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Magn Reson Med. 2011 Apr;65(4):1053-61. doi: 10.1002/mrm.22691. Epub 2010 Nov 30.

A novel method for quantifying scanner instability in fMRI.

Author information

  • 1Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, USA. greve@nmr.mgh.harvard.edu

Abstract

A method was developed to quantify the effect of scanner instability on functional MRI data by comparing the instability noise to endogenous noise present when scanning a human. The instability noise was computed from agar phantom data collected with two flip angles, allowing for a separation of the instability from the background noise. This method was used on human data collected at four 3 T scanners, allowing the physiological noise level to be extracted from the data. In a "well-operating" scanner, the instability noise is generally less than 10% of physiological noise in white matter and only about 2% of physiological noise in cortex. This indicates that instability in a well-operating scanner adds very little noise to functional MRI results. This new method allows researchers to make informed decisions about the maximum instability level a scanner can have before it is taken off line for maintenance or rejected from a multisite consortium. This method also provides information about the background noise, which is generally larger in magnitude than the instability noise.

Copyright © 2010 Wiley-Liss, Inc.

PMID:
21413069
[PubMed - indexed for MEDLINE]
PMCID:
PMC3117086
Free PMC Article

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