Signal-to-noise ratio = mean / standard deviation On Tue, 18 Mar 2014, Yuko Yotsumoto wrote:
> Anastasia, > > Thank you so much for your reply. > > So I should calculate the mean and s.d. of the values of the low-b within the > white matter region for each subject, and compare those numbers between > groups. > Is it correct to say that the higher mean values indicate larger SNR? > > Yuko > > On Mar 18, 2014, at 12:53 AM, Anastasia Yendiki wrote: > >> >> Hi Yuko - You can use the low-b images and compute the SNR of those images >> inside a mask of the white matter. Because dt_recon computes a registration >> from the diffusion to the structural data, you can use that registration to >> map the white matter label from the freesurfer segmentation (aseg) to the >> diffusion data. Then calculate the mean and standard deviation of the values >> of the low-b images inside that white matter mask. >> >> Hope this helps, >> a.y >> >> On Mon, 17 Mar 2014, Yuko Yotsumoto wrote: >> >>> Hello Freesurfers, >>> I have DTI data for two groups of subjects, and were asked SNR for each >>> group. >>> I did ROI analysis on FA values, therefore, I do not have the averaged DTI >>> data. >>> I am wondering if there is any way to compute SNR from dt_recon output. It >>> doesn't have to be the ROI specific SNR values, I just need SNR for the >>> whole DTI data for each group. >>> Any suggestions will be appreciated! >>> Yuko Yotsumoto >>> --- >>> ------------------------------------------------------------- >>> Yuko Yotsumoto, Ph. D. >>> Associate Professor >>> The University of Tokyo, Department of Life Sciences >>> Bldg #2, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902 Japan >>> phone : (+81)-3-5454-4332 >>> E-mail: cy...@mail.ecc.u-tokyo.ac.jp >> _______________________________________________ >> 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
