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Sources of distortion in functional MRI data

✍ Scribed by Peter Jezzard; Stuart Clare

Publisher
John Wiley and Sons
Year
1999
Tongue
English
Weight
313 KB
Volume
8
Category
Article
ISSN
1065-9471

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✦ Synopsis

Functional magnetic resonance image (fMRI) experiments rely on the ability to detect subtle signal changes in magnetic resonance image time series. Any areas of signal change that correlate with the neurological stimulus can then be identified and compared with a corresponding high-resolution anatomical scan. This report reviews some of the several artefacts that are frequently present in fMRI data, degrading their quality and hence their interpretation. In particular, the effects of magnetic field inhomogeneities are described, both on echo planar imaging (EPI) data and on spiral imaging data. The modulation of these distortions as the subject moves in the magnet is described. The effects of gradient coil nonlinearities and EPI ghost correction schemes are also discussed.

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