Bias and lack of reproducibility influence physician judgment in assessing cvd risk of hypertensive patients. Application of computer aids could result in more rational assessments and better decision making.

Adolescent↗

Representing clinical narratives using conceptual graphs.

The analysis of medical narratives and the generation of natural language expressions are strongly dependent on the existence of an adequate representation language. Such a language has to be expressive enough in order to handle the complexity of human reasoning in the domain. Sowa's Conceptual Graphs (CG) are an answer, and this paper presents a multilingual implementation, using French, English and German. Current developments demonstrate the feasibility of an approach to natural Language Understanding where semantic aspects are dominant, in contrast to syntax driven methods. The basic idea is to aggregate blocks of words according to semantic compatibility rules, following a method called Proximity Processing. The CG representation is gradually built, starting from single words in a semantic lexicon, to finally give a complete representation of the sentence under the form of a single CG. The process is dependent on specific rules of the medical domain, and for this reason is largely controlled by the declarative knowledge of the medical Linguistic Knowledge Base.

Artificial Intelligence↗

Decision support systems from the standpoint of knowledge representation.

Relationships between decision-support systems and knowledge representation are examined from three different points of view: the characteristics of medical decisions that might influence the selection of appropriate knowledge representations,--the extent to which different knowledge representations can support efficient medical decisions and,--the validation of knowledge hypotheses through the practice of decision support systems. A three-level model of knowledge representation is proposed that includes a contextual, a conceptual and a computational level. Taking into consideration the context that leads to the selection of a given representation raises the issue of multiexpertise and multirepresentation modeling. Implementation of decision support systems as sets of cooperative agents and integration in the health information systems are considered.

Artificial Intelligence↗

Integration of data driven decision support into the HELIOS environment.

The development of large-scale, clinically accepted decision support systems (DSS) calls for powerful and commonly available methods and tools for knowledge acquisition, system realisation, and knowledge base maintenance. The paper addresses problems associated with the integration of knowledge-based systems within the clinical setting with special reference to (i) data driven decision support, (ii) the Arden Syntax as a knowledge representation format and, (iii) the HELIOS software engineering environment. Architecture of a DSS based on Arden Syntax and its integration in the HELIOS environment are presented. Realisation of the DSS is discussed in relation to client-server architecture and object-oriented databases, which are essential concepts of the HELIOS environment. Sharability and reusability of the knowledge, together with commonality of used software tools are also discussed.

Database Management Systems↗

Design and processing issues for the health care professional workstation: summary and recommendations.

The health care professional workstation is a window to a heterogeneous set of functions that need to be ported to various types of hardware for different types of users. Processing aspects, which belong with the interface, storage and communication, to the architectural dimension of the workstation should not be considered outside of a more comprehensive model including the user, function and time dimensions. Several recommendations, which could provide the appropriate environment for development and help maintain a viable approach as the variables change along the four dimensions of the workstation model, are proposed. They concern the adaptation of the enterprise infrastructure to integrate workstations, the need for a reference architecture for health care workstation development and recommendations for the evaluation and dissemination of results.

Computer Communication Networks↗