Premium
Noise reduction in three‐dimensional phase‐contrast MR velocity measurementsl
Author(s) -
Song Samuel M.,
Napel Sandy,
Glover Gary H.,
Pelc Norbert J.
Publication year - 1993
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.1880030407
Subject(s) - divergence (linguistics) , noise reduction , noise (video) , projection (relational algebra) , reduction (mathematics) , contrast (vision) , physics , phase (matter) , signal to noise ratio (imaging) , optics , mathematics , nuclear magnetic resonance , acoustics , computer science , geometry , algorithm , computer vision , image (mathematics) , philosophy , linguistics , quantum mechanics
The authors have developed a method to reduce noise in three‐dimensional (3D) phase‐contrast magnetic resonance (MR) velocity measurements by exploiting the property that blood is incompressible and, therefore, the velocity field describing its flow must be divergence‐free. The divergence‐free condition is incorporated by a projection operation in Hilbert space. The velocity field obtained with 3D phase‐contrast MR imaging is projected onto the space of divergence‐free velocity fields. The reduction of noise is achieved because the projection operation eliminates the noise component that is not divergence‐free. Signal‐to‐noise ratio (S/N) gains on the order of 15%‐25% were observed. The immediate effect of this noise reduction manifests itself in higher‐quality phase‐contrast MR angiograms. Alternatively, the S/N gain can be traded for a reduction in imaging time and/or improved spatial resolution.