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Rayz V.L.,University of California at San Francisco | Boussel L.,CREATIS LRMN | Ge L.,University of California at San Francisco | Leach J.R.,University of California at San Francisco | And 4 more authors.
Annals of Biomedical Engineering | Year: 2010

Thrombus formation in intracranial aneurysms, while sometimes stabilizing lesion growth, can present additional risk of thrombo-embolism. The role of hemodynamics in the progression of aneurysmal disease can be elucidated by patient-specific computational modeling. In our previous work, patient-specific computational fluid dynamics (CFD) models were constructed from MRI data for three patients who had fusiform basilar aneurysms that were thrombus-free and then proceeded to develop intraluminal thrombus. In this study, we investigated the effect of increased flow residence time (RT) by modeling passive scalar advection in the same aneurysmal geometries. Non-Newtonian pulsatile flow simulations were carried out in base-line geometries and a new postprocessing technique, referred to as "virtual ink" and based on the passive scalar distribution maps, was used to visualize the flow and estimate the flow RT. The virtual ink technique clearly depicted regions of flow separation. The flow RT at different locations adjacent to aneurysmal walls was calculated as the time the virtual ink scalar remained above a threshold value. The RT values obtained in different areas were then correlated with the location of intra-aneurysmal thrombus observed at a follow-up MR study. For each patient, the wall shear stress (WSS) distribution was also obtained from CFD simulations and correlated with thrombus location. The correlation analysis determined a significant relationship between regions where CFD predicted either an increased RT or low WSS and the regions where thrombus deposition was observed to occur in vivo. A model including both low WSS and increased RT predicted thrombus-prone regions significantly better than the models with RT or WSS alone. © 2010 The Author(s).

Krefting D.,Charite - Medical University of Berlin | Glatard T.,CREATIS LRMN | Korkhov V.,University of Amsterdam | Montagnat J.,French National Center for Scientific Research | Silvia O.,University of Amsterdam
CEUR Workshop Proceedings | Year: 2011

Motivation: In the last years various distributed computing infrastructures (DCIs) have been developed to support national and international research activities. Today several applications from diverse domains have been ported to them. For example, workflowbased grid applications for medical imaging have been developed in the Netherlands within the VL-e project, in France within the EGI biomed VO and in Germany within the German medical D-Grid projects. These applications are based on the resources and workflow systems provided by respective grid infrastructures, and researchers now face difficulties to exchange applications and data across the DCIs. This would be important to obtain access to additional resources and to enable sharing of applications and methodology. Unfortunately today the mobility across DCIs at application level is hardly supported. Results: The European project SHIWA - Sharing Interoperable Workflows for large-scale scientific simulations on Available DCIs1 aims to realize interoperability at workflow level. This will allow domain researchers to share and reuse their scientific workflows across DCIs. Different use cases are identified which result in a two-fold approach: coarse-grained and fine-grained workflow interoperability. First results are presented for two pilot applications - neuroimaging and chemistry - And two workflow systems - MOTEUR and GWES. We analyze the similarities and differences between these systems, and show implementation strategies for easily combine and translate scientific workflows. These results enable sharing and reusing workflows and grid services between EGI, D-Grid, and Dutch Grid infrastructures Availability: The workflow managers GWES and MOTEUR are both open source and free for academic use. The mentioned workflows will be published within the SHIWA platform.

Cooper J.,University of Oxford | Cervenansky F.,CREATIS LRMN | De Fabritiis G.,Barcelona Biomedical Research Park | Fenner J.,University of Sheffield | And 10 more authors.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2010

The Virtual Physiological Human (VPH) is a major European e-Science initiative intended to support the development of patient-specific computer models and their application in personalized and predictive healthcare. The VPH Network of Excellence (VPH-NoE) project is tasked with facilitating interaction between the various VPH projects and addressing issues of common concern. A key deliverable is the 'VPH TOOLKIT'-a collection of tools, methodologies and services to support and enable VPH research, integrating and extending existing work across Europe towards greater interoperability and sustainability. Owing to the diverse nature of the field, a single monolithic 'toolkit' is incapable of addressing the needs of the VPH. Rather, the VPH TOOLKIT should be considered more as a 'toolbox' of relevant technologies, interacting around a common set of standards. The latter apply to the information used by tools, including any data and the VPH models themselves, and also to the naming and categorizing of entities and concepts involved. Furthermore, the technologies and methodologies available need to be widely disseminated, and relevant tools and services easily found by researchers. The VPH-NoE has thus created an online resource for the VPH community to meet this need. It consists of a database of tools, methods and services for VPH research, with a Web front-end. This has facilities for searching the database, for adding or updating entries, and for providing user feedback on entries. Anyone is welcome to contribute. This journal is © 2010 The Royal Society.

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