Investigation of spatio-temporal tissue changes in an osteoporotic rat model related to activity and hormone replacement therapy with in vivo micro computed tomography using 4D-imaging

• Applicant: Dr.-Ing. Ricardo Bernhardt
• Subject Area: Medical Physics, Biomedical Technology
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 258678824

Osteoporosis is described as a pathological change of the balance between composition and decomposition of bone, which lead to a gradual lose of bone quality up to an increased susceptibility for fractures. An early diagnosis of an osteoporotic disease is difficult, as the bone tissue changes start without indications and will usually be found during a present fracture. Individual and cross-linked aspects like bone loading and a precautionary hormone replacement therapy for women may influence the origin and the progress of the osteoporosis. The analytical techniques to investigate the individual progress of tissue changes under the described aspects in man are limited.With in vivo micro-computed tomography (in vivo µCT) mineralised bone tissue can be visualised with high spatial resolution using moderate irradiation times. Aim of the project is the investigation of tibia bone changes with the surrounding tissue in an osteoporotic rat model with time-lapse in vivo µCT. The visualisation and analysis of small bone changes will be realised with the overlay of sequential 3D images. The time dependant changes within this animal model will be relate to age, individual movement and hormone therapy of the animals. To monitor the movement of the animals during cage housing a new experimental set-up will be investigated. Therefore wireless miniature pedometers will be fixed on the animals for real-time measurement of their movement. Rotation controlled bogie wheels will be placed in the cages of selected animal groups to study the influence of a movement stimulation.The condition of the surrounded soft tissue and the vascularisation of the tibia could also be related to the development of osteoporosis. Therefore the three-dimensional angiogenesis of the tibia will be analysed during the in vivo µCT with the use of contrast agents. For tissue explants contrast agents, which improve the soft tissue visualisation for µCT, will be tested and analysed. Also related to the contrast enhancement of lower absorbing tissue within reconstructed µCT images different sinogramm filter algorithms will be investigated with the aim of an overall improvement of the signal-to-noise ratio for soft tissue values.

• DFG Programme: Research Grants