Hi Joshua: Thanks for the input. Very helpful.
Alan On Thu, Apr 24, 2014 at 8:10 PM, Joshua Lee <[email protected]> wrote: > Hi Alan, > > Typically subfields segmentation requires hi-resolution data (e.g. 0.4 x > 0.4 mm in-plane resolution). The thickness of a CA subfield typically range > between 0.5-1.00 mm, but 1.5 T data does not achieve sub-millimeter > resolutions. Further, subfield segmentation typically requires > high-contrast data to discern the internal boundaries formed by the stratum > radiatum/stratum lacunosum-moleculare (SLRM). I doubt that images produced > on a 1.5 T magnet can achieve the necessary contrast. Last, and please > someone correct me if what I say is inaccurate, but doesn't the Van Leemput > method use statistical priors to apply label probabilities in reference to > a generated hippocampal surface? This would imply that the method assigns > label probabilities without reference to a subject's SLRM intensity > information. For volumetry, I am somewhat skeptical that a method that only > relies on a generated surface would be sensitive to group x subfield > interactions; especially double dissociations in which overall volume/shape > of the hippocampus may be similar across groups. That the that was > generated from potentially low resolution, low contrast data cannot help > the matter. Some may disagree about this though and I'd be interested in > hearing what other people think about the matter. In general, I am quite > optimistic about automated methods to segment the subfields. > > Joshua > > > > - > Joshua K. Lee > Doctoral Candidate > Department of Psychology & > Center for Mind and Brain > University of California, Davis > > > > On Thu, Apr 24, 2014 at 12:24 PM, Alan Francis > <[email protected]>wrote: > >> Hi Bruce and FreeSurfers: >> >> I have received a manuscript to review for possible publication. The >> authors have used the subfields algorithm on 1.5T scans and obtained a >> parcellation with values. They have drawn some major conclusions on the >> basis of the findings. My understanding is that this method can only be >> done on 3T. Is the 1.5T results valid? >> >> Please advice. >> >> thanks, >> >> Alan Francis >> >> _______________________________________________ >> Freesurfer mailing list >> [email protected] >> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >> >> >> >> The information in this e-mail is intended only for the person to whom it >> is >> addressed. If you believe this e-mail was sent to you in error and the >> e-mail >> contains patient information, please contact the Partners Compliance >> HelpLine at >> http://www.partners.org/complianceline . If the e-mail was sent to you >> in error >> but does not contain patient information, please contact the sender and >> properly >> dispose of the e-mail. >> >> > > _______________________________________________ > Freesurfer mailing list > [email protected] > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > > > The information in this e-mail is intended only for the person to whom it > is > addressed. If you believe this e-mail was sent to you in error and the > e-mail > contains patient information, please contact the Partners Compliance > HelpLine at > http://www.partners.org/complianceline . If the e-mail was sent to you in > error > but does not contain patient information, please contact the sender and > properly > dispose of the e-mail. > >
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