Question

Question Posted 11/25/14:
Hello, I run a medical imaging CRO. We have been approached by a client to do visual ratings of the raw florbetapir data. Is the raw data available to us? Do you have a suggestion for the best available method to reconstruct the raw data for visual interpretation?

Many thanks,
Matthew
Response posted 11/25/14 by Bob Koeppe:
There are two interpretations of "raw" PET data that can lead to confusion. Typically "raw" PET data has referred to the unreconstructed sinogram data. However, the raw sinogram data can not be used to do visual ratings. In your case, the client must mean the original reconstructed images without subsequent processing, and hence they are already reconstructed. The raw sinogram data are not available at ADNI, only the original reconstructed florbetapir images. These are actually tagged as "original" at LONI. Images that have been manipulated (derived images) are labeled as either "pre-processed" (the images uploaded by our group at Michigan), or "processed" images or data (uploaded by one of several data analysis groups within ADNI. About the only thing you can do to the raw original images that would effect a visual read is to smooth them. The amount of smoothing would depend on the trade-off between resolution and "noise" that the reader is comfortable with. (i.e. more smoothing, less noise, but lower resolution.)