脑缺血疾患颈动脉彩色多普勒超声检查

目的 :探讨二维彩色多普勒超声及彩色血管三维超声在颈动脉疾病的诊断价值。材料方法 :疑为缺血性脑卒中患者 80例 ,行颈动脉彩色多普勒超声检查 ,其中 2 8例同时做彩色血管三维超声成像 ,5 5例经临床、CT、MRI证实为脑梗死。结果 :①本组 5 5例脑梗死 ,彩色多普勒超声发现 4 9例颈动脉粥样硬化斑。②有脑梗死的彩色血管三维血流图呈“串珠”状 ,而非脑梗死的彩色血管三维血流图呈连续“圆锥”状。结论 :彩色多普勒超声诊断颈动脉粥样硬化有良好的价值 ,三维彩超是二维彩色多普勒超声的有益补充。     

Vascular Centerline Extraction in 3D MR Angiograms for Phase Contrast MRI Blood Flow Measurement

The accuracy of 2D phase contrast (PC) magnetic resonance angiography (MRA) depends on the alignment between the vessels and the imaging plane. PC MRA imaging of blood flow is challenging when the flow in several vessels is to be evaluated with one acquisition. For this purpose, semi-automatic determination of the plane most perpendicular to several vessels is proposed based on centerlines extracted from 3D MRA. Arterial centerlines are extracted from 3D MRA based on iterative estimation-prediction, multi-scale analysis of image moments, and a second-order shape model. The optimal plane is determined by minimizing misalignment between its normal vector and the centerlines’ tangent vectors. The method was evaluated on a phantom and on 35 patients, by seeking the optimal plane for cerebral blood flow quantification simultaneously in internal carotids and vertebral arteries. In the phantom, difference of orientation and of height between known and calculated planes was 1.2° and 2.5 mm, respectively. In the patients, all but one centerline were correctly extracted and the misalignment of the plane was within 12° per artery. Semi-automatic centerline extraction simplifies and automates determination of the plane orthogonal to one vessel, thereby permitting automatic simultaneous minimization of the misalignment with several vessels in PC MRA.     

铰链式冠外附着体的结构强度分析

目的探讨铰链式冠外附着体设计的合理性.方法采用有限元应力分析的实验方法,分析铰链式冠外附着体阳性结构L形球体的应力分布情况,对其结构强度进行测试.结果在附着体阳性结构L形球体的转角处应力最大,应力值为321.847MPa.结论该铰链式附着体的结构强度符合临床设计要求.     

冠心病患者血糖与微量元素的相关性研究

为探讨冠心病患者血糖与微量元素的关系，用电感耦合等离子体原子发射光谱法测定了７８例冠心病患者的６种微量元素变化，并与血糖做相关分析．结果冠心病患者高血糖组与正常血糖组相比，血清铁、铅、镉显著增高，锌和铬显著降低，Ｐ＜００５或００１，铜无显著性差异；血糖与血清铁、铅呈显著性正相关，与血清铬、锌呈显著负相关，而与铜、镉相关不显著．表明部分微量元素的不平衡构成对冠心病的危险因子———高血糖的促发作用，调整人群中微量元素的不平衡状态，对减少冠心病及糖尿病的发生可能有利     

血管内支架模型及离体血管经腔内超声三维重建的实验研究

我们自制了16个不同形状和大小的金属支架模型，置入人造血管腔中，并采用高体正常血管8条（犬腹主动脉4条，人冠状动脉4条）进行经血管腔内超声显像（IVUS）的体元模型三维重建（3DR）研究。结果显示，该技术能真实地再现支架在管腔内的形态、支架与管壁之间的间隙及离体正常血管的管腔及管壁形态，经提取后重建的支架模型与实物非常相似。经3DR测得的支架及血管腔内径与实测值均高度相关（r分别为0.96和0.99，p＜0．001）。支架与管壁之间空隙的3DR测值与实测值也高度相关（r=0.97，p＜r.0.01）。     

特发性甲状旁腺功能低下（附13例分析）

本文观察分析了13例特发性甲状旁腺功能低下患者、查PTH6例。患者血清中除有本病低血钙、高血磷的固有特征外，其它微量元素也有改变，如血清镁值减低。这与文献[1]的报道相符。碱性磷酸酶2例明显升高。磷廓清率S例降低。肾小管磷重吸收率5例升高。放免甲功：抗甲状腺微粒体2例升高。T细胞亚群1例低于正常值。本病有家族性，与遗传有关。     

Mouthguards: difference in longitudinal dimensional stability between single- and double-laminated fabrication techniques

Abstract –  Though the use of mouthguards (MGs) has increased with the increase in sporting activities, little is known about the influence of their fabrication methods on longitudinal dimensional stability. The objective of this study was to compare the difference in the longitudinal dimensional stability between single and laminated MGs. Single-layer MGs were made from a 4.0 mm thick ethylene vinyl acetate (EVA) sheet and laminated MGs were made from two 2.0 mm thick sheets of EVA. MGs were kept in a 37°C water bath for 60 h, equivalent to the time period of 3-months inter-oral use. MG deformation was analyzed by measuring designated points on the MG border using a profile projector (J-12, Nikon Inc., Tokyo, Japan) before and after the water immersion. A finite-element model was also created to examine the time course of stress accumulation during the sheet forming process using Finite Element software. Longitudinal deformation was smaller in the laminated MGs than in the single-layer MGs in the anterior area ( P  < 0.05). Finite element method (FEM) analysis also showed the largest stress accumulation in the anterior incisal area where deformations were mainly observed. Laminated double layer MGs have advantages over single-layer MGs in terms of longitudinal stability due to lower stress accumulation during the fabrication process.     

下前牙桩核冠三维有限元模型的建立

目的：建立桩核冠修复后的下颌中切牙及其牙周支持组织的三维有限元模型。方法：利用薄层CT技术、UG软件与ALGOR软件相结合，对层厚为0．2mm的CT断层影像进行分析处理。结果：模型共有单元45153个，节点27763个，可以根据要求任意旋转、缩放、透视、剖开，进行多种方式观察；并可以按照不同研究目的，对模型进行修改和调整，来模拟不同程度牙槽骨吸收、联冠修复以及各种约束和加载条件下前牙的力学反应。结论：利用薄层CT扫描技术、UG自由曲面功能以及ALGOR软件相结合建立的三维有限元模型，能较精确地模拟临床口腔实际情况，为进一步研究下颌前牙不同牙周情况下的修复奠定了良好的基础。     

股骨头骨坏死样本空间结构的Micro-CT评估

目的以股骨头骨坏死样本的Micro-CT断层图像为基础，对其进行空间结构评估。方法2003年11月～2005年6月，收集股骨头骨坏死患者行全髋关节置换术时取出的股骨头样本6个，对样本进行Micro-CT断层扫描，获取股骨头骨坏死样本的计算机三维图像，图像空间分辨率为36μm×36μm×36μm。手工选取兴趣区，随后采用骨体积分数（BV／TV）、骨小梁间隙（Tb．Sp）、骨小梁厚度（Tb，Th）、骨小梁数目（Tb．N）、骨表面积体积比（BS／BV）、结构模型指数（SMI）、骨小梁模型因子（Tb．Pf）等三维空间参数分别对股骨头骨坏死标本的正常区域、硬化带和塌陷区进行评价。结果晚期股骨头骨坏死硬化区和塌陷区的骨小梁空间结构明显改变：硬化区Bv／Tv明显增加，Tb．Th明显增厚，Tb，Sp变窄，SMI与正常区域的骨小梁无差别；而塌陷区Bv／Tv明显减少，BS／BV增大，Tb．N和Tb．Pf增加，Tb，Th改变不明显。结论Micro-CT作为一种新的检测手段，能够在不损伤样本的条件下快速获取股骨头骨坏死样本断层图像，具有精度高、检测快、可进行三维重建分析的优点。晚期股骨头骨坏死不同区域的骨三维结构呈现出不同的空间结构特征。     

三维CT脑血管造影在脑动脉瘤诊断中注意点

目的探讨三维CT脑血管造影(3D-CTA)在诊断脑动脉瘤时的注意事项。方法回顾总结3D-CTA检查的106例蛛网膜下腔出血(SAH)病例,其中14例初次3D-CTA显示动脉瘤不清或发现颅内非动脉瘤样血管异常者,对其进行DSA脑血管造影检查。结果初次3D-CTA检查正确诊断脑动脉瘤92例,其中16例为多发脑动脉瘤,共检出115个。余14例因诊断不明确进而实施DSA脑血管造影检查,其中确诊动脉瘤合并烟雾病2例、严重脑血管痉挛致动脉瘤显示不清2例、脑动静脉畸形1例(此5例与3D-CTA所见一致);在3D-CTA扫查范围外发现脑动脉瘤2例。对上述阳性诊断的99例进行手术,并得到证实。另7例在3D-CTA和DSA检查未发现引起SAH的原因病灶,给予保守治疗。结论在脑动脉瘤诊断中,3D-CTA具有较好的精确性。在判断动脉瘤与颅骨位置关系、操作的便捷性和经济性等方面明显优于DSA。在应用3D-CTA对脑动脉瘤进行诊断时,有必要根据患者和设备的具体情况进行个性化设计,方能减少漏诊、误诊。