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The magic angle effect: A source of artifact, determinant of image contrast, and technique for imaging
Author(s) -
Bydder Mark,
Rahal Andres,
Fullerton Gary D.,
Bydder Graeme M.
Publication year - 2007
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.20850
Subject(s) - magic angle , magic (telescope) , orientation (vector space) , physics , materials science , optics , nuclear magnetic resonance , biomedical engineering , geometry , mathematics , medicine , quantum mechanics , nuclear magnetic resonance spectroscopy
This review provides a formalism for understanding magic angle effects in clinical studies. It involves consideration of the fiber‐to‐field angle for linear structures such as tendons, ligaments, and peripheral nerves, disc‐like and circular structures such as menisci and labra, as well as complex three‐dimensional structures. There may be one or more fiber types with different orientations within each of these tissues. The orientation of these fibers to B 0 is crucial in determining their magic angle effect. Tissues may show a variety of appearances depending on their baseline T2, as well as the increase in T2 produced by the magic angle effect. The appearances are affected by TE, which affects both the general tissue signal level and the change in signal produced by the magic angle effect, fiber‐to‐slice orientation, and partial volume effects. Deliberate positioning of structures and tissues at particular orientations to B 0 can be used to increase the signal from tissues such as tendons and ligaments and so allow them to be imaged with conventional sequences. The technique can also be used to produce contrast between tissues with fibers that have different orientations to B 0 . J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.