Thanks for the clarification Eugenio. Would saying that it relies on shape instead of surface be more accurate? I would like to understand better. Also, it is good news that there are plans to model the SLRM. Josh
- Joshua Lee Doctoral Candidate Department of Psychology & Center for Mind and Brain University of California, Davis 530.747.3805 On Mon, Apr 28, 2014 at 12:18 AM, Eugenio Iglesias <e.igles...@bcbl.eu>wrote: > Dear all, > the current module in FreeSurfer works with 1mm T1 data, by relying on > strong shape priors. So, at this point, feeding the algorithm data from a > 3T scanner or a 1.5T scanner is pretty much the same. > Joshua, it is indeed inaccurate to say that the method relies on a > generated hippocampal surface, but you are definitely right regarding the > SLRM: it is not modeled at this point (we have a new version that models it > coming out hopefully soon!). > Cheers, > /Eugenio > > > Juan Eugenio Iglesias > Postdoctoral researcher BCBL > www.jeiglesias.com > www.bcbl.eu > > Legal disclaimer/Aviso legal/Lege-oharra: www.bcbl.eu/legal-disclaimer > > > ----- Original Message ----- > From: "Joshua Lee" <jki...@ucdavis.edu> > To: "Freesurfer support list" <freesurfer@nmr.mgh.harvard.edu> > Sent: Friday, April 25, 2014 2:10:29 AM > Subject: Re: [Freesurfer] Hippocampal subfields on 1.5 Tesla > > > > > 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 < alandarkene...@gmail.com> > 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 > Freesurfer@nmr.mgh.harvard.edu > 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 > Freesurfer@nmr.mgh.harvard.edu > 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 > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >
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