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Automated quantification of ultrasonic fatty liver texture based on curvelet transform and SVD

Bharath R., Mishra P. K., Rajalakshmi P.

Biocybernetics and Biomedical Engineering

2018

Vol. 38, no. 1

145--157

Fatty liver is a prevalent disease and is the major cause for the dysfunction of the liver. If fatty liver is untreated, it may progress into chronic diseases like cirrhosis, hepatocellular carcinoma, liver cancer, etc. Early and accurate detection of fatty liver is crucial to prevent the fatty liver progressing into chronic diseases. Based on the severity of fat, the liver is categorized into four classes, namely Normal, Grade I, Grade II and Grade III respectively. Ultrasound scanning is the widely used imaging modality for diagnosing the fatty liver. The ultrasonic texture of liver parenchyma is specific to the severity of fat present in the liver and hence we formulated the quantification of fatty liver as a texture discrimination problem. In this paper, we propose a novel algorithm to discriminate the texture of fatty liver based on curvelet transform and SVD. Initially, the texture image is decomposed into sub-band images with curvelet transform enhancing gradients and curves in the texture, then an absolute mean of the singular values are extracted from each curvelet decomposed image, and used it as a feature representation for the texture. Finally, a cubic SVM classifier is used to classify the texture based on the extracted features. Tested on a database of 1000 image textures with 250 image textures belonging to each class, the proposed algorithm gave an accuracy of 96.9% in classifying the four grades of fat in the liver.

Kinetic description of microwave Raman regime free-electron laser in the presence of helical wiggler and guiding magnetic fields

Mishra P. K.

Optica Applicata

2007

Vol. 37, nr 1-2

195-204

A full dispersion relation obtained for free-electron laser by kinetic approach based on the method of characteristics in the presence of circularly polarized, periodic, static helical wiggler magnetic field and guide magnetic field incorporating the detailed relativistic particle trajectories is reduced to Raman regime approximations. The temporal and spatial growth rates are evaluated in microwave region. A detailed analysis has been done for temporal and spatial growth rates in Raman regime, especially for microwave region. The spatial growth rate is more than that of temporal growth. The results have been compared with available results obtained by other techniques.