研究两类药物释放曲线对血管壁中药物浓度分布的影响,为药物洗脱支架(DES)的优化设计提供依据;建立三维支架—血管模型,采用数值方法分析了雷帕霉素和紫杉醇两种药物释放曲线下血管壁中药物的浓度分布;初始药物释放率的增大会导致初始血管壁内药物浓度的增大,但随着时间的增加,血管壁中的药物浓度均趋于平稳。两种药物释放曲线下血管壁中的药物浓度均是随着时间的变化先增加后减少的,相比来说,雷帕霉素血管壁中的药物浓度随着时间变化的趋势要比紫杉醇血管壁中的药物浓度随着时间变化的趋势平稳,并且雷帕霉素血管壁中的药物浓度分布要比紫杉醇中血管壁中的药物浓度分布均匀。血管壁中药物浓度变化趋势的平稳性以及药物浓度分布的均匀性表明,雷帕霉素药物释放曲线要优于紫杉醇药物释放曲线。

To study the effects of two drug release profiles on the drug concentration for better design of drug -eluting stents (DES).A 3D virtual drug -eluting -vessel stent was modeled,and numerical simulation was used to investigate the drug concentration within the vessel wall at the drug release profile of rapamycin and paclitaxel,The initial drug concentration was increased with initial drug release rate increasing,but over time the drug concentration in the vessel wall would be stabilized.The drug concentrations pro-duced by both drug release profiles were first increased and then decreased with time,and compared with the concentration variation trend of paclitaxel,the concentration variation trend of rapamycin was steadier.In addition,the rapamycin concentration distribution in the vessel wall was more uniform than the paclitaxel concentration distribution.The stability of the drug concentration variation trend and the uniformity of drug concentration within the vessel wall show that rap

血管内超声图像的血管壁内外膜边缘检测是IVUS图像处理中必不可少的步骤与重要环节，基于主动轮廓模型的血管壁边缘提取的效果好坏很大程度上依赖于初始轮廓能否较为精确的选取。提出了一种提取血管壁边缘的新方法，以自适应阈值分割的方式降低目标图像的复杂度，结合 marr 边缘检测算子找到血管壁内外膜边缘的初始轮廓，在此基础之上，采用改进的GVF-snake算法使初始轮廓线精确收敛于真实的血管壁边缘，实验结果验证了此方法的有效性。

The intima and adventitia edge detection of vascular wall is a key step in Intravascular Ultrasound(IVUS) processing. An accurate selection of initial contour would be significant for edge extraction based on active contour model. This paper puts forward a new method for extracting the edge of vascular wall. At first, adaptive threshold segmentation is used to reduce the complexity of the IVUS original images,then find the initial contour line of the vascular wall with Marr edge detection. Finally, an improved GVF-snake model is used to make the initial contour line converge to the true edge of vascular wall accurately. The experimental results confirm the validity of the new method.

血流特效场景可以增强虚拟手术的真实感。虚拟手术中的血流特效场景包括了有交互的血液模拟及血管壁模拟。首先基于光滑粒子流体动力学,使用Physx物理引擎模拟血液流动的物理形态,并利用Screen Space Flow算法对血流表面进行实时渲染。然后基于质点-弹簧模型,提出使用Physx物理引擎模拟可交互、有弹性形变及可切割的血管壁。最后实现两个实验场景:场景一实现肺动脉内大规模血液流动的特效;场景二实现在用户交互下的血管壁形变和切割,并通过触发事件实现血管壁破裂流血的特效。实验结果表明,该血流及血管壁模拟方法在40 000个粒子下仍能保证实时绘制,满足虚拟手术的需求。

Blood flood effects scene can enhance the sense of reality in virtual surgery.The blood flow effects scene in virtual surgery includes both interactive blood simulation and vessel wall simulation.First of all on the basis of SPH,it utilizes Physx to simulate blood flood physical form and by using Screen Space Flow algorithm it carries out real-time rendering with blood surface.Then based on Mass-Spring model it suggests using Physx to simulate interactive,stretchy and rupturable vessel wall.Finally it implements two experimental scenes:scene one implements the effects of large scale blood flow in pulmonary artery;scene two implements vessel wall deformation and segmentation under user interaction and implements by triggering events vessel wall wounding and blooding effects.Experiment results show that the blood flow and vessel wall simulation method can still ensure real-time rendering with 40 000 particles so that it meets the requirement of virtual surgery.

目的总结胃肠道管壁弥漫血管瘤的CT表现,增强对本病影像表现的认识。方法回顾性分析2012年4-11月于我院就诊的4例胃肠道管壁弥漫血管瘤患者的临床资料及影像表现。3例行常规腹部平扫+增强CT扫描,1例因下消化道出血行盆腔平扫+增强CT扫描。结果 4例患者,男性3例,年龄分别为16、30、42岁;女性1例,年龄33岁。3例自出生后反复无痛性血便,1例血便1月余。CT显示病变累及胃壁和多节段肠壁,表现为较长节段管壁环形不规则增厚,局部合并管腔狭窄;病变内均可见多个点状或结节状钙化影。增强扫描常规动脉期、门静脉期病变无明显强化,延迟90~120 s,病变渐进性强化,CT值升高20~30 HU。1例在延迟50 min后扫描,病变呈中度均匀强化,CT值约60 HU。病变邻近动脉血管均未见异常。3例引流至门静脉,1例经腹部皮下迂曲静脉引流,其中2例引流静脉粗大。2例门脉正常结构消失,显示门静脉海绵样变。结论对自幼血便或长期反复血便者,应注意胃肠道管壁弥漫血管瘤的可能,CT表现具有特征性,结合临床病史可做出正确诊断。

Objective To improve the understanding of gastrointestinal wall diffuse hemangioma (GWDH)by summarizing its CT features. Methods Clinical data and imaging features of 4 GWDH patients admitted to our hospital from April to November 2012 were retrospectively analyzed. Of the 4 patients, 3 underwent routine abdominal plain and enhanced CT scanning, 1 underwent pelvis plain and enhanced CT scanning due to bleeding in the lower digestive tract. Results The average age of the 4 patient was 16,30,42 and 33 years old, respectively. The 3 male patients had presented with repeated painless bloody stools since their childhood and the female patient had bloody stools for more than 1 month. CT showed that the lesions involving gastric wall and several segments of intestinal wall were manifested as circularly and irregularly thickened long segment wall with local lumen stricture and multiple punctuate and nodular calcification shadows. Enhanced CT showed no significant change in the lesions at conve

分析血管壁的弹性形变,对心血管疾病的临床诊治和手术方案选择有重要意义.在进行合理假设的前提下,首先建立微元线段的小应变分析模型,再利用有限元分析方法将血管壁区域划分为若干三角形面微元,用三角形的三个顶点和三条边的位移函数导出三角形微元域的形变模型,通过模型计算结果分析及有效性验证表明:血管壁小应变力学模型具有较好的适用性和实用性.与文献方法相比,最后呈现的结果不仅能计算出应变大小,还能显示应变方向,而且分别给出三个方向的应变值.

It has a great significance to analyze the elastic deformation of the vessel wall for cardiovascular diseases’ clinical treatment and the selection of the surgical plan .On the premise of making reasonable assumptions ,firstly ,establish the deformation model of infinitesimal’s displacement .Secondly ,use the finite element analysis method to divide the area of the vessel wall into a number of triangular surface infinitesimal ,export the triangular surface deformation model by the displacement functions of triangle’ s three vertices and three sides .Finally ,this deformation model is verified by simulation ,compared with the literature methods ,this method shows that it is able to not only calculate the size but also show the direction of the strain and give the results of the strain in three directions .