Biomedical subjects

P Degoulet

Publications and source records attributed to P Degoulet.

At least 37 records · Page 2Linked to original sources

PubMed2000

A property concept frame representation for flexible image-content retrieval in histopathology databases.

In histopathology databases, images descriptions are collections of properties provided by experts. Image content retrieval implies comparison of such properties. The objective of this work is to enrich the traditional attribute-value representation of properties in order to take into account the polymorphism and subjectivity of properties and to manage the comparison process. In this paper we define a property concept frame (PCF) representation based on fuzzy logic to handle both representation and comparison. Seven quantifiable morphological characteristics were selected from histopathological reports to illustrate the variety of fuzzy predicates and linguistic terms in properties. The PCF representation has been tested in the context of breast pathology. It is concluded that the PCF representation provides a unification scheme to retrieve in images morphological characteristics that are described in different ways. It may enhance the relevancy of applications in various contexts such as image content-based retrieval or case-based reasoning from images.

Breast↗

PubMed2000

Towards content-based image retrieval in a HIS-integrated PACS.

Development of a Picture Archiving and Communications System (PACS) with a large and diverse set of medical images will lead to large digital libraries that can be accessed to provide improved support for patient care, research and education. New representational and retrieval models for clinical images are required to address these issues. The PACS at the Georges Pompidou Hospital (GPH) is integrated in the hospital information system (HIS), and several modalities from medical imaging departments have been attached to it. The two main axes of the GPH PACS project were 1) HIS-integration to allow hospital-wide access to the images based on demographic and procedure-type information and 2) the development of content-based image retrieval to enhance the medical impact of image retrieval in daily practice.

Breast↗

PubMed1999

Interobserver variability in the interpretation of renal digital subtraction angiography.

OBJECTIVE: Our purpose was to analyze interobserver variability in the interpretation of renal digital subtraction angiography and to describe the main factors associated with observer discrepancies. MATERIALS AND METHODS: Forty-nine cases of unilateral atheromatous renal artery stenosis of more than 60% were quantified first by local investigators in a multicenter study and then by five other radiologists. Differences between radiologists for the minimum diameter (Dmin), the reference diameter (Dref), and the percentage of stenosis of the renal arteries were analyzed. Interpretations by the local investigators were then compared with the gold standard, defined as the mean for the five radiologists. RESULTS: The average SD for estimation of all renal artery stenoses by all radiologists was 7% for stenosis percentage, 0.5 mm for Dmin, and 0.7 mm for Dref. Main discrepancies occurred more frequently in cases of weakly opacified renal artery stenosis and poststenotic dilatation. The observations of local investigators disagreed by more than two SDs (14%) with the gold standard for 11 of 49 cases (22%). CONCLUSION: The accuracy of digital subtraction angiography in renal artery interpretations is poor because of variations in evaluating both Dmin and Dref. Precise and reproducible methods for quantification of renal artery stenosis are required.

Adult↗

PubMed1999

Quantifying stenosis in renal arteriograms: a fuzzy syntactic analysis.

The introduction of fuzzy logic improves a system for the automatic quantification of renal artery lesions seen in digital subtraction angiograms. A two-step approach has been followed. An earlier system based on non-fuzzy syntactic analysis provided a clear symbolic description of the stenotic lesions. Although this system worked correctly, it did not take into account the variability and uncertainty inherent to image processing and to knowledge on the reference diameter. This system has been improved by the introduction of fuzzy logic in the representation of the reference diameter. It provides a description of the stenosis in terms of fuzzy quantities. To illustrate the benefits of the fuzzy approach, the results of the two systems have been compared by plotting the differences of an index of variability. It appears that the differences are statistically different when using a two-tailed paired t-test (t = 2.37; p = 0.025). The result shows that the fuzzy approach is better than a non-fuzzy approach in the sense that the index of variability is reduced significantly.

Angiography, Digital Subtraction↗

PubMed1999

Decision aids for triage of patients with chest pain: a systematic review of field evaluation studies.

We performed an overview of published controlled trials to assess the overall effectiveness of decision aids directed at improving triage of patients with acute chest pain. Searches of the Medline database identified 11 randomized or quasi-randomized controlled trials testing various decision aids: risk stratification system (n = 6), practice guidelines (n = 3), and formalized protocols of care (n = 2). Sensitivity, specificity of the decision aid and length of stay (LOS) in the intensive care unit (ICU) were the main outcomes. Decision aids slightly modified sensitivity and specificity (available in 5 studies), but sensitivity was already high in reference groups. Among the 9 studies providing information on LOS, 7 showed a statistically significant difference favoring the decision aid. The level of evidence concerning the efficacy of decision aids in this domain is relatively low. Larger and appropriately designed clinical trials are required to show an impact on acute cardiac ischaemia complications and mortality.

Humans↗

PubMed1999

A visual coding system in histopathology and its consensual acquisition.

Divergent descriptions of histopathologic images induce inter- and intra-observer variability in diagnosis. Even though a controlled terminology exists to describe medical imaging, pathologists do not always agree on the visual representation of the descriptive terms. The main purpose of our work is to define a methodology to build a standardized visual coding system unambiguously characterizing the terms of a microglossary. The methodology follows two steps: 1) the acquisition of experts' descriptions of images using the microglossary and 2) a consensus derivation. The procedure was applied on a set of 85 histopathological images of breast tumors described by two experts. Among the 339 objects selected in images, 176 were detected by both experts, 77% localized at the same place and 25% also identically labeled. The microglossary was enriched and illustrated via the resulting consensual descriptions. The contribution of this work supports relevant indexing of biomedical images and image-related information.

Breast Neoplasms↗

PubMed1999

Decision aids for triage of patients with chest pain: a systematic review of field evaluation studies.

Chest Pain↗

PubMed1999

A critical appraisal of the use of Internet for calculating cardiovascular risk.

This paper aims to retrieve and evaluate the quality of the Internet sites providing information on cardiovascular risk. We searched web pages related to risk prediction using six search engines. Sites proposing a cardiovascular risk prediction were selected for evaluation. The quality of each site was checked against criteria testing the validity, type and potential usefulness of information for physicians or patients. Search engines retrieved about 50 10(6) web pages. Eight sites were included. Only 2 of them provided calculation of cardiovascular risk based on Framingham equation. The others proposed algorithms, guidelines, or general information on cardiovascular health. Most sites lacked details to ensure quality of information. Present search engines are inefficient to retrieve precise and valid information. Facing the inflation of medical information, a systematic approach to validate the quality of a site is mandatory. Application of Evidence Based Medicine concepts gives a solution for evaluation of internet-based medical information.

Cardiovascular Diseases↗

PubMed1999

The "mediator service", a component to ease the integration of medical applications in the SynEx framework.

Interoperability is a key issue and a long-term domain of research for distributed healthcare information systems. The European project SynEx provides an open and standard integration platform for both new and legacy medical applications. It allows the collaboration of distributed and heterogeneous healthcare records and services. It aims to provide access to Hospital Information Services, to remote sources of medical data and to medical knowledge, in a seamless way, hiding the distribution aspects and the heterogeneity of systems. In this project, the Medical Informatics Department of the Broussais University Hospital is responsible for the development of the "Mediator Service". It is a software component of the SynEx platform which is used as a "glue" mechanism to provide a flexible way to facilitate the interchange between any pair of systems, with different nomenclatures and data structures. The Mediator Service uses a generic model of mediators to create, through specialization, specific mediators for practical cases. Based on this model, it offers a C++ library to be used as the tool case by the programmers, to reduce the development effort. The use of XML as a powerful data interchange format and as a data structure descriptor is proposed and evaluated.

Computer Communication Networks↗

PubMed1998

IDEM: a Web application of case-based reasoning in histopathology.

Different software engineering and artificial intelligence methods can be used to design Internet retrieval of prototypical medical images. We used the case-based reasoning (CBR) approach to provide an 'intelligent' access to a collection of illustrated medical cases through the Internet. This paper presents a Web interface for the CBR system IDEM (image and diagnosis from examples in medicine) in the domain of breast pathology. Thanks to the definition of a similarity measure between the descriptions of cases we propose a flexible querying of the case-base and a quantitative browsing among cases through similarity links. The resemblance rates provided by the system argue for the quality and the relevancy of the retrieved data. The flexibility of the querying process is robust to missing information and could be adapted to a daily practice. The CBR approach is a promising method for a clinical relevant and an efficient retrieval of reference images and diagnosis clues through Internet.

Artificial Intelligence↗

PubMed1998

An overview of the effect of computer-assisted management of anticoagulant therapy on the quality of anticoagulation.

Risks and benefits of anticoagulant therapy depend directly of the quality of anticoagulation. We carried out a meta-analysis of published randomized trials to assess the overall effectiveness of computer-assisted prescription systems on the quality of anticoagulation. Randomized controlled trials were identified through electronic searches of the Medline database (1966-1997) and systematic analyses of the references of articles. Two investigators selected relevant papers and summarized data from the studies. The outcome variable was the proportion of days within the target range of anticoagulation. A pooled estimate of the common odds ratio of being in the target range and its confidence interval was obtained by the Mantel-Haenszel method. Nine trials having included 1336 patients were identified. Computer systems were based on a pharmacokinetic-pharmacodynamic model and a bayesian prediction method. Most of them concerned the oral anticoagulant warfarin. The global odds ratio of being in the target range was 1.29 [95% CI: 1.17-1.49], thus meaning that the use of a computer for anticoagulation optimization increased by 29% the proportion of visits where patients were appropriately treated. The proportion of clinical events was too low for allowing a summary analysis, but major hemorrhages tended to be less frequent among patients of the computer groups than among patients of the control groups (2.0 versus 3.9%). Evidence from randomized controlled trials supports the effectiveness of computer-aided anticoagulant prescription. Widespread use of these systems in ambulatory care could increase the benefit/risk ratio of anticoagulant treatment at a low cost.

Anticoagulants↗

PubMed1998

Implementation of a fuzzy prototype-based machine learning method to predict myocardial infarction from coronary angiography.

Formal knowledge on the predictive value of morphological angiographic factors is lacking to estimate the risk of myocardial infarction. This article presents a computer system for predicting the incidence of myocardial infarction from angiographic morphological descriptions of coronary lesions. The system includes two phases. The learning phase consists in extracting from a large database of described stenoses two classes represented by one or several fuzzy prototypes. One class corresponds to stenoses leading to infarction and the other to stenoses not leading to that event. The evaluation phase consists in classifying a stenosis according to its morphological characteristics in one of these two classes. The learning method is based on a fuzzy supervised Machine Learning algorithm that combines some aspects of the K-nearest neighbours clustering approach with a defined measure of similarity, and a prototype induction function from the most similar stenoses, taking into account their degree of typicality. The current results of the evaluation phase to correctly predicted X% stenoses for their risk of myocardial infarction. This article emphasizes the feasibility of the approach, however, the learning phase relies on some heuristics that should be validated to get a formal evaluation of the system.

Artificial Intelligence↗

PubMed1998

Case based diagnosis in histopathology of breast tumours.

Relevant knowledge and decision making process in histopathology is mostly included in typical pathological cases encountered by the expert. In this article we address the issue of exploiting this knowledge in the diagnosis process. We present the first steps of a Case-Based-Reasoning (CBR) system that uses the previously resolved pathological cases in order to facilitate decision making and diagnosis formulation of a new case. The work has been performed in two phases. Firstly, an object-oriented model of the domain was developed and 35 pathological cases of breast tumours were represented within this model. Secondly, the functional architecture of the CBR system was designed and the main procedure, the selection of similar cases, was achieved. The selection procedure is based on an original similarity measure that takes into account both semantic and structural resemblances and differences between the cases. A first evaluation of the system was performed on several cases of the data base. The interest of the CBR approach in situations where heuristic rules cannot be clearly defined is discussed.

Algorithms↗

PubMed1998

Computer-adjusted dosage of anticoagulant therapy improves the quality of anticoagulation.

OBJECTIVE: Risks and benefits of anticoagulant therapy depend directly of the quality of anticoagulation. We performed a meta-analysis of published randomized trials to assess the overall effectiveness of computer-based prescription systems on the quality of anticoagulation. DESIGN: Randomized controlled trials were identified through electronic searches of the Medline database (1966-1997) and systematic analyses of the references of articles. Two investigators selected relevant papers and summarized data from the studies. METHODS: The outcome variable was the proportion of days within the target range of anticoagulation. A pooled estimate of the common odds ratio of being in the target range and its confidence interval was obtained by the Mantel-Haenszel method. RESULTS: Seven trials having included 1217 patients were identified. Computer systems were based on a pharmacokinetic-pharmacodynamic model and a bayesian prediction method. Most of them concerned the oral anticoagulant warfarin. The global odds ratio of being in the target range was 1.58 [95% CI: 1.34-1.86], thus meaning that the use of a computer for anticoagulation optimization increased by 58% the proportion of visits where patients were appropriately treated. The proportion of clinical events was too low for allowing a summary analysis. CONCLUSION: Evidence from randomized controlled trials supports the effectiveness of computer-aided anticoagulant prescription. Diffusion of these systems in ambulatory care could increase the benefit/risk ratio of anticoagulant treatment at a low cost.

Anticoagulants↗

PubMed1998

OOMM--Object-Oriented Matrix Modelling: an instrument for the integration of the Brasilia Regional Health Information System.

The development of Health Information Systems is widely determined by the establishment of the underlying information models. An Object-Oriented Matrix Model (OOMM) is described which target is to facilitate the integration of the overall health system. The model is based on information modules named micro-databases that are structured in a three-dimensional network: planning, health structures and information systems. The modelling tool has been developed as a layer on top of a relational database system. A visual browser facilitates the development and maintenance of the information model. The modelling approach has been applied to the Brasilia University Hospital since 1991. The extension of the modelling approach to the Brasilia regional health system is considered.

Brazil↗

PubMed1998

Rationale and design considerations for a semantic mediator in health information systems.

Rapid development of community health information networks raises the issue of semantic interoperability between distributed and heterogeneous systems. Indeed, operational health information systems originate from heterogeneous teams of independent developers and have to cooperate in order to exchange data and services. A good cooperation is based on a good understanding of the messages exchanged between the systems. The main issue of semantic interoperability is to ensure that the exchange is not only possible but also meaningful. The main objective of this paper is to analyze semantic interoperability from a software engineering point of view. It describes the principles for the design of a semantic mediator (SM) in the framework of a distributed object manager (DOM). The mediator is itself a component that should allow the exchange of messages independently of languages and platforms. The functional architecture of such a SM is detailed. These principles have been partly applied in the context of the HELIOS object-oriented software engineering environment. The resulting service components are presented with their current state of achievement.

Computer Communication Networks↗

PubMed1998

A fuzzy classification system to predict renal artery restenosis after angioplasty.

Percutaneous transluminal angioplasty (PTRA) has emerged as a promising treatment for patients with renovascular hypertension. However, the benefit of this procedure is hampered by restenosis that frequently occurs within around 6 months after a successful angioplasty. This paper presents a fuzzy classification system based on a fuzzy pattern matching model that is being developed to evaluate the risk of short-term restenosis. First, identified classes are represented by fuzzy prototypes that take into account the imprecision of the criteria. Second, the system is applied to angiographic features of given stenoses and provides the membership degree of these stenosis to the two classes "short term restenosis" or "no restenosis". The fuzzy classifier's performances have been tested on twenty two patients who underwent balloon angioplasty in the context of a French multicenter randomized trial EMMA. With the fuzzy classifier, restenosis were predicted prospectively with 100% while its sensitivity is about 73%. The fuzzy classification system is expected to become a reliable tool to predict PTRA outcomes.

Angioplasty, Balloon↗

PubMed1998

Unified modeling language and design of a case-based retrieval system in medical imaging.

One goal of artificial intelligence research into case-based reasoning (CBR) systems is to develop approaches for designing useful and practical interactive case-based environments. Explaining each step of the design of the case-base and of the retrieval process is critical for the application of case-based systems to the real world. We describe herein our approach to the design of IDEM--Images and Diagnosis from Examples in Medicine--a medical image case-based retrieval system for pathologists. Our approach is based on the expressiveness of an object-oriented modeling language standard: the Unified Modeling Language (UML). We created a set of diagrams in UML notation illustrating the steps of the CBR methodology we used. The key aspect of this approach was selecting the relevant objects of the system according to user requirements and making visualization of cases and of the components of the case retrieval process. Further evaluation of the expressiveness of the design document is required but UML seems to be a promising formalism, improving the communication between the developers and users.

Artificial Intelligence↗