Question

Question Posted 11/17/16:
Dear Experts. I've collect PET images across ADNI1/ADNIGO/ADNI2 with preprocessing step 3 and with all types of tracers (FDG, AV45, PIB, etc.). I'd like to tell which tracer was implemented in a specific image, and I can only find it within the "Description" column in the csv file downloaded from Image Collection page. For example: "AV45 Coreg, Avg, Standardized Image and Voxel Size <- ADNI Brain PET: Raw AV45".

By extracting the first character in the string, four types of character can be found: "AV1451", "AV45", "AV45-Early", "", "PIB".

where I infer "" to be image implemented by FDG.

My question is:
1. What does "AV45-Early" means ? Is it the same as "AV45" ?
2. Is there any better way to identify the type of tracer ?

thanks

Philip Lin
PhD student
Response posted 11/17/16 by Robert Koeppe:
The "Early AV-45" scans are acquired from 0-20 min post-injection. The processed images are merely a sum of some of the "early" frames and more closely represent blood flow than amyloid. It is the same tracer (AV45), but not at a time where one can measure amyloid deposition.