Micro-computed tomography, also known as Micro-CT, is the preclinical analogue of clinical CT, providing higher spatial resolution (voxel size <= 100 microns) for imaging small animal models of disease. The growing interest in small animal models and the development of new X-ray detectors stimulated considerable development of dedicated small animal scanners in the 1990s. Now, Micro-CT systems have become highly sophisticated and are an essential part of preclinical imaging centers in both academia and industry. Conventionally, the samples can be analyzed almost without any sample preparation process generally in a non-destructive way [1]. Biocytogen present a series of applications for both in vivo and ex vivo imaging.
Schematic illustration showing the basics of Micro-CT.[2]
FVB老龄鼠自发肺癌抗体药物药效评价。 (a) FVB老年鼠自发肺癌结节示意图,分别展示了横断面、冠状面、矢状面以及三种不同渲染方式的3D重建图像(绿色:肺部,红色:骨骼,蓝色:肿瘤,来自软件“simpleware”,蓝色肺部和红色肿瘤)。(b,c) 单臂试验下,靶向药物治疗后结节抓取绘制3D重建图像,其体积的变化量统计图。(n=每组10/8)
Micro-CT检测肝肿瘤。(a)肝原位异种移植模型肿瘤示意图,黄色线段及方框内标注信息为实体瘤测量线段及长度,下方为3D渲染图像可在相同位置看到非肝细胞的肿瘤实质区域。(b)STAM模型肿瘤示意图黄色线段及方框内标注信息为实体瘤测量线段及长度,下方为3D渲染图像可在相同位置看到非肝细胞的肿瘤实质区域。(c,d) 肝原位肿瘤体积与STAM模型肿瘤最大长经统计图。
脂肪分割示意图和肥胖小鼠及野生小鼠脂肪3D重建。(a) 红色为内脏脂肪,蓝色为皮下脂肪。重建图显示肥胖小鼠内脏及皮下大量脂肪,野生小鼠几乎无明显脂肪堆积(b)脂肪/体重、皮下脂肪/体重、内脏脂肪/体重质量比,HFD组(G1),STD组(G4)。
使用Micro-CT量化脂肪肝。图片由上至下从左至右展示,肥胖小鼠肝脏感兴趣区域的抓取,模块自动进行分析,CT值比反应脂肪肝程度以及肝脏绝对CT值的比较。
卵巢切除诱导的骨质疏松模型离体检测。(a)骨质疏松模型假手术组(sham)和手术组(OVX)3D重建图像。(b)股骨松质骨和皮质骨面积。(c)骨小梁、皮质骨结构性参数以及密度属性参数统计图。指标意义参考下方表格,综上结果模型特征明显,手术成功。
活体下,测定骨密度支持自定义区域以及长度,如红色区域股骨远端,紫色区域股骨近端及脊椎骨等。Rod1、Rod2、Rod3、Rod4分别为不同密度的羟基磷灰石。
靶向抗体药物治疗药效良好。假手术组(G3),手术组(G4),药物溶剂组(G5),药物浓度递增组(G6-G8),数据显示为平均值±SEM,并使用单因素ANOVA进行分析与G4进行比较,“in vivo BMD”与G5进行比较。
博来霉素诱导的小鼠肺纤维化模型。根据不同HU区间进行正常、低通气、不通气区域体积的分割。在第4周,结果显示低通气和不通气区域的比例都很高,然后在第10周和第16周之间明显减少,而在正常通气的区域,则呈现相反的态势。[3]
小鼠交叉韧带横断术(ACLT)骨性关节炎。a. 骨性关节炎模型3D重建图,手术组软骨下骨大面积增生、磨损。b. 内侧半月板抓取示意图 c. 股骨软骨下骨松质骨横截面,手术组骨体积减少。d. 软骨下松骨结构性参数以及胫骨平面各项参数。
三维成像显示不正常表型小鼠长骨(四肢)可见多处骨裂和骨增厚以及弯曲。颅骨、髋骨、坐骨可见明显异常。
Conclusion
As a non-destructive and high-resolution imaging technique, Micro-CT can be used complimentarily with other imaging techniques in an attempt to integrate the visual results of the different methods and, thus, reach more solid scientific conclusions. The intrinsic physical limitations of each imaging technique have led to more comprehensive approaches by the combination of several techniques, compiling a broader range of information from cell and tissue-level histomorphology to three-dimensional structures [4].
[1] Clark D P , Badea C T . Advances in Micro-CT imaging of small animals[J]. Physica Medica, 2021, 88(6):175-192.
[2] Cengiz I F , Oliveira J M , Reis R L . Micro-CT -a digital 3d microstructural voyage into scaffolds: a systematic review of the reported methods and results[J]. 2019.
[3] Song Shengren,Fu Zhenli,Guan Ruijuan et al. Intracellular hydroxyproline imprinting following resolution of bleomycin-induced pulmonary fibrosis.[J] .Eur Respir J, 2022, 59.
[4] Keklikoglou K , Arvanitidis C , Chatzigeorgiou G , et al. Micro-CT for Biological and Biomedical Studies: A Comparison of Imaging Techniques.[J]. Journal of imaging, 2021, 7(9).