The power spectral density as a texture measure in computed tomographic scans of the liver
Andrew John Coleman, K. Tonge, Samantha Rankin · British Journal of Radiology · 1982
Several studies on computed tomographic (CT) scans of the liver have confirmed that there is no significant difference in the EMI number (EU) of normal and cirrhotic livers (Stephens et al, 1977; Levitt et al, 1977). This result has led to the investigation of more sophisticated techniques for identifying cirrhosis of the liver from CT scans. The possibility that liver tissue could be characterized by a texture or pattern measure has been investigated (Pullan et al, 1978; Ritchings et al, 1979) with some success using the auto-correlation function. It was decided to follow up this work using the power spectral density (PSD) as a measure to analyse the texture in selected regions of CT scans of the liver. Using this measure, a region of coarse texture has its PSD concentrated at low spatial frequencies and a region of fine texture has its PSD concentrated at high spatial frequencies, since the degree of textural coarseness is proportional to the spatial period. Similar Fourier domain techniques have been used successfully to classify textures on chest X-rays (Sutton & Hall, 1972; Kruger et al, 1974) and can be readily implemented on a computer due to the digital nature of CT data.