Hello, I was wondering if I could get some clarification regarding the longitudinal measure of rate of change in sulci depth. In our study we have a patient population that participated in an intervention and a similar group of wait list controls. We have scans for pre and post intervention timepoints. I have ran the longitudinal analysis in QDEC looking at the thickness change measures, however I was also interested in the sulc measures. I was able to get the analysis to run with the new measures long.sulc-rate etc. However I am having a hard time conceptualizing the meaning of the results. Does a negative rate change indicate either a deepening or a shallowing of the sulci? Is the opposite the case for gyral regions? Any advice would be greatly appreciated. -Andrew
Hi Andrew,
I don't know how the sulc measure gets computed and what it means exactly. Probably someone else can tell.
The longitudinal treatment is identical as for example thickness. The slope (rate) is a fit into the data across time. So a negative slope means a reduction in whatever is measured. Once you find out what exactly that measurement describes, you'll know what a smaller value of that measurements means. Sorry, I can't be of more help.
Best, Martin
On 02/21/2013 12:14 PM, O'Shea,Andrew wrote:
Hello, I was wondering if I could get some clarification regarding the longitudinal measure of rate of change in sulci depth. In our study we have a patient population that participated in an intervention and a similar group of wait list controls. We have scans for pre and post intervention timepoints. I have ran the longitudinal analysis in QDEC looking at the thickness change measures, however I was also interested in the sulc measures. I was able to get the analysis to run with the new measures long.sulc-rate etc. However I am having a hard time conceptualizing the meaning of the results. Does a negative rate change indicate either a deepening or a shallowing of the sulci? Is the opposite the case for gyral regions? Any advice would be greatly appreciated. -Andrew
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Sulc is the integrated dot product of the surface normal and the movement vectors during inflation Bruce
On Feb 22, 2013, at 12:25 PM, Martin Reuter mreuter@nmr.mgh.harvard.edu wrote:
Hi Andrew,
I don't know how the sulc measure gets computed and what it means exactly. Probably someone else can tell.
The longitudinal treatment is identical as for example thickness. The slope (rate) is a fit into the data across time. So a negative slope means a reduction in whatever is measured. Once you find out what exactly that measurement describes, you'll know what a smaller value of that measurements means. Sorry, I can't be of more help.
Best, Martin
On 02/21/2013 12:14 PM, O'Shea,Andrew wrote:
Hello, I was wondering if I could get some clarification regarding the longitudinal measure of rate of change in sulci depth. In our study we have a patient population that participated in an intervention and a similar group of wait list controls. We have scans for pre and post intervention timepoints. I have ran the longitudinal analysis in QDEC looking at the thickness change measures, however I was also interested in the sulc measures. I was able to get the analysis to run with the new measures long.sulc-rate etc. However I am having a hard time conceptualizing the meaning of the results. Does a negative rate change indicate either a deepening or a shallowing of the sulci? Is the opposite the case for gyral regions? Any advice would be greatly appreciated. -Andrew
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
-- Dr. Martin Reuter Assistant in Neuroscience - Massachusetts General Hospital Instructor in Neurology - Harvard Medical School MGH / HMS / MIT
A.A.Martinos Center for Biomedical Imaging 149 Thirteenth Street, Suite 2301 Charlestown, MA 02129
Phone: +1-617-724-5652 Email: mreuter@nmr.mgh.harvard.edu reuter@mit.edu Web : http://reuter.mit.edu _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
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O'Shea,Andrew