Needle biopsy is a routine medical procedure for examining tissue or biofluids for the presence of disease using standard methods of pathology. The finite element analysis (FEA) methodology can provide guidance for optimizing the geometric parameters. The needle biopsy is simulated and analyzed while varying the needle angle, the aperture size and the slice-push ratio k. The results indicate that tissue reaction force in the axial direction of needle gradually decreases, and the stress and strain are more concentrated at the tip of needle with the increases of tip angle; the tissue reaction force decreases, and the torque increases while the slice-push ratio increases; and higher slice–push ratio can increase the peak stress concentration on the cutting edge and deformation of tissue; in the process of core needle cutting, increasing slice–push ratio can reduce the tissue reaction force significantly. While the aperture on distal wall of outer cannula becomes wider, the tissue reaction force increases significantly, and the cutting process will be more unstable. The results have the potential to provide important insight for improving the needle biopsy design process.
Endovascular aneurysm repair (EVAR) techniques have been widely used for the treatment of abdominal aortic aneurysm (AAA). EVAR is associated with lower postoperative morbidity and mortality than traditional surgical procedure to treat AAA [1]. However, during the patient’s follow-up, postoperative complications may occur and secondary interventions are required [2]. Stent-grafts fixation in the vessel affects the success of endovascular aneurysm repair. Researches indicate that insufficient stent-graft radial force is attributed to post-surgery complications, such as prosthesis migration and endoleak type I [3, 4]. Endoleak type I happens when there is not a complete contact between stent graft rings and vessel wall. A great radial force can prevent full obturation in the landing zone. The distal endograft fixation also has a great influence on proximal endograft migration after EVAR [5]. Therefore the radial force of the stent plays a significant role. Single stent-graft ring comprise a series of expandable Z-shaped structural elements (known as “struts”). Currently, there are series of Z-shaped stent-grafts on the market and the struts number ranges from 5 to 12. This work intends to analyze the influence of stent-graft struts number on the radial force. Finite-element analysis (FEA) and experimental method are used.
Percutaneous mechanical thrombectomy (PMT) is an efficient way to treat the deep vein thrombosis (DVT). During the course of treatment, blood cell will be destroyed by the component of thrombectomy device, causing hemolysis. In this research, the computational fluid dynamics (CFD) methodology is used to investigate hemolysis effect of rotary cutting thrombectomy device. And a prototype of rotary cutting thrombectomy device is made to carry out two corresponding experiments to verify the simulation results. CFD results indicate that the hemolysis rate increases significantly with the rise of rotation speed of cutting component. The experimental results are in good consistence with the CFD results, and shows that the longer the working time, the higher the hemolysis rate. Thus a rotation speed between 5,000 rpm and 10,000 rpm can be considered reasonable. The results can be served as a helpful guidance for the design of such thrombectomy devices.
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