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Noise reduction in MR angiography with nonlinear anisotropic filtering
Author(s) -
Du Jiang,
Fain Sean B.,
Gu Tianliang,
Grist Thomas M.,
Mistretta Charles A.
Publication year - 2004
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.20047
Subject(s) - spatial filter , anisotropy , isotropy , image resolution , filter (signal processing) , nonlinear system , spatial frequency , contrast to noise ratio , noise (video) , projection (relational algebra) , physics , optics , computer science , image quality , artificial intelligence , algorithm , computer vision , image (mathematics) , quantum mechanics
Purpose To evaluate three‐dimensional nonlinear anisotropic filtering in suppressing image noise in high spatial resolution magnetic resonance angiograms (MRA) acquired with hybrid undersampled projection reconstruction and phase contrast vastly undersampled isotropic projection reconstruction (PC‐VIPR). Materials and Methods Three‐dimensional nonlinear anisotropic filtering was quantitatively analyzed and evaluated through the measurement of contrast to noise ratio (CNR) in PC‐VIPR images and contrast enhanced peripheral MRA images. To filter MRA images with ultra‐high spatial resolution and poor CNR, a spatial frequency dependent nonlinear anisotropic filtering algorithm was proposed that uses two‐step processing to filter the whole spatial frequency data. Results Three‐dimensional nonlinear anisotropic filtering was shown to be effective in suppressing noise and improving CNR in MRA with isotropic spatial resolution. Higher CNR was achieved using spatial frequency dependent nonlinear anisotropic filtering. A typical CNR gain of between 50–100% was shown in our studies. Conclusion Three‐dimensional nonlinear anisotropic filtering significantly improved CNR in MRA images with isotropic spatial resolution. Spatial frequency dependent nonlinear anisotropic filtering further improved CNR for MRA images with ultra‐high spatial resolution and low CNR. J. Magn. Reson. Imaging 2004;19:632–639. © 2004 Wiley‐Liss, Inc.