Bone Densitometric Analysis using Cone Beam Computed Tomography (Cone Beam CT) and Computed Tomography (CT): Establishing the Correlation between Predicted and Actual Values

Background:One of the major drawbacks of cone beam computed tomography (cone beam CT) is that unlike CT, the gray density values obtained from cone beam CT are relative, and not absolute as obtained in the case of CT. The present study was conducted with the intent to perform a comparative bone densitometric analysis using cone beam CT and CT and to determine if there was a mathematical correlation between the two. Materials and Methods:The present in-vitro study included CT and cone beam CT scans of 30 dry mandibles wherein the gray density values from well-demarcated, precise anatomical areas were obtained, analyzed, and compared. Also, the dependent t-test and Pearson's correlation coefficient test were used for statistical analysis, while probability values (P values) < 0.05 were contemplated as being statistically significant. Results:Pearson's correlation between the gray density values for different combinations of point(s)/group(s) as derived on CT and cone beam CT images revealed the results to be statistically significant for each of the imaging methods used, individually and when compared in between the two methods, in all the cases (P < 0.001) when analyzed at 5% level of significance. Conclusions:The mean gray density values obtained with cone beam CT were found to be significantly higher than the ones derived from CT in the present study, though, a linear correlation was observed between the values obtained from cone beam CT and CT, which can be used to convert the relative values obtained with cone beam CT into absolute values derived with CT.