Investigation of using bone texture analysis on bone densitometry images

We previously developed bone texture analysis methods to assess bone strength on digitized radiographs. Here, we compare the analyses performed on digitized screen-film to those obtained on peripheral bone densitometry images. A leg phantom was imaged with both a PIXI (GE Medical Systems; Milwaukee, WI) bone densitometer (0.200-mm pixel size) and a screen-film system, with the films being subsequently digitized by a laser film digitizer (0.100-mm pixel size). The phantom was radiographically scanned multiple times with the densitometer at the default parameters and for increasing exposure times. Fourier-based texture features were calculated from regions of interest from images from both modalities. The bone densitometry images contained more quantum noise than the radiographs resulting in increased values for the first moment of the power spectrum texture feature (1.22 times higher than from the standard radiograph). Presence of such noise may adversely affect the texture feature's ability to distinguish between strong and weak bone. By either increasing the exposure time or averaging multiple scans in the spatial frequency domain, we showed a reduction in the effect of the quantum mottle on the first moment of the power spectrum.