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Skin-brain signalling in itch reactions has been demonstrated with neuroimaging techniques showing specific brain activation. With positron emission tomography (PET), the itch model used must be adapted to technical and practical constraints. The technique of itch induction by histamine iontophoresis enables modulation of the sensation via the electrical charge applied. This itch model was validated on normal forearm skin of 56 subjects, with itch visual analogue scores peaking to approximately 1.0 cm after 3-4 min, falling to 0.2 cm at 15 min, with no influence of sex, zone, or order. Subsequently, the model was used in a PET study on 14 male volunteers, comparing histamine with physiological saline (control). The results show that the brain is able to discriminate these two conditions, with activated areas similar to those described previously, with, in addition, the anterior cingulate cortex and the insula being positively correlated with the intensity of the sensation.

Brain atrophy measured by magnetic resonance structural imaging has been proposed as a surrogate marker for the early diagnosis of Alzheimer's disease. Studies on large samples are still required to determine its practical interest at the individual level, especially with regards to the capacity of anatomical magnetic resonance imaging to disentangle the confounding role of the cognitive reserve in the early diagnosis of Alzheimer's disease. One hundred and thirty healthy controls, 122 subjects with mild cognitive impairment of the amnestic type and 130 Alzheimer's disease patients were included from the ADNI database and followed up for 24 months. After 24 months, 72 amnestic mild cognitive impairment had converted to Alzheimer's disease (referred to as progressive mild cognitive impairment, as opposed to stable mild cognitive impairment). For each subject, cortical thickness was measured on the baseline magnetic resonance imaging volume. The resulting cortical thickness map was parcellated into 22 regions and a normalized thickness index was computed using the subset of regions (right medial temporal, left lateral temporal, right posterior cingulate) that optimally distinguished stable mild cognitive impairment from progressive mild cognitive impairment. We tested the ability of baseline normalized thickness index to predict evolution from amnestic mild cognitive impairment to Alzheimer's disease and compared it to the predictive values of the main cognitive scores at baseline. In addition, we studied the relationship between the normalized thickness index, the education level and the timeline of conversion to Alzheimer's disease. Normalized thickness index at baseline differed significantly among all the four diagnosis groups (P < 0.001) and correctly distinguished Alzheimer's disease patients from healthy controls with an 85% cross-validated accuracy. Normalized thickness index also correctly predicted evolution to Alzheimer's disease for 76% of amnestic mild cognitive impairment subjects after cross-validation, thus showing an advantage over cognitive scores (range 63–72%). Moreover, progressive mild cognitive impairment subjects, who converted later than 1 year after baseline, showed a significantly higher education level than those who converted earlier than 1 year after baseline. Using a normalized thickness index-based criterion may help with early diagnosis of Alzheimer's disease at the individual level, especially for highly educated subjects, up to 24 months before clinical criteria for Alzheimer's disease diagnosis are met.

Whereas many studies have considered the role of attention in prospective timing, fewer have established relations between movement complexity and prospective timing. The present study aims at assessing to what extent motion complexity interferes with prospective timing and at delineating a neuropsychophysical plausible model. We have thus designed a visual paradigm presenting stimuli in sequential pairs (reference comparison interval). Stimuli are motionless or moving according to different complexities, and stimulus complexities are intermixed within each pair. To prevent a possible attention-sharing effect, no concurrent task was required. Our study suggests that movement complexity is a key component of duration perception, and that the relative judgement of durations depends on spatio-temporal features of stimuli. In particular, it shows that movement complexity can bias subjects' perception and performance, and that subjects detect that comparison intervals are longer than reference before their end. In the discussion, we advocate that the classical internal clock model cannot easily account for our results. Consequently, we propose a model for time perception, based on a parallel processing between comparison interval perception and the reconstruction of the reference duration.

The concept of picture archiving and communication system (PACS) appeared in 1982. Twelve years later most PACS prototypes still do not satisfy the medical community requirements: too much emphasis has been put on technical solutions and little effort devoted to the management of images itself. A common approach to this problem is needed more than ever to allow cost-effective systems to be developed. Modelling is a way to reach this objective, and the MIMOSA topic within the AIM/EurlPACS project aims at defining such a model of medical image management. This paper presents the MIMOSA approach with the three underlying constraints, i.e. genericity, implementation independence and performance. The MIMOSA group is building three interrelated models: a data model, a functional model and a dynamic model. However, in this report we focus only on the functional model, and explain how it was abstracted from various clinical scenarios in the first phase of the project. The availability level concept is introduced as a customizable and implementation independent solution to the problem of managing the delay of access to the information. The so-called contextual diagram and the acquisition of a new examination which are two representative parts of the model are detailed. The validation aspects and the relationships to projects working on the management of patient records are addressed as a conclusion.

grey matter (GM) probability in the MTL were obtained. Neuropsychological testing was performed at baseline for all subjects, and during follow-up between 1-3.5 years in MCI patients. Conversion to AD was defined based upon clinical and neuropsychological evaluation and change in Clinical Dementia Rating (CDR) scale score from 0.5 to 1.0. Subjects were reclassified to four cognitive status levels: 1 control, 2 MCI-Nonconverter, 3 MCI-Converter, and 4 AD. An ordinal regression model was created with MTL structural and PMC fMRI measures, age and MMSE as the independent variables. Results: Both imaging and follow-up data were available in 32 MCI subjects, 10 of whom converted to AD (total sample 28 controls, 22 MCI-Nonconverters, 10 MCI-Converters, and 13 AD). In our regression model, the main effects of all four factors were statistically significant (p 0.05), independent of one another. Contributions to model variance (highest to lowest) were as follows: MTL GM probability, MMSE, Age, and PMC signal change. Conclusions: PMC deactivation and MTL GM probability measures contribute independently to diagnostic classification, including prognosis in MCI patients. Combined use of structural and functional MRI information may serve as adjuncts to neuropsychological testing in early identification and monitoring of disease progression.

The T1 head template model used in Statistical Parametric Mapping Version 2000 (SPM2), was segmented into five layers (scalp, skull, CSF, grey and white matter) and implemented in 2 mm voxels. We designed a resistor mesh model (RMM), based on the finite volume method (FVM) to simulate the electrical properties of this head model along the three axes for each voxel. Then, we introduced four dipoles of high eccentricity (about 0.8) in this RMM, separately and simultaneously, to compute the potentials for two sets of conductivities. We used the direct cortical imaging technique (CIT) to recover the simulated dipoles, using 60 or 107 electrodes and with or without addition of Gaussian white noise (GWN). The use of realistic conductivities gave better CIT results than standard conductivities, lowering the blurring effect on scalp potentials and displaying more accurate position areas when CIT was applied to single dipoles. Simultaneous dipoles were less accurately localized, but good qualitative and stable quantitative results were obtained up to 5% noise level for 107 electrodes and up to 10% noise level for 60 electrodes, showing that a compromise must be found to optimize both the number of electrodes and the noise level. With the RMM defined in 2 mm voxels, the standard 128-electrode cap and 5% noise appears to be the upper limit providing reliable source positions when direct CIT is used. The admittance matrix defining the RMM is easy to modify so as to adapt to different conductivities. The next step will be the adaptation of individual real head T2 images to the RMM template and the introduction of anisotropy using diffusion imaging (DI).

Neuroimaging studies of reading converge to suggest that linguistically elementary stimuli are confined to the activation of bilateral posterior regions, whereas linguistically complex stimuli additionally recruit left hemispheric anterior regions, raising the hypotheses of a gradual bilateral-to-left and a posterior-to-anterior recruitment of reading related areas. Here, we tested these two hypotheses by contrasting a repertoire of eight categories of stimuli ranging from simple orthographic-like characters to words and pseudowords in a single experiment, and by measuring BOLD signal changes and connectivity while 16 fluent readers passively viewed the stimuli. Our results confirm the existence of a bilateral-to-left and posterior-to-anterior recruitment of reading related areas, straightforwardly resulting from the increase in stimuli's linguistic processing load, which reflects reading processes: visual analysis, orthographic encoding and phonological decoding. Connectivity analyses strengthened the validity of these observations and additionally revealed an enhancement of the left parieto-frontal information trafficking for higher linguistic processing. Our findings clearly establish the notion of a gradual spatio-functional recruitment of reading areas and demonstrate, to the best of our knowledge, the first evidence of a robust and staged link between the level of linguistic processing, the spatial distribution of brain activity and its information trafficking.

Journée spéciale du GDR STIC Santé-Inserm; Le projet Neurobase a pour objectif d'établir les conditions permettant de fédérer au travers d'Internet des bases d'informations en neuroimagerie, situées dans différents centres d'expérimentation, cliniques neurologiques ou de recherche en neurosciences cognitives. Ce projet consistera à spécifier comment relier et accéder à des bases d'informations en neuroimagerie par la définition d'une architecture informatique permettant l'accès et le partage de résultats d'expérimentations ou bien encore de méthodes de traitement des données au sein d'un même site ou entre sites différents. Cela permettra par exemple au sein de ces bases d'informations la recherche de résultats similaires, la recherche d'images contenant des singularités ou encore des recherches transversales de type "fouille de données" pour mettre en évidence d'éventuelles régularités.

Currently, various data formats are widely used for medical imags, e.g. DICOM for exchange through network and storage media, and INTERFILE for image exchange in nuclear medicine. These formats are only able partly to solve problems arising in accessing and handling imags. To solve such problems, an ontology dedicated to the description of data and knowledge involved in the handling and the management of medical images has been designed. The ontology offers a semantic frame of reference to which manipulation tools can refer. It considers various point of view on the data, related to the context of production, the content,and the data quality. It supports several levels of abstraction, going from a declarative level related to the examination type to the implementation level. Moreover, the ontology provides mechanisms allowing the creation and the description of new entities. It can, thus, act as an intermediate language ensuring accurate reuse of the entities. This paper, which presents work in progress, is focused on the description of the ontology and points out how to use it for the description of and the access to DICOM or INTERFILE entities, and for the extension of the DICOM or INTERFILE dictionaries, by adding new entities, in order to describe complex relationships between images.

In medical imaging, many methods of irreversible compression have been studied. However, none of them has been adopted as a standard, probably because of the lack of agreement regarding what is meant by 'acceptable' for an irreversible compression scheme. Among the numerous evaluation studies which have been performed, few only involved a psychovisual approach, and it is unsafe to draw definite conclusion from the reported result. The purpose of this work was to determine the importance of intra and inter observer variability in the psychovisual evaluation of irreversible compression methods for a very specific evaluation protocol involving digitized images of breast parenchyma and imags simulating breast parenchyma using a fractal model. the compression methods to be evaluated were JPEG and Embedded Zerotree Wavelet. Six radiologists had to determine whether each image had been compressed and decompressed. ROC analysis was performed to characterize the performance in compression detection. The large intra and inter observer variability observed in the detection of compression underlines the difficulty of determining an 'acceptable' scheme of irreversible compression in medical imaging in general, and bring the approval of irreversible compression schemes into question.

Evaluations of procedures in medical image processing are notoriously difficult and often unconvincing. From a detailed bibliographic study, we analyzed the way evaluation studies are conducted and extracted a number of entities common to any evaluation protocol. From this analysis, we propose here a generic evaluation model (GEM). The GEM includes the notion of hierarchical evaluation, identifies the components which have always to be defined when designing an evaluation protocol and shows the relationships that exist between these components. By suggesting rules applying to the different components of the GEM, we also show how this model can be used as a first step towards guidelines for evaluation.

Medical imaging data carry information which may be morphological or functional, and qualitative (e.g., labelling of zones) or quantitative (e.g., model identification). This information may be used in clinical practice or in fundamental, clinical or cognitive research. The information may thus be used in diagnostics, therapeutic follow-up, research, training, teaching, maintenance or in quality control.

Our objective is to offer clinicians wider access to evolving medical image processing (MIP) techniques, crucial to improve assessment and quantification of physiological processes, but difficult to handle for non-specialists in MIP. Based on artificial intelligence techniques, our approach consists in the development of a knowledge-based program supervision system, automating the management of MIP libraries. It comprises a library of programs, a knowledge base capturing the expertise about programs and data and a supervision engine. It selects, organizes and executes the appropriate MIP programs given a goal to achieve and a data set, with dynamic feedback based on the results obtained. It also advises users in the development of new procedures chaining MIP programs.. We have experimented the approach for an application of factor analysis of medical image sequences as a means of predicting the response of osteosarcoma to chemotherapy, with both MRI and NM dynamic image sequences. As a result our program supervision system frees clinical end-users from performing tasks outside their competence, permitting them to concentrate on clinical issues. Therefore our approach enables a better exploitation of possibilities offered by MIP and higher quality results, both in terms of robustness and reliability.

The paper presents the medical image database developed for use in the methodological research environment and in the laboratory clinical environment, designed to be capable of being interfaced to an image processing system. This database is intended to solve the numerous problems due to the complexity—multidimensionality and multimodality—of medical images. These problems are posed in terms of management, archiving, structuring and accessing of this archive, and specification of the interfaces with users and with image processing systems. Solving these problems involves making a formal description of the image and the data associated with the image, while taking into account the specifics of medical imaging. The kernel which contains this description allows the physical architecture of the management and archiving system to be decoupled from its logical architecture. This decoupling is essential in order to automate the recording of new data, the automatic reorganization of the system schema in the event of change in the system environment, and to help in consulting the database.

The clinical use of image processing requires both medical knowledge and expertise in image processing techniques. We have designed a knowledge-based interactive quantification support system (IQSS) to help the medical user in the use and evaluation of medical image processing, and in the development of specific protocols. As the user proceeds according to a heuristic and intuitive approach, our system is meant to work according to a similar behavior. At the basis of the reasoning of our monitoring system, there are the semantic features of an image and of image processing. These semantic features describe their intrinsic properties, and are not symbolic description of the image content. Their obtention requires modeling of medical image and of image processing procedures. Semantic interpretation function gives rules to obtain the values of the semantic features extracted from these models. Then, commonsense compatibility rules yield to compatibility criteria which are based on a partial order (a subsumption relationship) on image and image processing, enabling a comparison to be made between data available to be processed and appropriate image processing procedures. This knowledge-based approach makes IQSS modular, flexible and consequently well adapted to aid in the development and in the utilization of image processing methods for multidimensional and multimodality medical image quantification.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The purpose of this paper is i) to explain the need for a generic image model in medical imaging, ii) to describe under which conditions such a model can be built, and iii) to present the image model we have been developing during the last two years in the framework ofthe EurlPacs IMimosaproject ofthe ATM programme ofthe European Communities'. Several organisations are in the process of defining communication standards (in particular DICOM) for medical imaging, as successfully demonstrated during the last RNSA meeting. Such a standard is an absolute necessity for implementing PACS, since it provides a framework to exchange image information produced by multi-vendor acquisition devices. Unfortunately such a standard is not sufficient to build a clinically useful PACS. One must also describe how data are organised in medical imaging, to allow end users (clinicians) to understand image information. This is the aim of the EurlPacs I Mimosaproject. The basic assumption of this work is that there is a common denominator in the way clinicians "understand" medical images even though local particularisms may hide it. Consequently our model aims at describing medical images in a way general enough to allow for a generic description, while providing facilities to describe local characteristics. Our approach makes use of a fairly standard modelling technique : data model using NIAM, fimctional modelling2 and organisational modelling. It turns out that local particularisms can be described at the dynamic level or even at the implementation level which is not considered in the formal model, such that a generic model can be defined. Moreover communication standards such as DICOM2 can be used within our model to describe how image data are actually organised as files to be transferred between PACS nodes. In this regard there is no overlap between the Mimosa model and communication standards. We consider three levels for the data model : an examination context which describes high level objects such as patient folder, request, report, a PACS model which describes the resources (network, acquisition devices, archives, image workstation) involved in image manipulation, and an image kernel which describes images. The examination context essentially contains attributes allowing HIS/RIS to monitor and control medical image information. They constitute most of the information exchanged between PACS and HIS/RIS. The PACS model addresses issues such as network performances, local storage capacity to provide image information in the right place at the right time. The image kernel specifies image attributes able to accurately define how images are acquired, processed, interpreted and used during diagnostic and/or therapeutic processes. It is clear that this model must be generic and modality independent5 to encompass any and every use of medical images, and precise enough to allow for their efficient use (in particular for multidimensional and multimodality data). Consequently this model may seem complex and significantly differs from commonly used image models. However it proved to be able to describe all examples against which it was tested contrary to other models. Because of its apparent complexity and because of its potential power, we think it is worth devoting a paper to its description. In section 2 we explain why such a model is required. In section 3 we describe the core of the model : the "image object" and its various components : Formal aspects, Version, Representation, Logical Files and Copies. In the same section we present two important related concepts : Image generator and Reference position. In section 4 we show how image objects can be grouped to become meaningful at the examination context level.

A new statistical approach for Factor Analysis of Medical Image Sequences (FAMIS) is proposed. It leads to the optimal metric to be used in the orthogonal and oblique analysis steps of FAMIS. It is shown that this metric depends on the statistical model related to the image acquisition process and we derived its expression for nuclear medicine and magnetic resonance imaging. A scintigraphic dynamic study illustrates the method. We discuss the normalization induced by this optimal metric in comparison with other normalizations.

The clinical use of image analysis requires on the one hand a knowledge of pathology, physiology and other medical fields, and on the other hand expertise in image processing techniques. Because of the increasing complexity, these techniques are not often employed by clinical users, who want to focus on interpreting results rather than focusing on the choice of a specific package, the way it operates and the underlying processes. Thus it is of prime importance to clinical users to have at their disposal a system which can accept their clinical knowledge as input, then convert it into an appropriate mathematical language, process it, and finally return the results to them in a clinically intelligible fashion. The concept of an 'intelligent system' interface between medical users and applications has been developed, which we have termed an Interactive Quantitation Support System (IQSS). Such a system translates clinical knowledge into symbolic descriptions and transmits them to the software application. IQSS manages the dialogue between user and application, as well as error handling. A prototype of the user interface has been developed based on a client/server architecture and a data-oriented environment. Early in its development, this IQSS has been tested in prototype form to perform a three-dimensional registration of multimodality images.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

PACS would allow sharing of knowledge about medical images among a large number of biomedical actors (acquisition, consultation, administrative and archiving systems), but each one has its own viewpoint on this knowledge.

The work reported in this paper has been carried out in the framework of the EURIPACS/MIMOSA AIM project. This paper reports about a preliminary review of PACS users requirements: it stresses some difficulties encountered in discussions with the users and explains how we tried to overcome them. The result of this analysis is presented and briefly discussed.

Due to improvements in technology of information processing systems, more and more valuable information is generated each day, in biomedical institutions. Thus, providing a mutual understanding between all users is vital in health care information systems, either paper or computer based. This state of interoperability can be reached by designing an open environment for managing, exchanging and distributing biomedical images and the related informations. PACS attempt to overcome this challenge. Until now, they are only defined in terms of data processing tools, and not in terms of users' requirements. Moreover, border lines between PACS and HIS or RIS, are not well specified. MIMOSA team is using a quite different approach, more suitable to fulfill interoperability. This approach is not centered around any implementation considerations, but takes into account user's needs, i.e., the goal, the behaviour and the dynamics of biomedical images. Consequently, it is more comprehensive and integrates all data and operations involved in biomedical image handling, whatever their origin (image sources, HIS, RIS) is.

Objects to be handled in medical image processing include large value arrays (curves, images, ...) and tightly associated data (patient's identification, conditions of acquisition, ...). Their validation constraints and structure are complex because they are dependent on the source and processing. The number of objects may change as new generators (source or processing) emerge. These objects and the constraints are formally described (BADAOUI9O), according to the following concepts: the basic type (for atomic attributes), the constructed type (for the multi-attribute features), the class type (for the complex entities and constraints) leading to a non-normalized relational model. This model, implemented on top of an RDBMS (Relational Data Base Management System) by way of a dictionary (metadatabase), defines entirely the base by intention and monitors its evolution. A tool associated with this model sets up the bridge with the relational model.

In this paper, we take the standpoint of physicians (radiologists, clinicians, surgeons) to define the required content of medical image data bases, from the needs for retrieving images. We conclude that two main approaches (minimal and generalized) solutions are medically acceptable.

Resume Introduction L’imagerie par Resonance Magnetique anatomique est un candidat pour la detection precoce et le suivi longitudinal de la maladie d’Alzheimer a travers l’etude de l’atrophie cerebrale. Objectifs Les algorithmes permettant l’etude de l’atrophie cerebrale doivent etre testes pour eprouver leur capacite de localisation et de quantification en termes de robustesse et de precision. Methodes Nous avons developpe un algorithme permettant d’introduire, sur des images reelles, des atrophies de localisation et de quantification controlables. Nous avons simule differents degres d’atrophie sur douze images de sujets sains, puis teste un representant de chacune des deux grandes classes d’algorithmes de la litterature : VBM (detection voxel a voxel en analyse transverse de groupes) et SIENA (mesure du deplacement de la frontiere cerebrale en analyse individuelle longitudinale). Resultats Selon les parametrages utilises lors des tests statistiques, soit VBM n’a pas permis de detecter les atrophies simulees, soit la detection a ete entachee de nombreux faux positifs. SIENA a permis de calculer pour chaque atrophie un indice global. Cependant, cet indice a sous estime l’atrophie ; il etait de plus biaise par les pretraitements des images et presentait une forte variabilite entre individus. Discussion L’utilisation clinique fait appel a une methode fournissant une localisation et une quantification la plus locale possible de l’atrophie et presentant un parametrage simple. VBM souffre d’un parametrage complexe et ne permet que la localisation. SIENA permet la localisation et la quantification, mais cette derniere est globale, imprecise et variable entre individus. Conclusion Aucune des methodes testees n’est entierement adaptee aux besoins cliniques. Nous developpons donc une methode originale, basee sur l’epaisseur corticale, fournissant des informations quantitatives locales de l’atrophie.

Introduction La perception du temps est une faculte importante pour l’homme. Elle fait partie de la vie courante, permet de planifier, controler et realiser des actions dans un environnement en mouvement. Objectifs Dans notre etude nous cherchons a montrer, grâce a l’imagerie cerebrale (IRMf), la modulation, due a la presence de mouvement, de l’activation des aires impliquees dans la perception du temps. Methodes Des stimuli visuels, fixes (condition controle) ou en mouvement, etaient presentes par couple et le sujet devait estimer si la duree du second stimulus etait egale ou differente de celle du premier. Les sept sujets etaient de sexe feminin, droitiers, avec une moyenne d’âge de 24 ans (± 1,56 ans). Les donnees d’imagerie ont ete analysees avec le logiciel SPM. Nous avons choisi de contraster les conditions avec mouvement a la condition controle. Resultats Nos resultats montraient que les conditions presentant du mouvement activaient les aires connues dans la perception du temps : aires corticales (cortex frontal, cortex parietal, aires motrices et aires cingulaires) et sous corticales (ganglions de la base et noyaux gris centraux). Le contraste condition avec mouvement versus condition fixe suractivait preferentiellement des zones sous corticales. Le jugement des sujets sur la duree d’un evenement etait aussi influence par la presence du mouvement. Discussion Les etudes sur la perception du temps montrent le role important des ganglions de la base. D’apres plusieurs auteurs, ils supporteraient le « pacemaker » du modele de l’horloge interne dont la frequence peut etre influencee par des elements exogenes. Les suractivations sous corticales peuvent donc etre expliquees par une influence du mouvement sur le rythme du pacemaker. Conclusion Nous rejoignons les etudes qui montrent que le rythme du pacemaker peut etre module par les caracteristiques du stimulus, ici le mouvement, influencant ainsi le jugement du sujet.

Transaxial tomoscintigraphy (or single-photon emission computerised tomography) was used to detect secondary deposits of carcinoma in 17 patients who had been injected with iodine-131-labelled monoclonal antibodies against carcinoembryonic antigen. Of 17 tumor sites studied by tomoscintigraphy 16 were detected (sensitivity 94%); five sites had a volume smaller than 10 cm3. Tomoscintigraphy also detected three unknown tumour deposits later confirmed by surgery or radiology. In contrast, when 21 tumour sites in the same patients were studied by rectilinear scintigraphy, only nine tumour sites were detected (sensitivity 43%), of which eight had a volume larger than 50 cm3.

We developed a biomedical image database (BDIM) which proposes a standardized representation of value arrays such as images and curves, and of their associated parameters, independently of their acquisition mode to make their transmission and processing easier. It includes three kinds of interactions, oriented to the users. The network concept was kept as a constraint to incorporate the BDIM in a distributed structure and we maintained compatibility with the ACR/NEMA communication protocol. The management of arrays and their associated parameters includes two distinct bases of objects, linked together via a gateway. The first one manages arrays according to their storage mode: long term storage on optionally on-line mass storage devices, and, for consultations, partial copies of long term stored arrays on hard disk. The second one manages the associated parameters and the gateway by means of the relational DBMS ORACLE. Parameters are grouped into relations. Some of them are in agreement with groups defined by the ACR/NEMA. The other relations describe objects resulting from processed initial objects. These new objects are not described by the ACR/NEMA but they can be inserted as shadow groups of ACR/NEMA description. The relations describing the storage and their pathname constitute the gateway. ORACLE distributed tools and the two-level storage technique will allow the integration of the BDIM into a distributed structure, Queries and array (alone or in sequences) retrieval module has access to the relations via a level in which a dictionary managed by ORACLE is included. This dictionary translates ACR/NEMA objects into objects that can be handled by the DBMS.(ABSTRACT TRUNCATED AT 250 WORDS)

The processing of medical images requires the handling of complex structured sets of elementary objects (images, curves,... and their associated parameters). Usually, an elementary object cannot be interpreted without information concerning the structure to which it belongs (e.g image sequences). Then it is necessary to consider the whole structure like an atomic semantic entity, object of an image data base. As specific tools are necessary to manage these objects, an object oriented handling system (OHS), part of our medical image data base project (BDIM), was developed to perform : i) the array storage management, ii) the interface between applications and the BDIM to have access to objects (create, update, delete...) and components (navigation inside object structures, access to arrays and parameters). The image handling system (IHS) decribed here is the user level part of the OHS. IHS allows the evolution of the data base environment by adding or updating acquisition and/or processing functionalities. To unify data access methods, the concept of logical file is introduced as a special class of BDIM objects. The logical file does not necessitate the use of a specific declaration for the different kinds of images because it is possible, for a desired processing , to have access to the only concerned data.

We present the results obtained from 53 hepatic tomoscintigrams (48 patients) that principally correspond to primary gastrointestinal cancers with possible hepatic metastases. We have tested this technique and extracted the most significant images from this relatively small number of patients.