Objectives: The goal of this study was to examine the feasibility of in vivo imaging of trabecular bone around titanium implants by means of microfocus computed tomography (micro-CT) and the use of rabbits for this purpose.
Materials and Methods: Ten male rabbits type Hollander, received a titanium implant (1.7 mm diameter and 10 mm length) in the trabecular bone of the left tibia. Seven weeks later a micro-CT scan was taken. Four rabbits were used to monitor potential harmful effects from X-ray absorption until 4 weeks after scanning. A second group of six rabbits was used for testing the hypothesis that a good correlation exists between in vivo micro-CT images and histological images of trabecular bone around titanium implants. The six rabbits were scanned and sacrificed immediately. The tibias were extracted and submitted to standard histological procedures. This resulted in a total of 12 histological sections and their corresponding 12 micro-CT images. Bone area measurements were performed at the left and right side of the implant in three regions: 0-500, 500-1000 and 1000-1500 mu m distance from the implant interface. Intra-class correlations (ICC) were calculated between both techniques.
Results: The four rabbits did not show any sign of radiodermatitis 4 weeks after scanning. In the micro-CT images of the group of six rabbits, trabeculae are visible, but not well defined, due to the presence of noise in the image. The ICC for the right implant side were 0.44 for zone 0-500 mu m, 0.48 for zone 500-1000 mu m and 0.40 for zone 1000-1500 mu m. The ICC for the left implant side could not be calculated.
Conclusion: A low agreement was found between the bone measurements from histology and in vivo micro-CT images. The use of the in vivo micro-CT for trabecular bone imaging around metallic implants should be restricted to track tendencies in follow-up studies.