1. A method for processing a computed tomography image comprising the steps of: obtaining a computed tomography image of a lung of a subject with contrast agent administered to the subject so as to affect said image, said image being comprised of pixels respectively having gray scale values associated therewith; determining pixels representing pulmonary parenchyma in said image, as pulmonary parenchyma pixels; and generating a processed image by presenting said pulmonary parenchyma pixels in false colors and presenting remaining pixels in said image in said gray scale values.