BONE QUALITY SEMINARS: BONE FRACTURE HEALING AND STRENGTHENING Evaluation of bone scaffolds by micro-CT F. Peyrin Published online: 27 April 2011 # International Osteoporosis Foundation and National Osteoporosis Foundation 2011 Abstract This paper reviews the possibilities offered by X-ray micro-CT in bone tissue engineering. This technique provides a fast, nondestructive, and 3D quantification of bone scaffolds, bone ingrowth, and microvascularization. Synchro- tron radiation absorption and phase micro-CT offer additional advantages to image newly formed bone in bioceramic scaffolds and pre-bone matrix. Keywords Bone scaffolds . Microvascularization . Phase contrast . Synchrotron radiation micro-CT . Three dimensional imaging . X-ray micro-CT Introduction Bone tissue engineering is a rapidly evolving domain which requires coordinated progresses in material science and biology. Porous bioceramics that mimic trabecular bone are receiving particular attention for the reparation of diseased bone tissue. The design of scaffolds in terms of composi- tion and geometry as well as that of the cell loading process is the object of many researches to ensure their function- ality in restoring tissue. The optimization of the whole process with many degrees of freedom is a challenging issue. Thus, efficient and rapid methodologies for the quantitative assessment of new bone formation within scaffold are essential. These processes are conventionally assessed ex vivo by histology on microscopic images. However, X-ray micro- CT was first used in the field of bone tissue engineering about a decade ago and the number of research papers employing this technique is exponentially growing. It can be extrapolated that it will become a standard analysis technique in the near future in the same way it has revolutionized the analysis of trabecular bone micro- architecture [1]. In this domain, compared to histomorph- ometry, X-ray micro-CT has shown its efficiency in providing nondestructively and rapidly three-dimensional (3D) images and model-independent measurements on bone microstructure. Concerning bone scaffolds, we shall see that micro-CT is employed to quantify the scaffold geometry, newly formed bone, neovascularization, and pre-bone matrix. Due to the expansion of the domain, the use of micro-CT in bone tissue engineering will be illustrated on selected examples only. In the second section, we review the use of micro-CT and synchrotron radiation (SR) micro-CT for the analysis of bone scaffolds and bone formation. We shall give some technical requirements on the technique and present the advantages of both techniques for the three-dimensional quantification of scaffold and new bone formation. In the third section, we address the issue of analyzing neovascularization which is a major concern in bone tissue engineering. In the fourth section, we discuss the perspectives offered by X-ray phase contrast imaging for the investigation of vascularization and pre-bone matrix formation. F. Peyrin INSERM U1044, CREATIS; CNRS UMR 5220; INSA-Lyon, Villeurbanne, F-69621 Villeurbanne Cedex, France F. Peyrin Université de Lyon, Université Lyon 1 Villeurbanne, F-69622 Lyon, France F. Peyrin (*) ESRF, BP 220, 38043 Grenoble Cedex, France e-mail: peyrin@esrf.fr Osteoporos Int (2011) 22:2043–2048 DOI 10.1007/s00198-011-1609-y