Question Posted 01/27/17:
Dear experts,
Looking at the dataset 'adnimerge' I found a lot of subjects without information on the 'FLDSTRENG' field, although they have other MRI information (FSVERSION, ROI volumes, etc). Where I can find this missing information?

Response posted 02/01/17 by Danielle:
You can refer to the variable FSVERSION. Based on the corresponding data file, it looks like FreeSurfer version 4.3 is all 1.5T. If you see an RID>2000 (so a newly recruited ADNI-GO or ADNI-2 participant), the field strength is 3T, since that was the protocol for ADNI-GO and ADNI-2.