Hello,
Is the effectiveness of field correction for compensating for B0
distortions at least partially dependent on the phase encoding direction
used to acquire the BOLD or DTI data that is to be corrected?
To use Siemen's parameter lingo, a "P>>A" phase encoding direction
stretches signal from frontal cortex outward (anteriorly, into empty
space), whereas "A>>P" (which is unfortunately Siemen's default)
compresses signal from frontal cortex (i.e., moves frontal signal
posteriorly, onto existing brain). It seems that once signal from
multiple voxels is compressed into 1 voxel that not much correction
would be possible... Is that indeed the case?
thanks,
-MH
--
Michael Harms, Ph.D.
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Conte Center for the Neuroscience of Mental Disorders
Washington University School of Medicine
Department of Psychiatry, Box 8134
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660 South Euclid Ave. Fax: 314-747-2182
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