A comparison of micro-CT, microradiography and histomorphometry in bone research

Objective: Intraobserver reliability and agreement were determined for microradiography (MR), micro-computed tomography (mu CT) and histomorphometry (HM). These three modalities were compared for quantitative measurements of bone formation and graft modelling in rat mandibular defects and grafts.

Design: Twelve rats were randomly selected from a larger experiment, evaluating bone formation in rat mandibular defects and bone modelling in grafts. Twelve lateral microradiographs were taken of the grafts. mu CT images were obtained from all defects and grafts (24 specimens). Defects and grafts were cut perpendicularly through their Centre. Microradiographs, mu CT images and histological sections were obtained from the resulting 48 specimens. New bone volume and graft volume were measured using image analysis software on MR and mu CT images. Defect width and graft width were measured using images from HM, MR and mu CT. The results were compared to each other.

Results: The intraobserver reliabilities for the measurements of new bone volume by mu CT, and the measurement of graft modelling by MR and graft volume by mu CT were high. The differences between MR, HM and mu CT were larger in defect width measurements than in graft width measurement. MR measured smaller defects than HM and mu CT. The 95% confidence interval was larger in defect width measurements compared to graft width measurements.

Conclusions: The methods of MR and mu CT image analysis are reliable but preferably should be used in combination as to obtain valid conclusions. HM, MR and mu CT for graft widths measurements showed more agreement than for defect width measurements. MR appears to overestimate bone formation. (C) 2008 Elsevier Ltd. All rights reserved.