title: Quantitative scanning acoustic microscopy compared to microradiography for assessment of new bone formation.
abstract: Recently, it has been shown that quantitative scanning acoustic microscopy (SAM) is a powerful tool to image the acoustic impedance of even inhomogeneous materials like bone. Therefore, the aim of our study was to compare SAM to conventional microradiography with respect to histomorphometrical assessment of undecalcified sections of newly formed bone. Forty specimens were harvested 12 weeks after implantation of either autogenous cancellous bone graft or 5.0 mg of Osteogenic Protein-1 (BMP-7) in a critical-sized defect model in sheep. Undecalcified transverse bone sections of 500 microm thickness were investigated with conventional microradiography and SAM. Linear regression analysis was carried out to compare the measurements of the area of new bone formation within the defect sites. Both methods allowed for good discrimination between newly formed bone and cortical bone at the edges of the former defect. Images obtained with SAM revealed a better resolution and sharpness compared to that of microradiographs since SAM imaging unlike microradiography does not depend on the thickness of bone sections. The results of quantitative histomorphometric analysis obtained by both methods showed no significant differences, and it was possible to predict 90% of the variability of each method (coefficient of determination r2 = 0.90; P < 0.0001). In conclusion, SAM offers comparable quantitative histomorphometric information with a better spatial resolution than conventional microradiography. Thus, SAM is a promising new micro-visualizing technique for basic bone research.
authors.affiliation: Experimental Surgery and Regenerative Medicine, Department of Surgery, University of Munich (LMU), Nussbaumstrasse 20, D-80336 München, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Regauer
authors.forename: Philipp
authors.initials: P
authors.lastname: Jürgens
authors.forename: Ursula
authors.initials: U
authors.lastname: Budenhofer
authors.forename: Martina
authors.initials: M
authors.lastname: Hartstock
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Böcker
authors.forename: Dominik
authors.initials: D
authors.lastname: Bürklein
authors.forename: Wolf
authors.initials: W
authors.lastname: Mutschler
authors.forename: Robert
authors.initials: R
authors.lastname: Sader
authors.forename: Matthias
authors.initials: M
authors.lastname: Schieker
mesh_terms: D000818:Animals; D001846:Bone Development; D008853:Microscopy / Q000379:methods*; D011859:Radiography / Q000379:methods*; D012756:Sheep