Assessment of texture and preferred orientation of trabecular bone of human, dry, cadaveric vertebral slices.

Abstract

This paper reports an assessment of texture and preferred orientation of trabeculae in tomographic like images acquired from 1.5 mm thick midsagital slices taken from dry, cadaveric, human vertebrae with wedging lower than 8 degrees (sexagesimal). Slices were scanned and the digital images obtained assesed with the Autocorrelation Function (ACF, computed from the Fast Fourier Transform [FFT]). Trabecular thickness and average of medullar spaces areas per unit area were measured on the images. Finally, the slices were submitted to physical analysis (bone tissue volume, ash content). Decay of vertebral trabecular bone was assessed with Vmin/Vmax (ACF ellipticity, a parameter that ranges from aproximately 1,0 when the integrities of vertical and horizontal trabeculae are conserved to 0.3 when the loss of bone mass has ocurred mainly at the expense of horizontal trabeculae). Vmin/Vmax was significantly correlated with the fraction of vertebral volume occupied by bone tissue (BVS/TVS). The latter showed a significant and positive correlation with the vertebral ash density. Average trabecular thickness correlated with the BVS/TVS ratio and the average area of medullar spaces is inversely related with their number per unit area. The data support the hypothesis that the parameter Vmin/Vmax, obtained through the autocorrelation function computed from the FFT of 2D images, can be a surrogate of three dimensional assessment of the integrity of vertebral orthogonal trabecular lattice. Clinical application of this analysis must await the development of imaging techniques capable to examine the trabecular structure at high resolution with radiation levels compatible with clinical use.