Micro-CT: Technology and applications for assessing bone structure

The strength and fracture resistance of bone is determined by the structure of the trabecular network and the cortical shell. While standard 2D techni ques like histomorphometry are inadequate to assess the 3D nature of the tr abecular network, isotropic 3D datasets of this network can be acquired wit h the new imaging modality of mu CT. However, so far the quantitative analy sis of the generated datasets, in particular the extraction of appropriate parameters describing the bone structure, has not been finally solved. In t his article we describe the technology and applications of mu CT systems re levant in the field of osteology. The most im portant technical features of current mu CT systems in this context are: 1. A spatial resolution down to 5-10 mu m can be achieved. 2. The maximum sample size is related to the de sired resolution by a factor of approximately 1000, that is, a resolution o f 10 mu m limits the maximum sample size to approximately 1 cm. 3. Scan tim es for mu CT systems vary between minutes and hours. Currently five areas for the application of mu CT systems in osteology can be identified:1. The search of parameters characterizing the 3D trabecular structure. 2. The application of finite element models to determine the bio chemical competence of the structural parameters. 3.The use of mu CT in pre clinical trials to study drug effects in small animals.4. The validation of analysis methods used in high-resolution in-vivo imaging systems. 5. The 3 D quantification of modeling and remodeling processes.