A comparison of the texture of computed tomography and projection radiography images of vertebral trabecular bone using fractal signature and lacunarity

The structural integrity of trabecular bone is an important factor characte rizing the biomechanical strength of the vertebra, and is determined by the connectivity of the bone network and the trabeculation pattern. These can be assessed using texture measures such as the fractal signature, and lacun arity from a high resolution projection radiograph. Using central sections of lumbar vertebrae we compared the results obtained from high-resolution t ransverse projection images with those obtained from spatially registered l ow-resolution images from a conventional clinical CT scanner to determine w hether clinical CT data can provide useful structural information. Provided the power spectra of the CT images are corrected for image system blurring , the resulting fractal signature is similar for both modalities. Although the CT images are blurred relative to the projection images, with a consequ ent reduction in lacunarity, the estimated trabecular separation obtained f rom the lacunarity plots is similar for both modalities. This suggests that these texture measures contain essential information on trabecular microar chitecture, which is present even in low resolution CT images. Such quantit ative texture measurements from CT or MRI images are potentially useful in monitoring bone strength and predicting future fracture risk. (C) 2001 IPEM . Published by Elsevier Science Ltd. All rights reserved.