The Role of Computational Fluid Dynamics in the Management of Unruptured Intracranial Aneurysms: A Clinicians' View

Objective. The importance of hemodynamics in the etiopathogenesis of intracranial aneurysms (IAs) is widely accepted. Computational fluid dynamics (CFD) is being used increasingly for hemodynamic predictions. However, alogn with the continuing development and validation of these tools, it is imperative to collect the opinion of the clinicians. Methods. A workshop on CFD was conducted during the European Society of Minimally Invasive Neurological Therapy (ESMINT) Teaching Course, Lisbon, Portugal. 36 delegates, mostly clinicians, performed supervised CFD analysis for an IA, using the @neuFuse software developed within the European project @neurIST. Feedback on the workshop was collected and analyzed. The performance was assessed on a scale of 1 to 4 and, compared with experts' performance. Results. Current dilemmas in the management of unruptured IAs remained the most important motivating factor to attend the workshop and majority of participants showed interest in participating in a multicentric trial. The participants achieved an average score of 2.52 (range 0–4) which was 63% (range 0–100%) of an expert user. Conclusions. Although participants showed a manifest interest in CFD, there was a clear lack of awareness concerning the role of hemodynamics in the etiopathogenesis of IAs and the use of CFD in this context. More efforts therefore are required to enhance understanding of the clinicians in the subject

Biomaterials for Injectable Therapeutic Implants

Injectable biomaterials that have the ability to form semi-solid implants in situ are of keen interest for therapeutic applications. The materials may be used to fill in pathological vascular spaces or be designed to possess functional properties such as being radiopaque for an improved visibility during image-guided minimally invasive interventions, or induce a localized biological activity. Among the variety of solidification principles that may be used to produce implants in situ, the precipitation of water-insoluble polymers driven by solubility changes shows some particular features that may be valuable for specific therapeutic applications. This paper reviews some of the applications of these implant-forming biomaterials in interventional radiology, urology, and oncology

Change in aneurysmal flow pulsatility after flow diverter treatment

Motivation: Treatment of intracranial aneurysms with flow diverters (FDs) has recently become an attractive alternative. Although considerable effort has been devoted to understand their effects on the time-averaged or peak systolic flow field, no previous study has analyzed the variability of FD-induced flow reduction along the cardiac cycle. Methods: Fourteen saccular aneurysms, candidates for FD treatment because of their morphology, located on the internal carotid artery were virtually treated with FDs and pre- and post-treatment blood flow was simulated with CFD techniques. Common hemodynamic variables were recorded at each time step of the cardiac cycle and differences between the untreated and treated models were assessed. Results: Flow pulsatility, expressed by the pulsatility index (PI) of the velocity, significantly increased (36.0%; range: 14.6–88.3%) after FD treatment. Peak systole velocity reduction was significantly smaller (30.5%; range: 19.6–51.0%) than time-averaged velocity reduction (43.0%; range: 29.1–69.8%). No changes were observed in the aneurysmal pressure. Conclusions: FD-induced flow reduction varies considerably during the cardiac cycle. FD treatment significantly increased the flow pulsatility in the aneurysm.Fil: Larrabide, Ignacio. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Grupo de Plasmas Densos Magnetizados. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Grupo de Plasmas Densos Magnetizados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Geers, Arjan J.. Universitat Pompeu Fabra; EspañaFil: Morales; Hernán G.. Medisys; FranciaFil: Bijlenga, Philippe. Universidad de Ginebra; SuizaFil: Rufenacht, Daniel A.. Hirslanden Clinic; Suiz

Effect of aneurysm and ICA morphology on hemodynamics before and after flow diverter treatment

Background: Flow diverter (FD) treatment aims to slow down blood flow inside the aneurysm and increase the average time that blood resides in the aneurysm. Objective: To investigate the relationship between vessel and aneurysm morphology and their influence on the way in which braided FDs change intra-aneurysmal hemodynamics. Materials and methods: Twenty-three patient-specific intracranial aneurysm models at the supraclinoid segment of the internal carotid artery were studied. Vessel and aneurysm morphology was quantified and blood flow was modeled with computational fluid dynamics simulations. The relation between morphologic variables and the hemodynamic variables, WSS (wall shear stress) and totime (ratio between the aneurysm volume and inflow at the aneurysm neck), was assessed statistically. Results: Intra-aneurysmal flow was less dependent on the vessel than on aneurysm morphology. In summary, after treatment with a FD, a greater aneurysm flow reduction and redirection to the vessel main stream should be expected for (a) aneurysms located further away from the curvature peak, (b) aneurysms on the inner side of the bend, (c) aneurysms with no proximal stenosis, and (d) larger aneurysms.Fil: Larrabide, Ignacio. Universitat Pompeu Fabra; España. Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine; España. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Grupo de Plasmas Densos Magnetizados. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Grupo de Plasmas Densos Magnetizados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Geers, Arjan J.. Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine; España. Universitat Pompeu Fabra; EspañaFil: Morales, Hernán G.. Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine; España. Universitat Pompeu Fabra; EspañaFil: Aguilar, Martha L.. Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine; España. Universitat Pompeu Fabra; EspañaFil: Rufenacht, Daniel A.. Hirslanden Clinic; Suiz

Second-generation three-dimensional reconstruction for rotational three- dimensional angiography

Rationale and Objectives. The purpose of this study was to assess the feasibility and accuracy of three-dimensional (3D) reconstruction techniques for digital subtraction angiography (DSA) in planning and evaluation of minimally invasive image-controlled therapy. Materials and Methods. Using a standard, commercially available system, the authors acquired DSA images and corrected them for inherent distortions. They designed and implemented parallel and multiresolution versions of cone-beam reconstruction techniques to reconstruct high-resolution targeted volumes in a short period of time. Testing was performed on anatomically correct, calibrated in vitro models of a cerebral aneurysm. These models were used with a pulsatile circulation circuit to allow for blood flow simulation during DSA, computed tomographic (CT) angiography, and magnetic resonance (MR) angiography image acquisitions. Results. The multiresolution DSA-based reconstruction protocol and its implementation allowed the authors to achieve reconstruction times and levels of accuracy for the volume measurement of the aneurysmal cavities that were considered compatible with actual clinical practice. Comparison with data obtained from other imaging modalities shows that, besides vascular tree depiction, the DSA-based true 3D technique provides volume estimates at least as good as those obtained from CT and MR angiography. Conclusion. The authors demonstrated the feasibility and potential of true 3D reconstruction for angiographic imaging with DSA. On the basis of the model testing, this work addresses both the timing and quantification required to support minimally invasive image-controlled therapy

The role of computational fluid dynamics in the management of unruptured intracranial aneurysms: a clinicians' view

Objective: The importance of hemodynamics in the etiopathogenesis of intracranial aneurysms (IAs) is widely accepted./nComputational fluid dynamics (CFD) is being used increasingly for hemodynamic predictions. However, alogn with the/ncontinuing development and validation of these tools, it is imperative to collect the opinion of the clinicians. Methods: A workshop/non CFD was conducted during the European Society of Minimally Invasive Neurological Therapy (ESMINT) Teaching Course,/nLisbon, Portugal. 36 delegates, mostly clinicians, performed supervised CFD analysis for an IA, using the @neuFuse software/ndeveloped within the European project @neurIST. Feedback on the workshop was collected and analyzed. The performance/nwas assessed on a scale of 1 to 4 and, compared with experts’ performance. Results: Current dilemmas in the management of/nunruptured IAs remained the most important motivating factor to attend the workshop and majority of participants showed/ninterest in participating in a multicentric trial. The participants achieved an average score of 2.52 (range 0–4) which was 63% (range 0–100%) of an expert user. Conclusions: Although participants showed a manifest interest in CFD, there was a clear lack of/nawareness concerning the role of hemodynamics in the etiopathogenesis of IAs and the use of CFD in this context. More efforts/ntherefore are required to enhance understanding of the clinicians in the subject.The authors would like to thank the European Commission,/nVI Framework Program, Priority 2, Information Society/nComputational Intelligence and Neuroscience 11/nTechnologies, a European Public Funded Organization,/nfor funding @neurIST Project (2) (www.aneurist.org) and/nallowing this study (Research Grant no. IST-FP6-027703). The funding was provided in the form of financial support/nto first two authors along with the arrangement of necessary/nresources to conduct the workshop