I¹d add that SNR may also change if you don¹t acquire as much data axially as you did sagittally. Really it¹s better to acquire your 3D T1w/T2w/FLAIR scans sagittally as this is most efficient.
Peace, Matt. On 4/8/16, 10:23 AM, "Bruce Fischl" <freesurfer-boun...@nmr.mgh.harvard.edu on behalf of fis...@nmr.mgh.harvard.edu> wrote: >Hi Gamaliel > >many things will change when you change the slice direction - amount of >wrap, possibly your FOV, slab-selection profile if your protocol is >slab-selective, and some types of distortion. These will all change the >image which will change our results. Of course even if you don't change >anything you won't get identical results if you scan twice, but our >longitudinal stream is pretty reliable. Andre van der Kouwe has >acquitisiton recommendations here: > >http://www.nmr.mgh.harvard.edu/~andre/FreeSurfer_recommended_morphometry_p >rotocols.pdf > >cheers >Bruce > >On Fri, 8 Apr 2016, Gamaliel >Huerta Urrea wrote: > >> >> >> 2016-04-08 12:09 GMT-03:00 Gamaliel Huerta Urrea >><gamaliel.hue...@uv.cl>: >> Hello Freesurfers >> I'm trying to do volumetric reconstruction, i already have done this >> but. i wanted to see if for the same subject, with different >> directions of slices i have the same result, and obviously i had >> different results of volumetric measures. i have used the sequence >> FSPGR T1 ponderation, with the same parameters for both data >> acquisition; with voxel 1 mm3, but the direction is changed in both >> studies axial and sagittal. Both studies are in *.dcm format, and i >> used the next command for convert dicom to .mgz and after to apply >> recon-all process: >> >> 1. >> >> mri_convert firstdicom.dcm 001.mgz >> >> I would like to know why would i have this problem? >> >> There is some specific slice direction for this kind of study which is >> suitable ? >> >> I'm interested in cerebellum volumetric information. I attached my >> results for volumetry. >> >> Cheers >> >> -- >> Gamaliel Huerta >> Ingeniero Civil Biomédico >> HealthCare Analytics >> Centro Interdisciplinario de Innovación en Salud >> Universidad de Valparaíso >> >> >> >> >> -- >> Gamaliel Huerta >> Ingeniero Civil Biomédico >> HealthCare Analytics >> Centro Interdisciplinario de Innovación en Salud >> Universidad de Valparaíso >> >> >>_______________________________________________ >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
