Dear all,
Excuse if these are simple questions but I am a bit confused on the significance of the volume measures.
1. Are the volumes of ROIs calculated after normalization?
2. If volumes are calculated post-normalization, why is correction for eTIV needed?
3. What is the quickest way to correct for eTIV?
Thank you. Dorian TJU
On 10/24/2013 10:37 AM, Dorian P. wrote:
Dear all,
Excuse if these are simple questions but I am a bit confused on the significance of the volume measures.
- Are the volumes of ROIs calculated after normalization?
No, everything is done in native space.
- If volumes are calculated post-normalization, why is correction for
eTIV needed?
- What is the quickest way to correct for eTIV?
Not sure what you mean by the "quickest". Usually the ROI volumes are divided by the eTIV or the eTIV is used as a regressor doug
Thank you. Dorian TJU
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
Thank you Douglas.
The eTIV has values like 1543825. Dividing ROIs by this value would create very small values.
Is there a standard TIV (i.e. from the talairach brain) to use as denominator for creating a ratio value? Or what is the best way to create a reasonable factor (i.e. 0.7-1.3) to correct/normalize roi volumes?
Dorian
2013/10/24 Douglas N Greve greve@nmr.mgh.harvard.edu
On 10/24/2013 10:37 AM, Dorian P. wrote:
Dear all,
Excuse if these are simple questions but I am a bit confused on the significance of the volume measures.
- Are the volumes of ROIs calculated after normalization?
No, everything is done in native space.
- If volumes are calculated post-normalization, why is correction for
eTIV needed?
- What is the quickest way to correct for eTIV?
Not sure what you mean by the "quickest". Usually the ROI volumes are divided by the eTIV or the eTIV is used as a regressor doug
Thank you. Dorian TJU
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
-- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422
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Why is a small # a problem? It simply represents the fraction of the total intracranial volume occupied by that structure.
cheers Bruce On Thu, 24 Oct 2013, Dorian P. wrote:
Thank you Douglas. The eTIV has values like 1543825. Dividing ROIs by this value would create very small values.
Is there a standard TIV (i.e. from the talairach brain) to use as denominator for creating a ratio value? Or what is the best way to create a reasonable factor (i.e. 0.7-1.3) to correct/normalize roi volumes?
Dorian
2013/10/24 Douglas N Greve greve@nmr.mgh.harvard.edu
On 10/24/2013 10:37 AM, Dorian P. wrote: > Dear all, > > Excuse if these are simple questions but I am a bit confused on the > significance of the volume measures. > > 1. Are the volumes of ROIs calculated after normalization?No, everything is done in native space.
- If volumes are calculated post-normalization, why is correction
for
eTIV needed?
- What is the quickest way to correct for eTIV?
Not sure what you mean by the "quickest". Usually the ROI volumes are divided by the eTIV or the eTIV is used as a regressor doug
Thank you. Dorian TJU
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
-- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422
Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
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.
What is the problem with small values? You can multiply them by 100 to give you percent of brain. Or multiply them by 1000 to give you tenths of percents
doug
On 10/24/2013 12:58 PM, Dorian P. wrote:
Thank you Douglas.
The eTIV has values like 1543825. Dividing ROIs by this value would create very small values.
Is there a standard TIV (i.e. from the talairach brain) to use as denominator for creating a ratio value? Or what is the best way to create a reasonable factor (i.e. 0.7-1.3) to correct/normalize roi volumes?
Dorian
2013/10/24 Douglas N Greve <greve@nmr.mgh.harvard.edu mailto:greve@nmr.mgh.harvard.edu>
On 10/24/2013 10:37 AM, Dorian P. wrote: > Dear all, > > Excuse if these are simple questions but I am a bit confused on the > significance of the volume measures. > > 1. Are the volumes of ROIs calculated after normalization? No, everything is done in native space. > > 2. If volumes are calculated post-normalization, why is correction for > eTIV needed? > > 3. What is the quickest way to correct for eTIV? Not sure what you mean by the "quickest". Usually the ROI volumes are divided by the eTIV or the eTIV is used as a regressor doug > > Thank you. > Dorian > TJU > > > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu> > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer -- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu> Phone Number: 617-724-2358 <tel:617-724-2358> Fax: 617-726-7422 <tel:617-726-7422> Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting <http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting> FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html <http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html> Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto: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.
Thank You Douglas. I figured out that multiplicating by a fixed value could make the trick.
Have a good weekend.
Dorian
2013/10/29 Douglas N Greve greve@nmr.mgh.harvard.edu
What is the problem with small values? You can multiply them by 100 to give you percent of brain. Or multiply them by 1000 to give you tenths of percents
doug
On 10/24/2013 12:58 PM, Dorian P. wrote:
Thank you Douglas.
The eTIV has values like 1543825. Dividing ROIs by this value would create very small values.
Is there a standard TIV (i.e. from the talairach brain) to use as denominator for creating a ratio value? Or what is the best way to create a reasonable factor (i.e. 0.7-1.3) to correct/normalize roi volumes?
Dorian
2013/10/24 Douglas N Greve <greve@nmr.mgh.harvard.edu <mailto: greve@nmr.mgh.harvard.**edu greve@nmr.mgh.harvard.edu>>
On 10/24/2013 10:37 AM, Dorian P. wrote: > Dear all, > > Excuse if these are simple questions but I am a bit confused on the > significance of the volume measures. > > 1. Are the volumes of ROIs calculated after normalization? No, everything is done in native space. > > 2. If volumes are calculated post-normalization, why is correction for > eTIV needed? > > 3. What is the quickest way to correct for eTIV? Not sure what you mean by the "quickest". Usually the ROI volumes are divided by the eTIV or the eTIV is used as a regressor doug > > Thank you. > Dorian > TJU > > > ______________________________**_________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu>> https://mail.nmr.mgh.harvard.**edu/mailman/listinfo/**freesurfer<https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer> -- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.**edu<greve@nmr.mgh.harvard.edu>Phone Number: 617-724-2358 <tel:617-724-2358> Fax: 617-726-7422 <tel:617-726-7422> Bugs: surfer.nmr.mgh.harvard.edu/**fswiki/BugReporting<http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting> <http://surfer.nmr.mgh.**harvard.edu/fswiki/**BugReporting<http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting>FileDrop: https://gate.nmr.mgh.harvard.**edu/filedrop2<https://gate.nmr.mgh.harvard.edu/filedrop2> www.nmr.mgh.harvard.edu/**facility/filedrop/index.html<http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html> <http://www.nmr.mgh.harvard.**edu/facility/filedrop/index.**html<http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html>Outgoing: ftp://surfer.nmr.mgh.harvard.**edu/transfer/outgoing/flat/**greve/<ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/> ______________________________**_________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.**harvard.edu Freesurfer@nmr.mgh.harvard.edu>
https://mail.nmr.mgh.harvard.**edu/mailman/listinfo/**freesurfer<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<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.-- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422
Bugs: surfer.nmr.mgh.harvard.edu/**fswiki/BugReportinghttp://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.**edu/filedrop2https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/**facility/filedrop/index.htmlhttp://www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.**edu/transfer/outgoing/flat/** greve/ ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
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