Micro-Computed Tomography Applications in Dentistry

Micro-computed tomography (MCT) encompasses two primary scanning options: ex-vivo and in-vivo imaging. Ex-vivo scanning involves the examination of extracted teeth or dental specimens, allowing for detailed analyses of the microarchitecture of mineralized tissue. By analyzing the microarchitecture of dental tissues, MCT can provide valuable information about bone density, porosity, and microstructural changes, contributing to a better understanding of disease progression and treatment outcomes. Moreover, MCT facilitates the quantification of dental parameters, such as bone volume, trabecular thickness, and connectivity density, which are crucial for evaluating the efficacy of dental interventions. This present study aims to comprehensively review and explore the applications of MCT in dentistry and highlight its potential in advancing research and clinical practice. The results depicted that the quantitative approach of MCT enhances the precision and reliability of dental research. Researchers and clinicians can make evidence-based decisions regarding treatment strategies and patient management, relying on quantifiable data provided by MCT. The applications of MCT in dentistry extend beyond research, with potential clinical implications in fields such as dental implantology and endodontics. MCT is expected to play an increasingly significant role in enhancing our understanding of dental pathologies, improving treatment outcomes, and ultimately, benefiting patient care in the field of dentistry.

基于Micro-CT的BALB/c小鼠肺腺瘤动物模型研究

目的 建立基于Micro-CT动态表征的BALB/c小鼠肺腺瘤动物模型研究方法。方法 取80只SPF级雌性BALB/c小鼠,随机分为4组:模型低剂量组(1 mg/g乌拉坦腹腔注射1次)、模型中剂量组(1 mg/g乌拉坦腹腔注射,每周1次,连续2周)、模型高剂量组(1 mg/g乌拉坦腹腔注射,每周1次,连续4周)和空白组(等体积生理盐水腹腔注射)。采用Micro-CT定期监测小鼠肺结节生长情况,Analyze 12.0分析系统绘制小鼠肺部3D图像,苏木素-伊红(HE)染色观察肺组织病理学变化。结果 与空白组相比,各模型组小鼠第11周时均观测到类圆形高密度影的肺结节。结节形成率随造模周数增加而升高,至第21周时,模型高、中、低剂量组结节形成率分别为93.8%、93.8%、87.5%;结节数分别以2~4个、1个、1~2个为主;低剂量组肺结节最大直径平均值高于中、高剂量组(P<0.05);肺结节体积三组之间差异无统计学意义。HE染色结果显示模型高、中、低剂量组病理类型均为肺腺瘤。结论 模型各剂量组均成功诱导肺腺瘤,Micro-CT可对小鼠肺结节生长情况进行表征,其中模型中剂量组结节形成率高,肺腺瘤数量适中,模型稳定,更适合小鼠肺腺瘤动物模型的研究。

Assessing efficacy of standard impregnation techniques on die-cast aluminum alloys using X-ray micro-CT

Utilizing lightweight Al alloys in various industrial applications requires achieving precise pressure tightness and leak requirements.Vacuum pressure impregnation(VPI)with thermosetting polymers is commonly used to address leakage defects in die-cast Al alloys.In this study,the efficacy of the VPI technique in sealing alloy parts was investigated using a combination of nondestructive micro X-ray computed tomography(micro XCT)and a standard leak test.The results demonstrate that the commonly used water leak test is insufficient for determining the sealing performance.Instead,micro XCT shows distinct advantages by enabling more comprehensive analysis.It reveals the presence of a low atomic number impregnates sealant within casting defects,which has low grey contrast and allows for visualizing primary leakage paths in 3D.The effective atomic number of impregnated resin is 6.75 and that of Al alloy is 13.69 by dual-energy X-ray CT.This research findings will contribute to enhancing the standard VPI process parameters and the properties of impregnating sealants to improve quality assurance for impregnation in industrial metals.

Characterization of microstructure evolution of cement paste by micro computed tomography

Micro computed tomography (Micro-CT) was applied to obtain three-dimensional images of the microstructure of cement paste (water-to-cement mass ratio of 0.5) at different ages. By using the Amira software, component phases of the cement paste such as pores, hydration products, and unhydrated clinker particles were segmented from each other based on their 3D image grey levels; their relative contents were also calculated with the software, and the data are 61.2%, 0% and 38.8% at the beginning of hydration and 11.8%, 78.5% and 9.7% at 28 d age, respectively. The hydration degree of cement paste at different ages was compared with the experimental data acquired by loss on ignition (LOI) tests. The results show that the calculated and measured data reasonably agree with each other, which indicates that micro-CT is a useful and reliable approach to characterize the micro structure evolution of hydrating cement paste.

Effects of dry-wet cycles on three-dimensional pore structure and permeability characteristics of granite residual soil using X-ray micro computed tomography

Due to seasonal climate alterations,the microstructure and permeability of granite residual soil are easily affected by multiple dry-wet cycles.The X-ray micro computed tomography(micro-CT)acted as a nondestructive tool for characterizing the microstructure of soil samples exposed to a range of damage levels induced by dry-wet cycles.Subsequently,the variations of pore distribution and permeability due to drywet cycling effects were revealed based on three-dimensional(3D)pore distribution analysis and seepage simulations.According to the results,granite residual soils could be separated into four different components,namely,pores,clay,quartz,and hematite,from micro-CT images.The reconstructed 3D pore models dynamically demonstrated the expanding and connecting patterns of pore structures during drywet cycles.The values of porosity and connectivity are positively correlated with the number of dry-wet cycles,which were expressed by exponential and linear functions,respectively.The pore volume probability distribution curves of granite residual soil coincide with the χ^(2)distribution curve,which verifies the effectiveness of the assumption of χ^(2)distribution probability.The pore volume distribution curves suggest that the pores in soils were divided into four types based on their volumes,i.e.micropores,mesopores,macropores,and cracks.From a quantitative and visual perspective,considerable small pores are gradually transformed into cracks with a large volume and a high connectivity.Under the action of dry-wet cycles,the number of seepage flow streamlines which contribute to water permeation in seepage simulation increases distinctly,as well as the permeability and hydraulic conductivity.The calculated hydraulic conductivity is comparable with measured ones with an acceptable error margin in general,verifying the accuracy of seepage simulations based on micro-CT results.

Investigating microstructure of Longmaxi shale in Shizhu area,Sichuan Basin, by optical microscopy, scanning electron microscopy and micro-computed tomography

Microstructure of shale formation is the key to understanding its petrophysical and chemical properties.Optical microscopy, scanning electron microscopy and micro-computed tomography(μ-CT) have been combined for characterization of microstructure of Longmaxi(LMX)shale from Shizhu area, Sichan Basin. The results indicate that laminated LMX shale consists of mineral matrix-rich layers and organic matter(OM)-rich layers at micrometer scale in two and three dimensions. Mineral matrix layers,mainly consisting of interparticle pores and intraplatelet pores, are approximately parallel to the bedding plane.Pyrite-rich layer, mainly containing intercrystalline pores,shows a strong preferred orientation parallel to the bedding plane. OM-rich layer, mainly containing OM pores, seems to be discontinuous. In addition, intercrystalline pores are enriched in some layers, while OM pores are distributed irregularly in matrix layers. This vertical heterogeneity of pore microscopic structures in LMX shale is of great importance to understand its petrophysical and chemical properties.

Comparative study of chitosan/fibroin–hydroxyapatite and collagen membranes for guided bone regeneration in rat calvarial defects: micro-computed tomography analysis

This study aimed to utilize micro-computed tomography （micro-CT） analysis to compare new bone formation in rat calvarial defects using chitosan/fibroin-hydroxyapatite （CFB-HAP） or collagen （Bio-Gide） membranes. Fifty-four （54） rats were studied. A circular bony defect （8 mm diameter） was formed in the centre of the calvaria using a trephine bur. The CFB-HAP membrane was prepared by thermally induced phase separation. In the experimental group （n= 18）, the CFB-HAP membrane was used to cover the bony defect, and in the control group （n= 18）, a resorbable collagen membrane （Bio-Gide） was used. In the negative control group （n= 18）, no membrane was used. In each group, six animals were euthanized at 2, 4 and 8 weeks after surgery. The specimens were then analysed using micro-CT. There were significant differences in bone volume （BV） and bone mineral density （BMD） （P〈O.05） between the negative control group and the membrane groups. However, there were no significant differences between the CFB-HAP group and the collagen group. We concluded that the CFB-HAP membrane has significant potential as a guided bone regeneration （GBR） membrane.

Nondestructive Skeletal Imaging of Hyla suweonensis Using Micro-Computed Tomography

We successfully obtained 3D skeletal images of Hyla suweonensis, employing a nondestructive method by applying appropriate anesthesia and limiting the radiation dose. H. suweonensis is a tree frog endemic to Korea and is on the list of endangered species. Previous studies have employed caliper-based measurements and two-dimensional （2D） X-ray imaging for anatomical analyses of the skeletal system or bone types of H. suweonensis. In this work we reconstructed three-dimensional （3D） skeletal images of H. suweonensis, utilizing a nondestructive micro-computed tomography （micro-CT） with a short scan and low radiation dose （i.e. 4 min and 0.16 Gy）. Importantly, our approach can be applied to the imaging of 3D skeletal systems of other endangered frog species, allowing both versatile and high contrast images of anatomical structures without causing any significant damages to the living animal.

Contrast-enhanced micro-computed tomography using Exi Tron nano6000 for assessment of liver injury

AIM: To explore the potential of contrast-enhanced computed tomography(CECT) using Exi Tron nano6000 for assessment of liver lesions in mouse models.METHODS: Three mouse models of liver lesions were used: bile duct ligation(BDL),lipopolysaccharide(LPS)/D-galactosamine(D-Gal N),and alcohol.After injection with the contrast agent Exi Tron nano6000,the mice were scanned with micro-CT.Liver lesions were evaluated using CECT images,hematoxylin and eosin staining,and serum aminotransferase levels.Macrophage distribution in the injury models was shown by immunohistochemical staining of CD68.The in vitro studies measured the densities of RAW264.7 under different conditions by CECT.RESULTS: In the in vitro studies,CECT provided specific and strong contrast enhancement of liver in mice.CECT could present heterogeneous images anddensities of injured livers induced by BDL,LPS/D-Gal N,and alcohol.The liver histology and immunochemistry of CD68 demonstrated that both dilated biliary tracts and necrosis in the injured livers could lead to the heterogeneous distribution of macrophages.The in vitro study showed that the RAW264.7 cell masses had higher densities after LPS activation.CONCLUSION: Micro-CT with the contrast agent Exi Tron nano6000 is feasible for detecting various liver lesions by emphasizing the heterogeneous textures and densities of CECT images.

Microstructure Study of Normal Lunates with Micro-computed Tomography

In order to study the microstructure characteristics of normal lunate bones, eight fresh cadaver normal lunates were scanned with micro-computed tomography. High-resolution images of the micro-structure of normal lunates were obtained and we analyzed the nutrient foramina. Then nine regions of interest(ROI) were chosen in the central sagittal plane so that we could obtain the parameters of trabecular bones of ROIs. The distal lamellar-like compact structure had statistically significant differences when it was compared with the ROIs in the volar and dorsal ends of the distal cortex. The difference of diameter between the volar and dorsal foramina was significant(P<0.05). However, there was no significant difference regarding the number. The trabecular bones of the volar and dorsal distal ends had lower intensity than those of the distal central subchondral bone plate. The diameters of the nutrient foramina on the volar cortex were larger than those on the dorsal. This research provided more detailed information about microstructure of normal lunate and the nutrient foramina on cortex, and a reference for further study about diseased lunate.

Monitoring vascular changes induced by photodynamic therapy using contrast-enhanced micro-computed tomography

The aim of this study was to determine whether contrast-enhanced micro-computed tomography can be used for non-invasive imaging of the early-stage changes in the vasculature of tumours that have been treated with photodynamic therapy (PDT). The subjects used were C3H mice with an RIF-1 tumour implanted subcutaneously and allowed to grow for 3 weeks prior to treatment. The experimental groups were PDT-treated (150 J/cm2 and 50 J/cm2) and control (150 J/cm2 light-only and untreated). The laser light exposure was performed at 15 - 30 minutes after the administration of the photosensitizer (BPD-MA). The contrast-enhanced micro-computed tomography imaging procedure consisted of eight-second scans taking place before treatment and up to 24 hours after treatment. The 150 J/cm2 PDT group showed a significant increase in the ratio of blood volume to tumour volume at 2, 8 and 24 hours after treatment when compared to pre-treatment measurements (p 2 PDT group at 24 hours after treatment. This preliminary study indicates that micro-CT can detect compromised vasculature in tumours treated with high-fluence photodynamic therapy as early as 2 hours post treatment.

Micro CT检测小鼠骨微结构指标受标本通量影响的方案设计

在过去几十年中,Micro CT已成为评估小动物骨骼微结构的金标准。然而Micro CT得到的定量指标会受到很多因素影响,如成像参数、重建像素大小和图像分割阈值等。为了提高相关实验准确性和可重复性,以及在各个研究间进行更可靠的比较,结合小鼠离体股骨的Micro CT实验,设计不同通量的标本及组合方案来验证骨微结构测量结果是否受其影响。结果表明,标本通量及组合方式的不同对骨微结构指标测量没有产生显著性影响,但高通量扫描会降低输出图像的质量,可能会减弱组间差异的检测能力,仍需注意其产生的影响。因此在确定实验方案前需探讨标本通量对实验结果是否产生影响,或者在整个研究中保持标本通量和标本摆放方式的一致性。

Micro-CT技术结合逆向工程软件建立上颌第一前磨牙的三维有限元模型

目的利用简便有效的方法建立离体上颌第一前磨牙三维有限元模型,为生物力学研究提供数学模型基础。方法使用Micro-CT对离体、完整的左侧上颌第一前磨牙进行牙体扫描,将获得的CT影像转化格式,通过Mimics10.0软件采集釉质、本质及髓腔的点数据,导入Imageware 12.0软件中进行点云处理和曲线反求,通过Ansys 11.0软件完成曲面拟合形成牙体组织的三维实体模型并进行布尔运算,整合釉质、牙本质及髓腔系统;建立牙周膜以及牙槽骨的实体模型,分别进行网格划分,同时对模型进行力学加载。结果建立了包含髓腔、牙周膜、牙槽骨的上颌第一前磨牙的精细三维有限元模型,网格划分后的牙体三维有限元模型:釉质具有26 685个单元,牙本质具有114 082个单元,牙髓腔具有11 843个单元,牙周膜具有22 004个单元,牙槽骨具有66 767个单元,共有241 381个10节点四面体单元。模型具有非常高的精确度,真实反映了釉牙骨质界的形态。从应力分布来看釉质上应力主要集中在面中央窝和釉质与本质交界的边缘;同样牙本质的应力集中部分也在釉牙本质界处。结论通过Micro-CT技术与逆向工程软件相结合的方法建立了左侧上颌第一前磨牙的三维有限元模型,该模型具有良好的几何相似性和力学相似性。

骨质疏松性椎体压缩骨折的Micro-CT影像学参数分析

目的初步探讨骨质疏松性椎体压缩骨折患者、骨质疏松患者以及无骨质疏松患者3者间椎体骨质的差别。方法对30例需要进行手术治疗的患者进行分组,分别为骨质疏松性椎体压缩骨折患者组、骨质疏松患者组及无骨质疏松患者组,每组10例。在术中分别取出3组患者少许椎体样本,椎体样本大小相等,不影响手术疗效的同时亦不会对患者造成不良影响,患者均表示知情同意。随后分别对取出的椎体标本进行显微计算机断层扫描术(micro-computed tomography,Micro-CT)检测,以了解及对比3组患者之间椎体骨密度(bone mineral density,BMD)、骨矿含量(bone mineral content,BMC)和骨小梁情况。结果骨质疏松性椎体压缩骨折患者组对比骨质疏松患者组、无骨质疏松患者组其椎体皮质骨BMD、松质骨BMD、骨小梁BMD和总体BMD以及皮质骨BMC、松质骨BMC和总BMC均有明显下降,差异具有统计学意义(P<0.05),其中骨小梁BMD、皮质骨BMC、松质骨BMC和总BMC下降显著(P<0.01);骨质疏松患者组对比无骨质疏松患者组其椎体皮质骨BMD、松质骨BMD、骨小梁BMD和总体BMD以及皮质骨BMC、松质骨BMC和总BMC均有下降,差异具有统计学意义(P<0.05),其中骨小梁BMD下降显著(P<0.01)。结论较低的椎体BMD和BMC是椎体压缩骨折发生发展的主要原因,骨质疏松患者和暂无骨质疏松人群需要预防BMD、BMC的下降,防止骨质疏松性椎体压缩骨折的发生。

基于Micro-CT光机X射线源的单晶LaB_6阴极的制备及其性能研究

本文采用电化学腐蚀方法和聚焦离子束技术制备了单晶LaB_6针尖,借助电子扫描电镜对针尖进行微观形貌分析。在此基础上,研制热解石墨径向夹持直热式单晶La B6阴极,对其发射性能及其在Micro-CT应用进行研究。研究表明,单晶LaB_6阴极能够产生高亮度的电子束,提高了X射线亮度,提升了Micro-CT图像质量。

Micro-CT技术及其在植物学研究中的应用

微CT技术已成为医学和生物等领域重要的研究手段,但在植物和农林科学领域的应用才刚刚起步。为了让植物和农林领域研究人员能更充分、灵活地运用微CT技术,提高仪器应用效果,拓展仪器使用需求,该文介绍了微CT技术基本原理、样品制备和分析流程。最后以稻谷为例,应用Mimics软件分析断层图,并开展三维重组和结构分析。该文可为科研工作者利用微CT技术分析植物样本提供参考,以便更好地服务于教学和科研工作。

带根面沟下颌第一前磨牙V型根管形态的Micro-CT研究

目的:使用Micro-CT技术研究离体带根面沟下颌第一前磨牙V型根管系统形态。方法:收集58颗带根面沟下颌第一前磨牙,运用Micro-CT扫描后三维重建牙齿及根管系统形态,观测根管类型、Vertucci V型根管分叉位置及角度,统计侧副根管发生率及位置;并对颊、舌根管根尖孔位置、管壁厚度及根管直径进行比较分析。结果:带根面沟下颌第一前磨牙根管最常见的类型为Vertucci V型,发生率为55.2%,有1例罕见4根管类型:1-3-4-3型;分叉至釉质牙骨质界距离为(6.13±2.08)mm,其舌侧根管偏离主根管角度为29.89°±11.22°;V型根管颊舌两根管在根尖孔位置、管壁厚度及根管直径方面均有统计学差异(P<0.05)。结论:带根面沟下颌第一前磨牙根管系统解剖形态复杂,V型根管发生率较高,了解其根管解剖特点,可为临床牙体治疗和修复提供参考。

基于Micro-CT成像对肝癌原位移植瘤血管三维结构的定量研究

目的基于Micro-CT成像定量肝癌裸鼠原位移植瘤血管的三维结构特征。方法采用雄性Balb/c裸小鼠20只,随机分为肝癌组(n=10)和正常对照组(n=10),肝癌组采用MHCC97H人肝癌细胞株构建原位移植瘤模型,正常对照组肝内注射同等量0.9%氯化钠溶液。造模21 d后进行目标血管铸型和Micro-CT扫描,重建血管图像,观察肝癌和正常肝脏血管的三维形态并定量分析血管密度特征、血管形态特征上的差异。结果正常肝脏血管呈树枝状逐级分支,走行自然;肝癌血管分布杂乱,形态不规则。定量分析结果显示,相比于正常肝脏,肝癌的血管占比[(5.57±1.16)%比(14.29±2.89)%,P<0.01]、血管分支密度[(3.86±1.15)比(7.25±3.30),P=0.007]明显降低,平均半径缩小[(0.17±0.03)mm比(0.22±0.04)mm,P=0.004],平均DF[(1.20±0.01)比(1.16±0.00),P<0.01]、平均SOAM[(4.56±0.10)rad/mm比(4.33±0.20)rad/mm,P=0.004]增加,平均血管分支长度略缩短但差异无统计学意义(P>0.05)。结论基于Micro-CT的成像展示了肝癌原位移植瘤血管的三维结构,通过量化肝癌和健康肝脏的血管特征差异,可以进一步明确抑制肿瘤血液供应的潜在途径。

From histology to micro-CT:Measuring and modeling resorption cavities and their relation to bone competence

The process of bone remodelling plays an essential role in the emergence and maintenance of bone geometry and its internal structure.Osteoclasts are one of the three main bone cell types that play a crucial role in the bone remodelling cycle.At the microstructural level,osteoclasts create bone deficits by eroding resorption cavities.Understanding how these cavities impair the mechanical quality of the bone is not only relevant in quantifying the impact of resorption cavities in healthy bone and normal aging,but maybe even more so in quantifying their role in metabolic bone diseases.Meta-bolic bone diseases and their treatment are both known to affect the bone remodelling cycle;hence,the bone mechanical competence can and will be affected.How-ever,the current knowledge of the precise dimensions of these cavities and their effect on bone competence is rather limited.This is not surprising considering the difficulties in deriving three-dimensional(3D)properties from two-dimensional(2D)histological sections.The measurement difficulties are reflected in the evalua-tion of how resorption cavities affect bone competence.Although detailed 3D models are generally being used to quantify the mechanical impact of the cavities,the representation of the cavities themselves has basicallybeen limited to simplified shapes and averaged cavityproperties.Qualitatively,these models indicate that cav-ity size and location are important,and that the effectof cavities is larger than can be expected from simplebone loss.In summary,the dimensions of osteoclastresorption cavities were until recently estimated from2D measures;hence,a careful interpretation of resorp-tion cavity dimensions is necessary.More effort needsto go into correctly quantifying resorption cavities usingmodern 3D imaging techniques like micro-computedtomography(micro-CT)and synchrotron radiation CT.Osteoclast resorption cavities affect bone competence.The structure-function relationships have been ana-lysed using computational models that,on one hand,provide rather detailed information on trabecular bonestructure,but on the other incorporate rather crudeassumptions on cavity dimensions.The use of high-resolution representations and parametric descriptionscould be potential routes to improve the quantitativefidelity of these models.

PET/CT联合血清lncRNA THRIL、miR-98-5p检测对孤立性肺结节良恶性的诊断价值

目的 探究正电子发射断层扫描和计算机断层扫描(PET/CT)联合血清长链非编码RNA THRIL(lncRNA THRIL),微小RNA-98-5p(miR-98-5p)检测对孤立性肺结节(SPN)良恶性的鉴别诊断价值。方法 选取2022年5月至2023年5月在南阳市中心医院收治的115例SPN患者作为研究对象,根据病理检查结果将SPN患者分为良性组(75例)和恶性组(40例),比较两组血清lncRNA THRIL、miR-98-5p表达水平。Pearson法分析血清lncRNA THRIL与miR-98-5p的相关性。一致性Kappa检验比较PET/CT、血清lncRNA THRIL、miR-98-5p单独及联合诊断SPN恶性与病理结果的一致性。受试者工作特征(ROC)曲线分析PET/CT检查联合血清lncRNA THRIL、miR-98-5p水平对恶性SPN的诊断价值。结果 恶性组血清lncRNA THRIL水平比良性组高,miR-98-5p水平比良性组低(P<0.05)。Pearson分析显示,lncRNA THRIL与miR-98-5p表达呈负相关(r=-0.491,P<0.05),且lncRNA THRIL与miR-98-5p有靶向结合位点。PET/CT、血清lncRNA THRIL、miR-98-5p联合共诊断出38例恶性SPN患者,与病理诊断的一致性较高,Kappa值为0.729(P<0.05),联合诊断恶性SPN的特异度、灵敏度、阳性预测值、阴性预测值、准确性均最高,分别为90.67%、95.00%、84.44%、97.14%、92.17%。PET/CT、血清lncRNA THRIL、miR-98-5p联合诊断恶性SPN的曲线下面积(AUC)为0.921(95%CI:0.874~0.968),均优于各自单独检测(Z=2.235、2.478、2.444,P<0.05)。结论 PET/CT联合血清lncRNA THRIL、miR-98-5p检测可提高对恶性SPN诊断的灵敏度及准确性,对SPN良恶性的鉴别诊断具有一定的应用价值。