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Vanzin J.R.,Interventional Neuroradiology of the Neurology and Neurosurgery Service | Abud D.G.,University of Sao Paulo | Rezende M.T.S.,Federal University of Minas Gerais | Moret J.,Interventional Neuroradiology
Arquivos de Neuro-Psiquiatria

Objective: The Brazilian public health system determines a quantity of coils allowed to treat a cerebral aneurysm. The goal of this paper was to determine the number of coils necessary to treat an aneurysm based on size. Methods: All patients harboring an aneurysm treated by endovascular approach between 1999 and 2003 were reviewed. Results: There were 952 aneurysms included. Mean diameter sac was 8.2 mm with 7.9 coils per aneurysm. Out of 462 small aneurysms, mean size was 4.8 mm, with 4.6 coils/aneurysm used. A total of 315 medium aneurysms were treated, mean size was 8.6 mm, with 8.2 coils. Out of 135 large, mean size was 17 mm, with 16.1 coils. Forty giant aneurysms were treated with a mean size of 32 mm and 28.7 coils. Conclusions: We propose size as a reference to predict the number of coils necessary to treat each aneurysm: one coil for each millimeter of diameter. Source

Cebral J.R.,George Mason University | Sheridan M.,Institute for Research and Education | Putman C.M.,Interventional Neuroradiology | Putman C.M.,George Washington University
American Journal of Neuroradiology

BACKGROUND AND PURPOSE: Intracranial aneurysms with irregular shapes and blebs or secondary outpouchings have been correlated with increased rupture risk. The purpose of this study was to investigate possible associations between the local hemodynamics and the formation of blebs in cerebral aneurysms. MATERIALS AND METHODS: Computational models of 20 cerebral aneurysms harboring 30 welldefined blebs were constructed from 3D rotational angiographies. Models representing the aneurysm before bleb formation were constructed by virtually removing the blebs from the anatomic models. Computational fluid dynamics simulations of the aneurysm before and after bleb formation were performed under pulsatile flows. Flow and WSS visualizations were used to analyze the local hemodynamics in the region of the aneurysm that developed the bleb. RESULTS: Most blebs (80%) occurred at or adjacent to the aneurysm region with the highest WSS before bleb formation, and near the flow impaction zone. Most blebs (83%) were found in regions of the aneurysm previously subjected to high or moderate WSS and progressed to low WSS states after the blebs were formed. Most blebs (77%) were aligned or adjacent to the inflow jet, whereas 17% were aligned with the outflow jet, and only 6% were not aligned with the flow direction. In addition, 90% of the aneurysms had maximal WSS higher than or similar to the WSS in the parent artery. CONCLUSIONS: Blebs form at or adjacent to regions of high WSS and are aligned with major intraaneurysmal flow structures. Formation of blebs results in a lower WSS state with formation of a counter current vortex. These findings imply that locally elevated WSS could contribute to the focalized wall damage that formed these structures. Source

Peschillo S.,University of Rome La Sapienza | Missori P.,University of Rome La Sapienza | Piano M.,Interventional Neuroradiology | Cannizzaro D.,University of Rome La Sapienza | And 3 more authors.
Neurosurgical Review

Blood blister-like aneurysms (BBA) were described for the first time in the 1990s, as small hemispherical bulges arising from a very fragile arterial wall. Until 2008, it was thought that this type of aneurysm almost exclusively affected the internal carotid artery, in particular, its dorsal portion. Subsequently, it was discovered that a BBA may also be present on the anterior communicating artery and on the vessels of the posterior cranial fossa. However, we found no reports in English-language literature of BBA arising from the middle cerebral artery (MCA). In this article, we present three cases of MCA BBA and discuss the unique diagnostic and therapeutic aspects of this vascular lesion. In our retrospective, multicenter review of 1330 patients with non-traumatic subarachnoid hemorrhage admitted to our services from 2000 to 2013, we found three cases (all in men) of MCA BBA. The patients’ outcome was assessed using the modified Rankin scale. All three patients underwent angio-computed tomography, which did not reveal any aneurysms. Digital subtraction angiography performed within 24–48 h after admission, in all cases, demonstrated a very small aneurysm (<2 mm), with a triangular shape and abroad base, at non-branching sites of MCA. All the aneurysms were treated: one by wrapping + clipping, one by wrapping + flow-diverter stent, and one with coils. At the time of surgery, the aneurysms appeared on the surface of the parent artery without any involvement of the branches. All presented as blister-like aneurysms that were thin-walled and lacked a surgical neck. At the time of discharge, the outcome was good in one patient and poor in the other two. Our cases demonstrate that BBA can also arise from the MCA, despite the lack of previous reports of this occurrence; a BBA should be suspected, particularly in cases of non-perimesencephalic subarachnoid hemorrhage in which the presence of a MCA aneurysm is suspected but not revealed by digital subtraction angiography or angio-computed tomography. © 2014, Springer-Verlag Berlin Heidelberg. Source

Sforza D.M.,George Mason University | Lohner R.,George Mason University | Putman C.,Interventional Neuroradiology | Cebral J.R.,George Mason University
International Journal for Numerical Methods in Biomedical Engineering

The effects of parent artery motion on the hemodynamics of basilar tip saccular aneurysms and its potential effect on aneurysm rupture were studied. The aneurysm and parent artery motions in two patients were determined from cine loops of dynamic angiographies. The oscillatory motion amplitude was quantified by registering the frames. Patient-specific computational fluid dynamics (CFD) models of both aneurysms were constructed from 3D rotational angiography images. Two CFD calculations were performed for each patient, corresponding to static and moving models. The motion estimated from the dynamic images was used to move the surface grid points in the moving model. Visualizations from the simulations were compared for wall shear stress (WSS),velocity profiles, and streamlines.I both patients, a rigid oscillation of the aneurysm and basilar artery in the anterio-posterior direction was observed and measured. The distribution of WSS was nearly identical between the models of each patient, as well as major intra-aneurysmal flow structures, inflow jets, and regions of impingement. The motion observed in pulsating intracranial vasculature does not have a major impact on intraaneurysmalhemodynamic variables. Parent artery motion is unlikely to be a risk factor for increased risk of aneurysmal rupture. © 2010 John Wiley& Sons, Ltd. Source

Castro M.A.,CONICET | Olivares M.C.A.,Favaloro University | Putman C.M.,Interventional Neuroradiology | Cebral J.R.,George Mason University
Medical and Biological Engineering and Computing

The aim of this work was to determine whether or not Newtonian rheology assumption in image-based patient-specific computational fluid dynamics (CFD) cerebrovascular models harboring cerebral aneurysms may affect the hemodynamics characteristics, which have been previously associated with aneurysm progression and rupture. Ten patients with cerebral aneurysms with lobulations were considered. CFD models were reconstructed from 3DRA and 4DCTA images by means of region growing, deformable models, and an advancing front technique. Patient-specific FEM blood flow simulations were performed under Newtonian and Casson rheological models. Wall shear stress (WSS) maps were created and distributions were compared at the end diastole. Regions of lower WSS (lobulation) and higher WSS (neck) were identified. WSS changes in time were analyzed. Maximum, minimum and time-averaged values were calculated and statistically compared. WSS characterization remained unchanged. At high WSS regions, Casson rheology systematically produced higher WSS minimum, maximum and time-averaged values. However, those differences were not statistically significant. At low WSS regions, when averaging over all cases, the Casson model produced higher stresses, although in some cases the Newtonian model did. However, those differences were not significant either. There is no evidence that Newtonian model overestimates WSS. Differences are not statistically significant. © 2014, International Federation for Medical and Biological Engineering. Source

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