#8 What do extracted values from ROI signify?

[Narges]

Hi Matthew,

I hope you're doing well.

I have a question regarding ROI values obtained from MarsBar from each subject. My values are between 0 to 1 and I would like to know what they exactly represent. I can't find any source that explains this. I'd really appreciate your help.

These are the steps I followed:
- I preprocessed T1 scans using SPM12 to obtain mwrp1s grey matter segments.
- I used aal3 atlas for marsbar to build my ROI.
- I extracted ROI data using the following options:
- extract ROI data (full options);
- SPM design: No
- model: other
- No of subject: 1 - I chose mwrp1s images
- Scaling from: raw data
- scale grand mean = 0

The Y values that I obtained in MarsBar are between 0 to 1 (or higher but very close to 1). What is the most accurate term to use for them? Grey matter intensity, volume, or density? Is there a unit for these values?

Thanks a lot for your help,

Narges