A New NSCT Based Contrast Enhancement Algorithm forAmplification of Early Signs of Ischemic Stroke in Brain CT Images

Brain CT images are extensively used in detectionof Cerebrovascular Accidents (CVA). But CT scan is not reallya sensitive test for diagnosis of ischemic stroke. Most of thetimes, early CT images barely show or even don’t show anynoticeable sign of ischemia. But it is possible to put emphasison subtle signs of ischemia by means of image contrastenhancement. Contrast enhancement using multiscaletransforms is one of the most popular approaches in recentyears. Nonsubsampled Contourlet Transform (NSCT) is adirectional multiscale transform that is able to take geometricalstructures into account. In this paper we are about to customizethis transform and improve its performance in contrastenhancement of brain CT images. To this end, we propose a setof simpler and more efficient filters for NonsubsampledPyramid (NSP) and introduce an improved method formodification of directional subbands’ coefficients.

کلیدواژه ها:

Computed Tomography ، stroke ، ischemia ، contrast enhancement ، wavelet ، Contourlet ، NSCT