Mapping the asynchrony of cortical maturation in the infant brain: A MRI multi-parametric clustering approach.

While the main neural networks are in place at term birth, intense changes in cortical microstructure occur during early infancy with the development of dendritic arborization, synaptogenesis and fiber myelination. These maturational processes are thought to relate to behavioral acquisitions and the development of cognitive abilities. Nevertheless, in vivo investigations of such relationships are still lacking in healthy infants. To bridge this gap, we aimed to study the cortical maturation using non-invasive Magnetic Resonance Imaging, over a largely unexplored period (1-5 post-natal months). In a first univariate step, we focused on different quantitative parameters: longitudinal relaxation time (T1), transverse relaxation time (T2), and axial diffusivity from diffusion tensor imaging (λ//) These individual maps, acquired with echo-planar imaging to limit the acquisition time, showed spatial distortions that were first corrected to reliably match the thin cortical ribbon identified on high-resolution T2-weighted images. Averaged maps were also computed over the infants group to summarize the parameter characteristics during early infancy. In a second step, we considered a multi-parametric approach that leverages parameters complementarity, avoids reliance on pre-defined regions of interest, and does not require spatial constraints. Our clustering strategy allowed us to group cortical voxels over all infants in 5 clusters with distinct microstructural T1 and λ// properties The cluster maps over individual cortical surfaces and over the group were in sound agreement with benchmark post mortem studies of sub-cortical white matter myelination, showing a progressive maturation of 1) primary sensori-motor areas, 2) adjacent unimodal associative cortices, and 3) higher-order associative regions. This study thus opens a consistent approach to study cortical maturation in vivo.

Interoperable atlases of the human brain.

The last two decades have seen an unprecedented development of human brain mapping approaches at various spatial and temporal scales. Together, these have provided a large fundus of information on many different aspects of the human brain including micro- and macrostructural segregation, regional specialization of function, connectivity, and temporal dynamics. Atlases are central in order to integrate such diverse information in a topographically meaningful way. It is noteworthy, that the brain mapping field has been developed along several major lines such as structure vs. function, postmortem vs. in vivo, individual features of the brain vs. population-based aspects, or slow vs. fast dynamics. In order to understand human brain organization, however, it seems inevitable that these different lines are integrated and combined into a multimodal human brain model. To this aim, we held a workshop to determine the constraints of a multi-modal human brain model that are needed to enable (i) an integration of different spatial and temporal scales and data modalities into a common reference system, and (ii) efficient data exchange and analysis. As detailed in this report, to arrive at fully interoperable atlases of the human brain will still require much work at the frontiers of data acquisition, analysis, and representation. Among them, the latter may provide the most challenging task, in particular when it comes to representing features of vastly different scales of space, time and abstraction. The potential benefits of such endeavor, however, clearly outweigh the problems, as only such kind of multi-modal human brain atlas may provide a starting point from which the complex relationships between structure, function, and connectivity may be explored.

Markov models for fMRI correlation structure: Is brain functional connectivity small world, or decomposable into networks?

Correlations in the signal observed via functional Magnetic Resonance Imaging (fMRI), are expected to reveal the interactions in the underlying neural populations through hemodynamic response. In particular, they highlight distributed set of mutually correlated regions that correspond to brain networks related to different cognitive functions. Yet graph-theoretical studies of neural connections give a different picture: that of a highly integrated system with small-world properties: local clustering but with short pathways across the complete structure. We examine the conditional independence properties of the fMRI signal, i.e. its Markov structure, to find realistic assumptions on the connectivity structure that are required to explain the observed functional connectivity. In particular we seek a decomposition of the Markov structure into segregated functional networks using decomposable graphs: a set of strongly-connected and partially overlapping cliques. We introduce a new method to efficiently extract such cliques on a large, strongly-connected graph. We compare methods learning different graph structures from functional connectivity by testing the goodness of fit of the model they learn on new data. We find that summarizing the structure as strongly-connected networks can give a good description only for very large and overlapping networks. These results highlight that Markov models are good tools to identify the structure of brain connectivity from fMRI signals, but for this purpose they must reflect the small-world properties of the underlying neural systems.

Robust clustering of massive tractography datasets.

This paper presents a clustering method that detects the fiber bundles embedded in any MR-diffusion based tractography dataset. Our method can be seen as a compressing operation, capturing the most meaningful information enclosed in the fiber dataset. For the sake of efficiency, part of the analysis is based on clustering the white matter (WM) voxels rather than the fibers. The resulting regions of interest are used to define subset of fibers that are subdivided further into consistent bundles using a clustering of the fiber extremities. The dataset is reduced from more than one million fiber tracts to about two thousand fiber bundles. Validations are provided using simulated data and a physical phantom. We see our approach as a crucial preprocessing step before further analysis of huge fiber datasets. An important application will be the inference of detailed models of the subdivisions of white matter pathways and the mapping of the main U-fiber bundles.

A group model for stable multi-subject ICA on fMRI datasets.

Spatial Independent Component Analysis (ICA) is an increasingly used data-driven method to analyze functional Magnetic Resonance Imaging (fMRI) data. To date, it has been used to extract sets of mutually correlated brain regions without prior information on the time course of these regions. Some of these sets of regions, interpreted as functional networks, have recently been used to provide markers of brain diseases and open the road to paradigm-free population comparisons. Such group studies raise the question of modeling subject variability within ICA: how can the patterns representative of a group be modeled and estimated via ICA for reliable inter-group comparisons? In this paper, we propose a hierarchical model for patterns in multi-subject fMRI datasets, akin to mixed-effect group models used in linear-model-based analysis. We introduce an estimation procedure, CanICA (Canonical ICA), based on i) probabilistic dimension reduction of the individual data, ii) canonical correlation analysis to identify a data subspace common to the group iii) ICA-based pattern extraction. In addition, we introduce a procedure based on cross-validation to quantify the stability of ICA patterns at the level of the group. We compare our method with state-of-the-art multi-subject fMRI ICA methods and show that the features extracted using our procedure are more reproducible at the group level on two datasets of 12 healthy controls: a resting-state and a functional localizer study.

[External dacryocystorhinostomy under local anesthesia and sedation]. / Les dacryocystorhinostomies par voie externe sous anesthésie locale et sédation.

INTRODUCTION: External dacryocystorhinostomy (DCR) surgery is highly advantageous in that it can be performed under local anesthesia associated with sedation. We aimed at verifying the efficiency of the anesthesia, studying the general behavior of the patient and the quality of the surgery. PATIENTS AND METHODS: A prospective study of a local anesthetic protocol associated with sedation was conducted in our Oculoplastic Department on 34 patients (71.5+/-8.3 years of age) between may 2007 and march 2008. The anesthetic protocol consisted of blocking four nerves based on the analysis of the anatomy of facial innervation. The including criteria were patient antecedents such as arterial hypertension, cardiac or lung problems, diabetes, and no contraindications for local anesthesia. The hemodynamic constants, variability of the Ramsay score, and complications such as bleeding or pain were studied. The progress of the surgery was simultaneously evaluated by the patients, anesthesiologists, and surgeons. RESULTS: Both the hemodynamic constants and the Ramsay score remained stable intra- and postoperatively. In addition, the visual analog scale (VAS) scores remained low. Both surgeon and patient satisfaction was excellent (88.4 % of the patients declared that they were ready to choose the same anesthetic protocol if new surgery were to be performed). The surgery's success rate was 79.3 % (no watering at 3 months) versus 82 % for the patients operated under general anesthesia. CONCLUSION: The protocol of local anesthesia associated with sedation for external DCR is therefore safe and efficient.

French Infobutton: an academic and business perspective.

Infobuttons are context-specific links between clinical information systems and other online information resources. The objective of this study is to describe a French Infobutton, which will be sold in the French-speaking Health Information market.

Cataloguing and displaying Web feeds from French language health sites: a Web 2.0 add-on to a health gateway.

Among the numerous new functionalities of the Internet, commonly called Web 2.0, Web syndication illustrates the trend for better and faster information sharing. Web feeds (a.k.a RSS feeds), which were used mostly on weblogs at first, are now also widely used in academic, scientific and institutional websites such as PubMed. As very few French language feeds were listed or catalogued in the Health field by the year of 2007, it was decided to implement them in the quality-controlled health gateway CISMeF ([French] acronym for Catalogue and Index of French Language Health Resources on the Internet). Furthermore, making full use of the nature of Web syndication, a Web feed aggregator was put online in to provide a dynamic news gateway called "CISMeF actualités" (http://www.chu-rouen.fr/actualites/). This article describes the process to retrieve and implement the Web feeds in the catalogue and how its terminology was adjusted to describe this new content. It also describes how the aggregator was put online and the features of this news gateway. CISMeF actualités was built accordingly to the editorial policy of CISMeF. Only a part of the Web feeds of the catalogue were included to display the most authoritative sources. Web feeds were also grouped by medical specialties and by countries using the prior indexing of websites with MeSH terms and the so-called metaterms. CISMeF actualités now displays 131 Web feeds across 40 different medical specialities, coming from 5 different countries. It is one example, among many, that static hypertext links can now easily and beneficially be completed, or replaced, by dynamic display of Web content using syndication feeds.

Use of super-concepts to customize electronic medical records data display.

Patient medical record systems (MRS) merely offer static applications, in which mostly unstructured text is linked to coded data. In these applications the more common presentation is a time oriented one, which does not allow easily for data and information retrieval. Concept oriented views based on supper-concepts (metaterms) initially defined in CISMeF to optimize Web medical search, was implemented in our MRS as specialties views. This work shows that these terminological tools are able to facilitate information retrieval.

Level of evidence as a future gold standard for the content quality of health resources on the internet.

OBJECTIVE: An assessment of the quality of health information on the Internet is an absolute necessity. In this study 'sensitive' information was defined as information found in documents published on the Internet, which could be used in a medical decision. For sensitive information, the main criterion chosen for the quality of the information was an indication of the level of evidence. A survey was conducted using the CISMeF health catalogue to assess how often a score of the level of evidence is mentioned in the information accessible on the Internet in French-language health resources. METHODS: Since 1999, members of the CISMeF team have systematically been searching for all documents containing 'sensitive' information and verifying whether the level of evidence was explicitly indicated as a score at least once in the document. RESULTS: As of June 2001, 10,190 resources were included in CISMeF; including 2964 textual 'sensitive' resources (29.1%). Out of all these resources, only 4.7% (95% confidence interval: 4.0 - 5.5%) indicated the level of evidence. A statistically significant difference in the prevalence of indicating the level of evidence according to resource types (e.g., 18.1% for guidelines compared to 0.0% for teaching material), year of publication (almost three times greater in 1997-2001 compared with 1990-1996) and publishers was observed. CONCLUSION: As the number of people accessing the growing amount of information on the Internet is increasing daily, publishers have an ethical obligation to inform their readers about the validity of 'sensitive' information their sites contain. However, the vast majority of the French language Internet resources that were surveyed do not mention a score of the level of evidence for their sensitive information.

A search tool based on 'encapsulated' MeSH thesaurus to retrieve quality health resources on the internet.

In the year 2001, the Internet has become a major source of health information for the health professional and the Netizen. The objective of Doc' CISMeF (D'C) was to create a powerful generic search tool based on a structured information model which 'encapsulates' the MeSH thesaurus to index and retrieve quality health resources on the Internet. To index resources, D'C uses four sections in its information model: 'meta-term', keyword, subheading, and resource type. Two search options are available: simple and advanced. The simple search requires the end-user to input a single term or expression. If this term belongs to the D'C information structure model, it will be exploded. If not, a full-text search is performed. In the advanced search, complex searches are possible combining Boolean operators with meta-terms, keywords, subheadings and resource types. D'C uses two standard tools for organising information: the MeSH thesaurus and the Dublin Core metadata format. Resources included in D'C are described according to the following elements: title, author or creator, subject and keywords, description, publishers, date, resource type, format, identifier, and language.

Doc'CISMEF: a search tool based on "encapsulated" MeSH thesaurus.

In the year 2000, the Internet became a major source of health information for the health professional and the Netizen. The objective of Doc'CISMeF (D'C) was to create a powerful generic search tool based on an structured information model which â encapsulates' the MeSH thesaurus to index and retrieve quality health resources on the Internet. To index resources, D'C uses four sections in its information model: 'meta-term', keyword, subheading, and resource type. Two search options are available: simple and advanced. The simple search requires the end-user to input a single term or expression. If this term belongs to the D'C information structure model, it will be exploded. If not, a full-text search is performed. In the advanced search, complex searches are possible combining Boolean operators with meta-terms, keywords, subheadings and resource types. D'C uses two standard tools for organising information: the MeSH thesaurus and the Dublin Core metadata format. Resources included in D'C are described according to the following elements: title, author or creator, subject and keywords, description, publisher, date, resource type, format, identifier, and language.

Reading factor: a bibliometric tool to manage a virtual library.

UNLABELLED: Among the many bibliometric criteria used to evaluate biomedical journals, the impact factor is the most commonly used. Despite its limitations, it quantifies the influence of a journal on secondary publications. It does not however evaluate the practical usefulness of primary documents. Usefulness is field-related and varies greatly among specialities. We introduce a new bibliographic criterion, the "reading factor", and define it as the ratio between the number of electronic consultations of a particular journal (i.e., number of clicks on a hyper-link) and the mean number of electronic consultations of all the journals studied (itself calculated by dividing the total number of electronic accesses by the number of journals in the database). We describe its observed distribution, relative to that of the impact factor, based on electronic consultation records from our University Hospital medical digital library, where full-text electronic versions of 45 major biomedical journals have been available since December 1997. From this analysis we found no correlation between the 1999 reading factor and the 1998 impact factor of these 45 journals, and we observed a dramatic change in the hierarchy of journals upon using the reading factor as the yardstick rather than the impact factor. Moreover, we describe how using the reading factor has helped in managing the collection of our University Hospital's virtual library. The selection of journals to be discarded from the virtual library for the year 2001 was based on journals' RF values and this process will repeated over the coming years. The reading factor also permits a cost-analysis of a virtual library. CONCLUSION: The measurement of the reading factor is highly automated, practical and efficient. It appears as a new tool for electronic collection management by librarians, well fitting with economical data.

Cost effectiveness of a medical digital library.

The rapid increase in the price of electronic journals has made the optimization of collection management an urgent task. As there is currently no standard procedure for the evaluation of this problem, we applied the Reading Factor (RF), an electronically computed indicator used for consultation of individual articles. The aim of our study was to assess the cost effective impact of modifications in our digital library (i.e. change of access from the Intranet to the Internet or change in editorial policy). The digital OVID library at Rouen University Hospital continues to be cost-effective in comparison with the interlibrary loan costs. Moreover, when electronic versions are offered alongside a limited amount of interlibrary loans, a reduction in library costs was observed.

How to select publications on occupational health: the usefulness of Medline and the impact factor.

OBJECTIVES: Publications in the field of occupational health appear in various journals, including those of other medical specialties. This complicates the follow up of literature for specialists in this field. On the basis of Medline and the impact factor, this diversity was assessed, and a cost effective method for selecting the most pertinent journals in the practice of occupational health was proposed. METHODS: A Medline search identified all the articles published in 1998 with occupational diseases or occupational exposures as the main topic. These articles were classified based on the journals in which they appeared. The journals were then compared according to their subject area, the number of articles that were published in the fields studied, and their impact factor. RESULTS: The search retrieved 2247 articles, published in 577 different journals in 1998. Each journal published between one and 105 articles during this period (mean 3.89). However, only 1.4% of the journals accounted for more than 25% of the total articles published. More than half of the articles were published in journals dealing with general practice or medical specialties other than occupational health. Only 66% of retrieved journals had an impact factor, and more than 80% of the articles were published in journals with an impact factor <2. CONCLUSION: Simply following up occupational health journals is not sufficient to meet the requirements of the occupational health professional. Moreover, the use of the impact factor cannot be considered as a reliable research tool to assess follow up. Two lists of eight and 38 journals were thus set up. They permit a literature coverage of 27% and 52% respectively in the specific fields studied, and this seems to be the optimal compromise between time and literature covered. Lastly, practical procedures are suggested to follow up literature and obtain abstracts from selected journals on the internet.

A study comparing centralized CD-ROM and decentralized intranet access to MEDLINE.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of a decentralized intranet access in each medical department as opposed to centralized unique MEDLINE access in the medical library. DESIGN: A two-phase questionnaire to evaluate MEDLINE use was given to junior and senior physicians at Rouen University Hospital (RUH). Phase I (August-October 1996) corresponded to a time period when centralized access was the only means of access available and phase II (August-October 1997) to a time period following the introduction of decentralized intranet access. RESULTS: A total of 168 physicians filled out at least one phase of the questionnaire, among whom 123 (73%) filled out both phases. Use of MEDLINE significantly increased in 1997 (average of 10.2+/-1.1 searches in three months) versus 1996 (average of 4.9+/-0.7 searches in three months, P<0.0001). The aim of searches changed, becoming significantly more care oriented in phase II (P<0.0001). The number of searches performed by the physicians alone increased (P<0.0001) and searches performed by the librarian decreased (P<0.0001) in phase II. The method of searches also changed, as searches by author (P< 0.0001), by journal (P = 0.0042), and by free word (P = 0.0027) increased in phase II. Knowledge of the following concepts of MEDLINE significantly increased: explosion (P<0.0001), scope note (P<0.0001), Abridged Index Medicus (AIM) journals (P<0.0001), Medical Subject Headings (MeSH) qualifier (P<0.0001), and focus (P<0.0001). CONCLUSION: A decentralized intranet access to MEDLINE increased the number of searches and knowledge of this bibliographic database. MEDLINE intranet access modified the purpose and the methods of searching.

CISMeF: a structured health resource guide.

In 1999, the Internet has become a major source of health information. The objective of CISMeF is to catalogue and index the main French-speaking health resources. In September 1999, the number of indexed resources totaled over 7,100 with a mean of 75 new sites per week. CISMeF uses two standard tools for organizing information: the Medline bibliographic database MeSH thesaurus and the Dublin Core metadata format. Resources included in CISMeF are described by the following: title, author or creator, subject and keywords, description, publisher, date, resource type, format, identifier, and language. To index resources, CISMeF uses five levels of hierarchy: "meta-term", category, keyword, subheading, and resource type. CISMeF contains a thematic index, including medical specialities and an alphabetic index. CISMeF respects the Net Scoring, criteria to assess the quality of health information on the Internet. The CISMeF project offers a valuable tool for the French-speaking health community: 2,500 computer users visit the Web site each working day.