Laboratory of Experimental Medicine and Endocrinology, K.U.Leuven, Leuven, Belgium.
Bone. 2011 Oct;49(4):613-22. doi: 10.1016/j.bone.2011.06.031. Epub 2011 Jul 4.
In vivo micro-computed tomography (micro-CT) will offer unique information on the time-related changes in bone mass and structure of living mice, provided that radiation-induced side effects are prevented. Lowering the radiation dose, however, inevitably decreases the image quality. In this study we developed and validated a protocol for in vivo micro-CT imaging of mouse bone architecture that retains high quality images but avoids radiation-induced side effects on bone structure and hematological parameters. The left hindlimb of male C57Bl/6 mice was scanned in vivo at 3 consecutive time points, separated each time by a 2-week interval. Two protocols for in vivo micro-CT imaging were evaluated, with pixel sizes of 9 and 18 μm and administered radiation doses of 434 mGy and 166 mGy per scan, respectively. These radiation doses were found not to influence trabecular or cortical bone architecture in pre-pubertal or adult mice. In addition, there was no evidence for hematological side effects as peripheral blood cell counts and the colony-forming capacity of hematopoietic progenitor cells from bone marrow and spleen were not altered. Although the images obtained with these in vivo micro-CT protocols were more blurred than those obtained with high resolution (5 μm) ex vivo CT imaging, longitudinal follow-up of trabecular bone architecture in an orchidectomy model proved to be feasible using the 9 μm pixel size protocol in combination with a suitable bone segmentation technique (i.e. local thresholding). The image quality of the 18 μm pixel size protocol was too degraded for accurate bone segmentation and the use of this protocol is therefore restricted to monitor marked changes in bone structure such as bone metastatic lesions or fracture healing. In conclusion, we developed two micro-CT protocols which are appropriate for detailed as well as global longitudinal studies of mouse bone architecture and lack noticeable radiation-induced side effects.
体内 micro-CT（micro-CT）将提供有关活鼠骨量和结构随时间变化的独特信息，前提是要防止辐射引起的副作用。然而，降低辐射剂量不可避免地会降低图像质量。在这项研究中，我们开发并验证了一种用于活体小鼠骨结构 micro-CT 成像的方案，该方案保留了高质量的图像，但避免了辐射对骨结构和血液学参数的副作用。雄性 C57Bl/6 小鼠的左后肢在 3 个连续时间点进行了体内扫描，每次间隔 2 周。评估了两种体内 micro-CT 成像方案，像素大小分别为 9μm 和 18μm，每次扫描的辐射剂量分别为 434mGy 和 166mGy。这些辐射剂量不会影响未成年或成年小鼠的小梁或皮质骨结构。此外，没有证据表明血液学方面有副作用，因为外周血细胞计数和骨髓和脾脏造血祖细胞的集落形成能力没有改变。尽管这些体内 micro-CT 方案获得的图像比高分辨率（5μm）体外 CT 成像获得的图像更模糊，但使用 9μm 像素大小方案结合合适的骨分割技术（即局部阈值），对去势模型中小梁骨结构的纵向随访是可行的。18μm 像素大小方案的图像质量太差，无法进行准确的骨分割，因此该方案仅限于监测骨结构的明显变化，如骨转移病灶或骨折愈合。总之，我们开发了两种 micro-CT 方案，适用于详细和全面的小鼠骨结构纵向研究，并且缺乏明显的辐射诱导的副作用。
