Motivated by statistical thermodynamics, we develop a technique using stochastic resonance-based tomographic transform for enhancement of noisy or indistinct computer-assisted tomographic images of the brain lesions for radiological diagnosis. The proposed method makes the edges of the lesion prominent, delineates the edematous zones more clearly, enhances the active zone in tumors, and clarifies the latent structure of the lesions, the mean enhancement index being 165%. The advantages of this method are that it can simultaneously operate both as an enhancement process and as a noise-reduction operation, and that the method can also optimally enhance an image even if the noise level is considerable. A general approach of thermodynamics-based image enhancement for computed tomographic diagnosis is outlined.