The rician distribution of noisy mri data


  • HáKon Gudbjartsson,

    Corresponding author
    1. Massachusetts Institute of Technology Department of EECS (H.G.), and Harvard Medical School
    • Hákon Gudbjartsson, Department of Radiology/BWH, 221 Longwood Avenue, Boston, MA 02115
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  • Samuel Patz

    1. Brigham and Women's Hospital (S.P.), Department of Radiology, Boston, Massachusetts.
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The image intensity in magnetic resonance magnitude images in the presence of noise is shown to be governed by a Rician distribution. Low signal intensities (SNR < 2) are therefore biased due to the noise. it is shown how the underlying noise can be estimated from the images and a simple correction scheme is provided to reduce the bias. the noise characteristics in phase images are also studied and shown to be very different from those of the magnitude images. Common to both, however, is that the noise distributions are nearly Gaussian for SNR larger than two.