Anisotropic diffusion filter for enhancement of 23Na imaging of the kidney at 3T - initial results

Linear filters like Gaussian, Fermi or Hanning filter are used in sodium MRI post-processing to increase the signal-to-noise ratio, even though they smooth structures as well as noise and thereby cause a loss of information. To tackle that problem, we propose to use anisotropic diffusion filters (AND) instead. With 2D- and 3D-AND we have been able to increase the SNR by a factor of about 200 to the original image and a factor of 25 to a Gaussian-filtered image on sodium MR images of the human kidneys. The content of the image, i.e. the signal intensities and structures of the imaged objects are maintained. Result images of both, phantom measurements and the MR images of human kidneys show the big advantages of AND over linear filters.