Biomedical subjects

Bernard Gibaud

Publications and source records attributed to Bernard Gibaud.

8 recordsLinked to original sources

PubMed2005

From anatomic standardization analysis of perfusion SPECT data to perfusion pattern modeling: evidence of functional networks in healthy subjects and temporal lobe epilepsy patients.

RATIONALE AND OBJECTIVES: In the general context of perfusion pattern modeling from single-photon emission computed tomographic (SPECT) data, the purpose of this study is to characterize interindividual functional variability and functional connectivity between anatomic structures in a set of SPECT data acquired from a homogeneous population of subjects. MATERIALS AND METHODS: From volume of interest (VOI)-perfusion measurements performed on anatomically standardized SPECT data, we proposed to use correspondence analysis (CA) and hierarchical clustering (HC) to explore the structure of statistical dependencies among these measurements. The method was applied to study the perfusion pattern in two populations of subjects; namely, SPECT data from 27 healthy subjects and ictal SPECT data from 10 patients with mesio-temporal lobe epilepsy (MTLE). RESULTS: For healthy subjects, anatomic structures showing statistically dependent perfusion patterns were classified into four groups; namely, temporomesial structures, internal structures, posterior structures, and remaining cortex. For patients with MTLE, they were classified as temporomesial structures, surrounding temporal structures, internal structures, and remaining cortex. Anatomic structures of each group showed similar perfusion behavior so that they may be functionally connected and may belong to the same network. Our main result is that the temporal pole and lenticular nucleus seemed to be highly relevant to characterize ictal perfusion in patients with MTLE. This exploratory analysis suggests that a network involving temporal structures, lenticular nucleus, brainstem, and cerebellum seems to be involved during MTLE seizures. CONCLUSION: CA followed by HC is a promising approach to explore brain perfusion patterns from SPECT VOI measurements.

Adult↗

PubMed2005

Evaluation of methods to detect interhemispheric asymmetry on cerebral perfusion SPECT: application to epilepsy.

UNLABELLED: Detecting perfusion interhemispheric asymmetry in neurologic nuclear medicine imaging is an interesting approach to epilepsy. METHODS: This study compared 4 methods that detect interhemispheric asymmetries of brain perfusion in SPECT. The first (M1) was conventional side-by-side expert-based visual interpretation of SPECT. The second (M2) was visual interpretation assisted by an interhemispheric difference (IHD) volume. The last 2 were automatic methods: unsupervised analysis using volumes of interest (M3) and unsupervised analysis of the IHD volume (M4). Use of these methods to detect possible perfusion asymmetry was compared on 60 simulated SPECT datasets by controlling the presence and location of asymmetries. From the detection results, localization receiver operating characteristic curves were generated and areas under curves were estimated and compared. Finally, the methods were applied to analyze interictal SPECT datasets to localize the epileptogenic focus in temporal lobe epilepsies. RESULTS: This study showed an improvement in asymmetry detection on SPECT images with the methods using IHD volume (M2 and M4), in comparison with the other methods (M1 and M3). However, the most useful method for analyzing clinical SPECT datasets appeared to be visual inspection assisted by the IHD volume, since the automatic method using the IHD volume was less specific. CONCLUSION: The use of quantitative methods can improve performance in detection of perfusion asymmetry over visual inspection alone.

Adolescent↗

PubMed2003

Models of surgical procedures for multimodal image-guided neurosurgery.

Improvement of image guided surgery systems requires a better anticipation of the surgical procedure. This anticipation may be provided by a better understanding of surgical procedures and/or the use of information models related to neurosurgical procedures. We are introducing a generic model of surgical procedures in the context of multimodal image-guided craniotomies. The basic principle of the model is to break down the surgical procedure into a sequence of steps defining the surgical script. Each step is defined by an action; the model assigns to each surgical step a list of image entities extracted from multimodal preoperative images (anatomical and/or functional images) which are relevant to the performance of that particular step. The model has been built in two phases: creation and consolidation. Besides, a planning software prototype based on the generic model has been built. The resulting generic model is described by an UML class diagram and textual description. Some initial benefits of this approach can already be outlined: improvement of multimodal information management, enhancement of the preparation and the guidance of the surgical act.

Humans↗

PubMed2003

Interoperability and medical communication using "patient envelope"-based secure messaging.

The process of transmitting patient medical information between different healthcare parties involves harmonizing multiple elements: addresses, certificates, patient IDs, communication protocol, message format, and documents/EPR to be exchanged. Beyond the work done at the "information structure level" within CEN TC251, ISO TC215, HL7 and DICOM, it is necessary to focus on the "basic medical communication level." An original approach, based on the "Patient Envelope", has been developed and successfully implemented for Oncology. The operator of the National "Réseau Santé Social" is now proposing a new "secure messaging" service supporting the "Envelope"-based communication. The authors are actively involved in standardization organizations' works, including EDI Santé, DICOM, IETF, and ISO TC 215. The current "envelope" format is compatible with all the e-mail clients. It will evolve to be based on the ebXML envelope, extended with a "medical header" containing HL7/EHRCOM Data Types and C-METS/GPICs. This document describes the results from a 3-year experience, as well as the different steps included in the project.

Computer Security↗

PubMed2003

Modelling dependencies between relations to ensure consistency of a cerebral cortex anatomy knowledge base.

A symbolic model of anatomy that could be used in various contexts is a key feature. However, explicitly representing anatomy requires managing many specialisation, part-whole and topological relationships. Furthermore, we notice dependencies between some of them. These dependencies have to be taken into account in order to insure both intrinsic and incremental consistency of the model. Our approach is composed of three steps. First, we define the relationships between anatomical concepts by relationships between the space region they take up or the portion of matter they are made of. Second, we use these definitions and properties of spatial and matter relationships to infer dependencies between anatomical relationships. Eventually, we apply these dependencies to the set of independent anatomical relationships to automatically generate all the dependent relationships. This method was used to maintain an anatomical model of the frontal, temporal, parietal and occipital regions of the cerebral cortex. For 113 concepts, 221 of the 370 relationships could be automatically generated. The more the number of concepts increase, the more pertinent the method appears.

Artificial Intelligence↗

PubMed2003

Re-use of a multi-purpose knowledge corpus on cortex anatomy for educational purposes.

This work aims at producing a software package to be used during "hands on" sessions about anatomy, focusing on gross brain cortex anatomy. Emphasis is put on the 3D shape and topology of the cortex anatomical structures, described both using numeric data (derived from MRI images) and symbolic data ("part-whole", topological realtions). "Spatial" and "semantic" synchronisation are provided to connect the numeric and symbolic knowledge. The knowledge corpus includes both 3D data showing the sulci, the gyri and the 3D MRI data, and a general purpose symbolic knowledge base of brain cortex anatomical features. Implementation is achieved using web technologies.

Anatomy↗

PubMed2002

Integration of sulcal and functional information for multimodal neuronavigation.

OBJECT: The authors present the use of cortical sulci, segmented from magnetic resonance (MR) imaging, and functional data from functional (f)MR imaging and magnetoencephalography (MEG) in the image-guided surgical management of lesions adjacent to the sensorimotor cortex. METHODS: In an initial set of 11 patients, sulci near lesions were automatically segmented from MR imaging data sets, then MEG and fMR imaging examinations were performed. Relevant functional information was preoperatively interpreted and selected from MEG and fMR imaging and subsequently transferred to the navigation system for selected sulci. A neuronavigation system consisting of a surgical microscope with enhanced reality overlay display was used. Data were displayed as contours on the cut-plane images of a stereotactic workstation and as contours on the overlay screen of the head-up display within the optical path of the right eyepiece of the surgical microscope. CONCLUSIONS: This method, in which both sulcal and functional mapping are used for surgery planning and neuronavigation, provides helpful information. It is a promising procedure for the treatment of patients who harbor lesions in areas around the eloquent cortex.

Adult↗

PubMed2002

Towards a sharable numeric and symbolic knowledge base on cerebral cortex anatomy: lessons learned from a prototype.

We propose a knowledge base that combines numeric and symbolic knowledge about sulco-gyral brain cortex. This knowledge base is implemented using Web technologies. It is intended to be easily reusable in various application contexts such as teaching, decision support in neurosurgery and sharing of neuroimaging data for research purposes. Our analysis shows that (1) a formal representation of taxonomy and mereotopology, and (2) use of identity criteria to represent symbolic concepts, are needed to serve those applications.

Artificial Intelligence↗