LAUSR

In this paper we present an algorithm for the denoising of small animal positron emission images. The proposed algorithm combines a multiresolution transform with robust filtering of regions. The image is processed in the non-subsampled contourlet domain, taking advantage of the transform ability to capture geometric information of important structures like small lesions and borders between tissues. Additionally, in the transform domain, we proposed to apply quasi‑ robust potentials in order to reduce the noise on regions without borders, this is done by estimating an edge map and a set of image regions. Finally the inverse contourlet transform is applied to obtain a denoised image. Quality tests using the NEMA NU4 2008 phantom show that the proposed method reduces the noise in the image while at the same time the average count is preserved on each region. Comparisons with other methods, using a contrast analysis on a simulated lesion show the superiority of our approach to denoise and preserve small structures such as lesions.