Application of the discrete torus wavelet transform to the denoising of magnetic resonance images of uterine and ovarian masses

A new numerical wavelet transform, the discrete torus wavelet transform, is described and an application is given to the denoising of abdominal magnetic resonance imaging (MRI) data. The discrete tori wavelet transformis an undecimated wavelet transformwhich is computed using a discrete Fourier transformand multiplication instead of by direct convolution in the image domain. This approach leads to a decomposition of the image onto frames in the space of square summable functions on the discrete torus, l2(T2). The new transformwas compared to the traditional decimated wavelet transformin its ability to denoise MRI data. By using denoised images as the basis for the computation of a nuclear magnetic resonance spin-spin relaxation-time map through least squares curve fitting, an error map was generated that was used to assess the performance of the denoising algorithms. The discrete torus wavelet transformoutperformed the traditional wavelet transformin 88% of the T2 error map denoising tests with phantoms and gynecologic MRI images.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.