Three-dimensional Finite Element Modeling of a Maxillary Premolar Tooth Based on the Micro-CT Scanning: A Detailed Description

This study describes the details of how to construct a three-dimensional （3D） finite element model of a maxillary first premolar tooth based on micro-CT data acquisition technique, MIMICS soft- ware and ANSYS software. The tooth was scanned by micro-CT, in which 1295 slices were obtained and then 648 slices were selected for modeling. The 3D surface mesh models of enamel and dentin were created by MIMICS （STL file）. The solid mesh model was constructed by ANSYS. After the material properties and boundary conditions were set, a loading analysis was performed to demonstrate the ap- plicableness of the resulting model. The first and third principal stresses were then evaluated. The re- suits showed that the number of nodes and elements of the finite element model were 56 618 and 311801, respectively. The geometric form of the model was highly consistent with that of the true tooth, and the deviation between them was ~）.28%. The loading analysis revealed the typical stress patterns in the contour map. The maximum compressive stress existed in the contact points and the maximum tensile stress existed in the deep fissure between the two cusps. It is concluded that by using the micro-CT and highly integrated software, construction of the 3D finite element model with high quality will not be difficult for clinical researchers.

Three-Dimensional Architecture of the Tongue Muscles by Micro-CT with a Focus on the Longitudinal Muscle

The purpose of this study was to show the benefit of visualizing a tree-dimensional (3D) image of the tongue’s muscle structure, which until now has been regarded as fully understood. Until now, no suitable 3D observation methods have been developed for soft tissue, such as the tongue, using?histological magnification. For this purpose, this study used a micro-computed tomographic method (micro-CT) and image processing after the fixation, decalcification, and dehydration of a mouse tongue. Results: 3D rendered images of tongue muscles obtained by micro-CT showed every muscle and their relationships to each other. The superior longitudinal and the hyoglossus muscles of the tongue made up one group, while the inferior longitudinal and the styloglossus muscles of the tongue made up another. The boundary of the two muscles in each group was difficult to distinguish. On the other hand, what appear to be newly described muscles were identified. These results indicate that our micro-CT method is beneficial and that classical knowledge of tongue muscles derived from two-dimensional (2D) images does not fully describe the actual complexity of the tongue muscles. In our opinion, 3D rendered images mixed with raw structure can provide a more in-depth picture of the tongue from an integrated as well as an analytical perspective.

Micro-computerized Three-dimensional Reconstruction of the Palmar Arteries and Its Clinical Significance

Thirty adult upper extremities were used to study the arteries of the hand byangiography,cross-sectional dissection and three-dimensional reconstruction withmicrocomputer.The arterial skeleton of the palm was composed of superficial,deep anddorsal planes.There were three main anastomotic pathways between the radial and ulnararteries or their branches in the radio-ulnar direction,while in the palmar dorsal dirce-tion there were three anastomotic zones between the palrnar and dorsal arterial plancs.The branches of the deep palmar arch radiated distally,proximally,palmarly anddorsally,so that the arch acted as the center of the arterial network of the hand.Thetransverse arterial allocations in the carpo-metacarpal segment of the palm were four intypes,but in the mid-palmar and metacarpo-phalangcal segments were three only.Accord-ing to the sources,cross-sectional area,irrigation territories and anastomoses of the ar-teries in each segment,the clinical significance in the rcplantation of the amputatcd palmshas been

A method for calibrating the confocal volume of a confocal three-dimensional micro-x-ray fluorescence setup

The measurement of the confocal volume of a confocal three-dimensional micro-x-ray fluorescence(3D-XRF)setup is a key step in the field of confocal 3D-XRF analysis.With the development of x-ray facilities and optical devices,3D-XRF analysis with a micro confocal volume will create a great potential for 2D and 3D microstructural analysis and accurate quantitative analysis.However,the classic measurement method of scanning metal foils of a certain thickness leads to inaccuracy.A method for calibrating the confocal volume is proposed in this paper.The new method is based on the basic content of the textbook,and the theoretical results and the feasibility are given in detail for the 3D-XRF mono-chromatic x-ray condition and the poly-chromatic x-ray condition.We obtain a set of experimental confirmation using the poly-chromatic x-ray tube in the laboratory.It is proved that the sensitivity factor of the 3D-XRF can be directly and accurately obtained in a real calibration process.

Three-Dimensional Architecture of the Mouse Tongue Muscles Using Micro-CT with a Focus on the Transverse, Vertical, and Genioglossus Muscles

Background: The suitability of micro-computed tomography (CT) for soft tissue applications has been well documented. Although the application of micro-CT to the three dimensional (3D) structure of the tongue muscle has been reported, a 3D rendering and/or a schematic view of the tongue muscle has yet to be published. Material and Method: First, muse tongues were fixed and decalcified, and then the vertical muscle (Ve), the transverse muscle (Tr), and/or the genioglossus muscle of the mouse tongue (Ge) were analyzed using micro-CT and are shown in this report in rendered images and pattern diagrams. Results: 1) The Tr is classified into three parts: the first part extends from the middle to the apical part of the tongue;the second part is strongly connected to the superior longitudinal muscles of the tongue (Lo);the third part fans out from the middle to the root of the tongue. 2) The Ve is classified into two main groups: the first group joins the dorsal and the lateral parts of the tongue;the second group joins the dorsal part and the floor of the tongue. 3) Ge is classified into four parts: three parts comprise the Ge apical and middle parts of the tongue, with one part in the inferior longitudinal muscles of the tongue, one joining the lingual septum of the tongue (LS), and the other joining the sub-surface of the dorsal part of the Lo. The remaining Ge exits in a fan-like manner through the root of the tongue and then joins the Tr.

A rapid micro-magnetic resonance imaging scanning for three-dimensional reconstruction of peripheral nerve fascicles

The most common methods for three-dimensional reconstruction of peripheral nerve fascicles include histological and radiology techniques. Histological techniques have many drawbacks including an enormous manual workload and poor image registration. Micro-magnetic resonance imaging（Micro-MRI）, an emerging radiology technique, has been used to report results in the brain, liver and tumor tissues. However, micro-MRI usage for obtaining intraneural structures has not been reported. The aim of this study was to present a new imaging method for three-dimensional reconstruction of peripheral nerve fascicles by ~1T micro-MRI. Freshly harvested sciatic nerve samples from an amputated limb were divided into four groups. Two different scanning conditions（Mannerist Solution/GD-DTPA contrast agent, distilled water） were selected, and both T1 and T2 phases programmed for each scanning condition. Three clinical surgeons evaluated the quality of the images via a standardized scale. Moreover, to analyze deformation of the two-dimensional image, the nerve diameter and total area of the micro-MRI images were compared after hematoxylin-eosin staining. The results show that rapid micro-MRI imaging method can be used for three-dimensional reconstruction of the fascicle structure. Nerve sample immersed in contrast agent（Mannerist Solution/GD-DTPA） and scanned in the T1 phase was the best. Moreover, the nerve sample was scanned freshly and can be recycled for other procedures. MRI images show better stability and smaller deformation compared with histological images. In conclusion, micro-MRI provides a feasible and rapid method for three-dimensional reconstruction of peripheral nerve fascicles, which can clearly show the internal structure of the peripheral nerve.

Micro-CT技术在某地下工程裂隙岩体三维显微结构表征的应用

造成地下工程开挖过程中涌突水危害的主要灾害源为导水夹泥构造。裂隙岩体渗透率主要受其内在裂隙结构与空隙分布特征影响,其中充填物的微观组分以及孔隙结构特征至关重要。以某地下工程为研究背景,通过Micro-CT技术对多组不同位置试样的孔隙结构进行表征,从微观角度诠释影响其渗透性的作用机制。X射线三维显微镜突破光学显微镜、扫描电镜等传统的表面显微成像技术方法的局限性,可以精准表征样品内部的三维显微结构,为裂隙岩体及其充填物的研究提供全新的高分辨率无损透视检测技术手段。

冷等离子体和微量润滑复合微铣削铝锂合金的表面性能研究

铝锂合金的延展性造成材料对刀具的粘附,会导致毛刺和积屑瘤等问题产生。为此,采用冷等离子体和微量润滑复合微铣削的方法加工铝锂合金,研究了工件的表面性能,并与单纯的干式、冷等离子体和微量润滑方法进行了对比。结果表明冷等离子体不仅改善了纳米流体在工件表面的浸润性,而且提高了材料的去除效率;相比于单纯的干式、冷等离子体和微量润滑方法,冷等离子体和微量润滑复合条件下的微铣削力分别降低了52.9%、42.9%和17.5%,而三维表面粗糙度Sa分别降低了67.3%、44.8%和33.3%。

增材制造小缺陷的显微CT检测

通过高精度金属增材制造技术设计制造了两组不同类型的缺陷试件,并基于显微CT检测技术和缺陷解剖金相检测方式,研究显微CT对增材制造小缺陷的实际检测能力。试验结果表明,显微CT在体素尺寸5μm下能有效检出尺寸为20μm的人工缺陷;金相检测与CT检测结果基本一致,缺陷尺寸测量差小于10μm;由于部分体积效应的影响,更小尺寸缺陷的尺寸测量结果误差更大。

基于改进卷积神经网络的心理状态预警技术

针对传统问卷法难以真实反映被调查者心理状态的问题,基于光流法和卷积神经网络提出了一种微表情判断方法,并将其作为心理状态预警技术的核心模块。对于数据集中人脸数据离散的问题,该方法采用人眼权重法对图像进行预处理,且通过金字塔光流算法提取预处理图像序列的光流特征,再利用三维卷积神经网络对该特征加以训练。与传统算法相比,所提方法在减少模型训练参数与运算时间的同时还具有更优的学习能力。实验测试结果表明,该算法在CASME数据集上的微表情识别准确率为89.2%,F1值为0.6751,均优于其他对比方法。由此证明,该算法可实现对人脸微表情的准确识别,进而为学生心理状态预警提供客观的数据支撑。

显微CT技术在钧釉瓷微观结构中的应用

X射线显微镜(显微CT)是一种非破坏性的高分辨率成像技术。采用显微CT扫描和三维重建技术,对金元时期的钧釉瓷内部气泡和孔隙进行三维可视化和定量分析,得到了三维可视化分布图像与定量数据。研究发现,金元时期钧釉瓷釉层气泡尺寸相差大,且分布离散。其中,大于100μm的气泡主要分布在釉层中层;小于100μm的气泡分布在釉层表层,通过结合岩相分析与化学组成分析发现,该特征的形成与釉的高温黏度、烧成温度等因素有关。研究采用了显微CT扫描与三维重建技术,其是一种无损分析古陶瓷气泡与孔隙特征及工艺的新方法,该研究验证了显微CT在古陶瓷微观结构研究中的可行性和有效性,为古陶瓷制作工艺的科学分析、鉴定、保护和修复等方面提供重要的实验依据。

Micro CT评估光照模式对复合树脂微渗漏影响的研究

目的:用Micro CT评价不同光照模式对复合树脂充填体微渗漏的影响。方法:选取24颗新鲜拔除的上颌前磨牙,在牙冠颊面制备圆形窝洞(直径1 mm,深度1 mm),窝洞用光固化树脂(3M Z250)充填并固化,按照光固化模式随机分为常规模式组(A组)、弱光引导组(B组)、间歇光照组(C组)。标本经冷热循环及氨硝酸银染色剂浸染后,用Micro CT测量复合树脂充填体和牙齿界面的银沉积物体积,定量评价微渗漏程度。结果:常规模式组微渗漏大于弱光启动组和间歇光照组,差异有显著性(P<0.05);弱光启动组与间歇光照组之间微渗漏有差异,但不具统计学意义(P>0.05)。结论:弱光引导模式和间歇光照模式能够比常规光照模式更有效降低复合树脂(3M Z250)的微渗漏。

微热压成形石墨件的快速碳化工艺

针对石墨件在碳化过程中易开裂的问题,基于多材料组装技术原理,提出在石墨粉末微热压成形过程中构造烧蚀性二维有机物网络以形成排气通道、避免开裂的方法。研究了碳化速率、石墨件径向尺寸及网络结构、分布方式对石墨件成形质量和力学性能的影响。结果表明:较快的碳化速率会加剧有机物热解,开裂的现象越明显,较大径向尺寸的石墨件气体逸出阻力越大;提高有机物网络密集度有助于改善排气效果,但对石墨件力学性能产生不利影响;在有机物网络沿成形高度方向的布置中,当间距为10 mm时,石墨件不出现裂纹。采用优化的工艺制备的石墨件结构完整,经过浸渍增强后其抗压强度达到15.8 MPa,Z轴导热系数仅为1.894 W/(m·K),综合性能与水玻璃型砂相当,在铸造行业有广泛应用前景。

熔体黏弹特性对模内微装配成型制造精度影响

针对微细万向球形转动运动副的功能自润滑液膜辅助模内微装配成型,明晰其微装配界面直径制造公差—黏弹性热流固耦合冲击载荷、连续相变演化区厚度、热黏弹塑性应力—熔体黏弹弹性的多场协同耦合演化规律,是实现精密调控其制造精度的关键技术问题。结果表明,微装配界面直径制造公差受控于二次注射成型充填熔体的黏弹特性,当参考黏度由2267 Pa·s增至15000 Pa·s时,微装配界面直径制造公差由11μm增至19μm,增幅为72.7%;而当松弛时间由0.05 s增至0.25 s,则由31μm减至19μm,减幅38.7%;为了满足行业规范的尺寸制造公差技术指标≤30μm的要求,不宜采用松弛时间小于0.05 s的高弹性熔体进行其功能自润滑液膜辅助模内微装配成型。

基于MICRO-CT的乳前牙三维模型重建

目的:利用Micro-CT对离体乳切牙和乳尖牙进行扫描和三维重建。方法:运用Micro-CT对标本牙进行扫描,结合Amira软件进行三维重建,获得标本牙不同结构的牙齿三维模型和数字图像。结果:用此方法成功构建出标本乳切牙和乳尖牙的三维模型,清晰展示出标本牙不同结构在整体中的位置、层次和形态特点,摸索出一套对乳牙行之有效、快捷、准确的建模方法。结论:对乳牙多个牙位尤其是乳前牙的三维模型开展研究,填补了乳牙内部解剖资料稀缺的空白,为临床治疗提供了参考。

Micro-CT三维重建技术在根管治疗研究中的应用

熟悉根管系统的解剖形态特征、彻底的根管预备和严密的根管充填是根管治疗成功的重要保障。随着医学影像学技术的发展,三维影像重建技术已广泛应用于根管形态学、根管预备效果、根管充填质量、根管再治疗效率、三维有限元力学等相关研究。通过不同角度和层面观察和定性定量地分析三维重建后的根管三维图像,了解根管解剖形态,评价根管治疗各个环节的操作效果,对于临床操作具有重要的指导意义。本文就基于Mirco-CT的三维重建技术在根管解剖形态、根管预备、根管充填、根管再治疗效率以及三维有限元力学等研究中的应用作一综述。文献综述结果表明,Micro-CT分辨率高,Micro-CT扫描三维重建后的立体影像能精确地显示根管的细微解剖形态;准确测算根管预备前后的根管体积和形态变化、根管充填后的空隙发生率和空隙体积;准确计算根管再治疗前后根管充填材料的体积变化,是目前根管系统形态学研究和评价根管预备和充填质量的金标准。Micro-CT扫描三维重建后,可建立三维有限元模型,模拟根管治疗的过程并进行应力分析,分析根管治疗器械应力分布和根管预备对牙体组织应力的影响、根管充填过程中根管壁的应力分布等,从而筛选合适的操作方法、预防器械折断及牙根的折裂。Micro-CT三维重建技术在根管形态及根管治疗评价中具有重要价值。

易混淆中药地骨皮、香加皮、五加皮鉴别研究

目的:探讨区分鉴别易混淆皮类中药地骨皮、香加皮、五加皮的方法。方法:采用性状、微性状、显微、荧光鉴别等方法对地骨皮、香加皮、五加皮进行鉴别研究。结果:地骨皮、香加皮、五加皮在性状和微性状方面的主要鉴别点是外表面、断面和气味;显微鉴别的重点是草酸钙结晶不同。传统荧光法在紫外灯下观察三者的荧光现象区别不明显,但是二维荧光和三维荧光等方面均有较大差异。二维荧光光谱结果显示,三种药材的水提取液均只有一个荧光峰,三者的峰位、峰强度和峰形有很大差别;三维荧光光谱结果显示,地骨皮有三个荧光峰,香加皮和五加皮有两个荧光峰,三者的峰位和峰强度有明显差异。结论:传统鉴别方法可用于地骨皮、香加皮、五加皮的鉴别,二维荧光光谱法和三维荧光光谱法可快速、准确地区分三种药材。

基于MICRO-CT的下颌第二乳磨牙三维模型重建

目的:构建经由Micro-CT扫描的离体下颌第二乳磨牙的三维模型,并实现网络共享。方法:用MicroCT对离体下颌第二乳磨牙进行扫描并三维重建,获得整颗牙及不同结构的三维模型。结果:用此方法成功构建出下颌第二乳磨牙的三维模型,清晰展示出此牙的牙釉质、牙本质、牙骨质及牙髓的形态及上述结构之间的位置关系。结论:经由Micro-CT高精度扫描后获取的三维模型填补了乳牙内部解剖资料稀缺的空白,为临床治疗提供了参考,同时为儿童口腔医学的基础教学方式提出创新思路。

基于多尺度时空注意力网络的微表情检测方法

微表情可以揭示人们试图隐藏的真实情绪,为刑事侦查、心理辅导等提供潜在的信息。现有微表情检测方法主要在获取空间特征的基础上提取时间特征以构建时空特征,这种处理方式容易导致时间特征失真,同时在空间处理过程中会破坏原有时序关系,降低微表情时空特征的判别性。针对这一问题,提出基于多尺度时空注意力网络的微表情检测方法。利用包含时间和空间关系的三维卷积神经网络(3DCNN)对微表情序列进行处理,获取兼顾时间域和空间域的鲁棒性特征。构建多尺度时间输入序列,从不同时间长度的图像序列中提取多维时间特征,采用轻量级3DCNN提取多尺度时空特征,利用全局时空注意力模块(GSAM)对时空特征进行全局性时空关联加强,其中时空重组模块用于加强不同时刻图像帧之间的连通性,全局信息关注模块构建单帧图像上的空间关联信息,最后对不同时刻的特征赋予权重以突出关键时间信息,有效完成微表情检测工作。实验结果表明,该方法可以准确检测出微表情序列片段,在CASME、CASME II和SAMM公开数据集上的准确率分别达到92.32%、95.04%和89.56%,相比目前最优的深度学习方法LGAttNet,所提方法在CASME II和SAMM数据集上的准确率分别提高了3.84和4.96个百分点。

仿生双相磷酸钙生物陶瓷支架的Micro-CT评价

[目的]体外用MicroCT(Microcomputedtomography)图像对仿生双相磷酸钙生物陶瓷支架的三维结构进行计算机重建和评价。[方法]犬股骨头的松质骨样本行MicroCT扫描,提取图像信息;三维凝胶叠层成型法制备出具有仿骨小梁结构的双相磷酸钙仿生生物陶瓷支架。随后用MicroCT对支架扫描,以三维结构参数对支架和松质骨样本作三维评价和比较。三维参数包括骨体积分数(BoneVolumeFraction,BVF,BV/TV)、骨表面积体积比(Bonesurface/bonevolumeratio,BS/BV)、骨小梁厚度(Trabecularthickness,TbTh)、骨小梁数目(Trabecularnumber,TbN)、骨小梁间隙(Trabecularspacing,TbSp)、结构模型指数(StructureModelIndex,SMl)和各向异性程度(degreeofanisoropy,DA)。[结果]与犬股骨头松质骨样本相比,用本方法制备出的BCP支架具有相似的三维空间结构,二者的BV/TV、TbTh、TbN无显著差别(P>0.05)。小梁结构呈板状模型。[结论]本研究制备的BCP多孔支架的小梁具有一定的取向性,力学强度和良好的适于血管长入的空间结构。