Micoradiography and backscattered electron (BSE) imaging are techniques used to investigate the morphologic, histometric, and mineral content changes at the bone/biomaterials interface. Investigators have shown that the superimposition of multiple tissue layers can cause errors with both the morphologic observations and the histometric measurements of bone. The objective of this study was to document errors in the bone mineral content measurements associated with overlapping tissues.
Using a digital image analysis system, microradiographic and BSE images from canine cortical and cancellous bone were captured and analyzed. The results of this study showed that microradiography had more projection effect errors associated with the morphology and histometry. The BSE technique provided substantially better resolution of the bone morphology and showed significantly more (p$0.05) bone surface perimeter than the microradiographic technique. Contrary to the literature, the BSE images did not show less bone area than the microradiographic images of the identical regions. This discrepancy was explained by projection effect errors and over penetration artifacts of the X-ray beam.
Unique to this study was the documentation that microradiography has inherent projection effect errors associated with mineral content measurements. The SSE images had significantly more (p$0.05) graylevels present than the microradiographic images. Due to the limited tissue overlap, the BSE images provide excellent morphologic resolution, accurate bone histometry and the ability to accurately measure the mineral content of cortical and cancellous bone at a microscopic level.
Bachus, K. N. and Bloebaum, R. D.
"Projection Effect Errors in Biomaterials and Bone Research,"
Cells and Materials: Vol. 2
, Article 8.
Available at: http://digitalcommons.usu.edu/cellsandmaterials/vol2/iss4/8