NON-NEWTONIAN COMPUTATIONAL HEMODYNAMICS IN TWO PATIENT-SPECIFIC CEREBRAL ANEURYSMS WITH DAUGHTER SACCULES

Hemodynamic factors play important roles in the formation, progression and rupture of cerebral aneurysms, and the Wall Shear Stress （WSS） and Oscillatory Shear Index （OSI） on the aneurysms are considered to be correlated with their growth and rupture. In this article, two computational models based on patient-specific cerebral aneurysms with daughter saccule are constructed from 3D-RA image data, one is lateral aneurysm located in middle cerebral artery （CA1） and the other is terminal aneurysm located in anterior communicating artery （CA2）, The corresponding models of the two aneurysms by removing daughter saccule are established in order to investigate the initiation and growth of the daughter saccule. The flow patterns and the distributions of hemodynamic factors in the two aneurysms before and after daughter saccule is removed are obtained by solving the governing equations with the commercial CFD software Ansys CFX11.0 under the non-Newtonian fluid assumption. By analyzing the flow patterns, it is concluded that the aneurysms with daughter saccules have more complex and unstable flow patterns and hence are prone to rupture. By comparing the distribution of OSI, a hypothesis that a high OSI causes the growth of the daughter saccule is presented.

Influence of Strut Cross-section of Stents on Local Hemodynamics in Stented Arteries

Stenting is a very effective treatment for stenotic vascular diseases, but vascular geometries altered by stent implantation may lead to flow disturbances which play an important role in the initiation and progression of restenosis, especially in the near wall in stented arterial regions. So stent designs have become one of the indispensable factors needed to be considered for reducing the flow disturbances. In this paper, the structural designs of strut cross-section are considered as an aspect of stent designs to be studied in details. Six virtual stents with different strut cross-section are designed for deployments in the same ideal arterial model. Computational fluid dynamics（CFD） methods are performed to study how the shape and the aspect ratio（AR） of strut cross-section modified the local hemodynamics in the stented segments. The results indicate that stents with different strut cross-sections have different influence on the hemodynamics. Stents with streamlined cross-sectional struts for circular arc or elliptical arc can significantly enhance wall shear stress（WSS） in the stented segments, and reduce the flow disturbances around stent struts. The performances of stents with streamlined cross-sectional struts are better than that of stents with non-streamlined cross-sectional struts for rectangle. The results also show that stents with a larger AR cross-section are more conductive to improve the blood flow. The present study provides an understanding of the flow physics in the vicinity of stent struts and indicates that the shape and AR of strut cross-section ought to be considered as important factors to minimize flow disturbance in stent designs.

Machine learning of synaptic structure with neurons to promote tumor growth

In this paper,we use machine learning techniques to form a cancer cell model that displays the growth and promotion of synaptic and electrical signals.Here,such a technique can be applied directly to the spiking neural network of cancer cell synapses.The results show that machine learning techniques for the spiked network of cancer cell synapses have the powerful function of neuron models and potential supervisors for different implementations.The changes in the neural activity of tumor microenvironment caused by synaptic and electrical signals are described.It can be used to cancer cells and tumor training processes of neural networks to reproduce complex spatiotemporal dynamics and to mechanize the association of excitatory synaptic structures which are between tumors and neurons in the brain with complex human health behaviors.

Proximal true lumen collapse in a chronic type B aortic dissection patient:A case report

BACKGROUND In the context of aortic dissection,increasing pressure within the newly formed false lumen can result in the progressive compression of the true aortic channel.However,true lumen collapse in chronic type B aortic dissection(cTBAD)patients is rare,with few clinical or experimental studies to date having explored the causes of such collapse.CASE SUMMARY In the present report,we describe a rare case of true-lumen collapse in an 83-yearold patient diagnosed with cTBAD,and we discuss potential therapeutic interventions for such cases.Following thoracic endovascular aortic repair(TEVAR),computed tomography angiography revealed satisfactory stent-graft positioning,no endoleakage,true lumen enlargement,thrombus formation in the false lumen,and slight enlargement of the true lumen distal to the stent-graft.Computational hemodynamic analyses indicated that the wall shear stress and pressure within the false lumen were significantly reduced following TEVAR.CONCLUSION TEVAR treatment of cTBAD patients suffering from proximal true lumen collapse can facilitate some degree of effective remodeling.