Several sites have made PET scanner changes between ADNI-1 and ADNI-GO. Please read the following notice before going to the list of scanner changes below:
***IMPORTANT NOTE*** As mentioned in a long ago posting, different PET scanner models are not completely consistent in voxel size. By this I mean that 10 mm on one scanner is not necessarily the same as 10 mm on a different scanner model. We have determined the relative “effective” voxel size of each scanner model. For some scanner models, this difference was greater than 2-3%; an important adjustment! For PET scanner changes that occurred during ADNI-1, we adjusted the voxel size on the newer scanner when needed, in order to keep the “apparent” size of the brains the same. HOWEVER, at the start of ADNI-GO, we are not adjusting voxel sizes for scans done on a different scanner than the original ADNI-1 scanner. The two main reasons for this are 1), we are starting AV-45 scans and did not want to adjust voxel sizes for these scans, and 2) this seemed like a logicial break-point in the ADNI project with many new subjects being recruited. HENCE, for subjects scanned with FDG in ADNI-1 and now scanned with FDG on a different scanner in ADNI-GO, the voxel size is not being adjusted, and the brain size in the ADNI-GO scan may appear to be different than in the ADNI-1 scan. The scanners most different in size are the ECAT Exact, the ECAT Accel, and the older 47-slice BioGraph PET/CT scanners. Changes from one Philips scanner model to another, or from one GE scanner model to another, are very small and not an issue. Scanner changes from one vendor to another are more of an issue, and changes from one of the three older models mentioned above, to any other scanner model are important to account for when doing longitudinal comparisons. QUESTIONS: contact Bob Koeppe (koeppe@umich.edu)
The following is a list of PET scanner changes from ADNI-1 to ADNI-GO (see previous postings for scanner changes during ADNI-1):
Site 009: changed from Siemens ECAT Exact to GE Discovery ST during ADNI-1, and changed again starting with ADNI-GO to GE Discovery LS
Site 022: changed from a mix of Phlips Allegro-Neuro (G-PET) and Philips Allegro during ADNI-1, to all Philips Allegro in ADNI-GO
Site 027: changed from a Philips Gemini GXL in ADNI-1, to a Philips Gemini-TF in ADNI-GO
Site 035: changed from a Siemens ECAT HR+ in ADNI-1, to a Siemens BioGraph TruePoint (Model 1094) in ADNI-GO
Site 073: changed from a Siemens ECAT HR+ in ADNI-1, to a GE Discovery STE in ADNI-GO
Site 098: changed from a Siemens ECAT Exact in ADNI-1, to a GE Discovery STE in ADNI-GO
Site 116: changed from a Siemens ECAT Accel in ADNI-1, to a GE Discovery ST in ADNI-GO
Site 130: changed from a Siemens ECAT BioGraph HiRez (model 1080) just before the end of ADNI-1, to a Siemens BioGraph mCT in ADNI-GO
Site 137: changed from a GE ADvance in ADNI-1, to a GE Discovery STE in ADNI-GO
Site 941: changed from a Philips Gemini GXL in ADNI-1, to a Philips Gemini-TF in ADNI-GO
Posted 3/22/11
Bob Koeppe
