Hi Bruce, I think that unnormalized sulcal depth would be useful. However, I am also curious what the units are in the standard output, because they appear to not be z-score standardized in each hemisphere.
Thanks again, Simon >H I Simon >Do you need the unnormalized sulc? It would be pretty easy to put something in >to generate it >Bruce > >> On Oct 22, 2015, at 3:23 PM, Simon Vandekar <[email protected]> >> wrote: >> >> Hi Bruce, >> >> I chose a random subject from the ADNI dataset and computed the mean and >> variance for the left and right hemispheres separately. It looks like the >> mean is close to 0, however the variance is not 1. Do you think it is >> possible that the surfaces are demeaned, but the units are still something >> meaningful (i.e. not unitless)? >> >> >> sulc = read.table('rh.sulc.asc', header=FALSE, col.names=c('v', 'x', 'y', >> 'z', 'sulc')) >>> mean(sulc$sulc) >> [1] -1.236923e-08 >> >>> var(sulc$sulc) >> [1] 0.3276958 >> >>> quantile(sulc$sulc) >> 0% 25% 50% 75% 100% >> -1.72503 -0.42128 -0.03963 0.40072 1.80980 >> >> >> Thanks again, >> Simon >> >> >> >> >> >> Hi Simon >> >> they are originally mm, but I believe we z-score normalize them so that >> the sulc file is 0 mean and unit variance. >> >> cheers >> Bruce >> On Wed, 21 Oct 2015, Simon >> Vandekar wrote: >> >>> Dear Freesurfer experts, >>> >>> >>> I am reading the manuscript "Cortical Surface-Based Analysis II: Inflation, >>> Flattening, and a Surface-Based Coordinate System" by Fischl, Sereno, and >>> Dale (1999) where the estimation of sulcal depth is described on page 199, >>> however from the description I am still unsure of the exact units of sulcal >>> depth. >>> Are the units for sulcal depth in mm or are they in arbitrary units? >>> >>> Thanks in advance, >>> Simon _______________________________________________ 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.
