Diffs
| <<O>> Difference Topic ADNIPETCore (r1.28 - 01 May 2009 - BobKoeppe) |
ADNI PET CorePET Core News | ||||||||
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New Site with PET scanner change:Four more ADNI sites have just replaced their PET scanners (the other sites are listed under "Old Warnings"). As mentioned below, investigators should be aware of resolution differences between scanners, hence should consider analyzing the PET data that has been matched for resolution. This is the 4th of the 4 pre-processed image files that get uploaded to LONI by the QC group. These have a uniform 160x160x96 1.5 mm3 grid and isotropic ~8mm FWHM resolution. Another important consideration is that the apparent size of the brain can be different for different scanners. For example, '20 cm' in size on the older Siemens Accel and Exact is smaller than '20' cm in the newer BioGraph HiRez scanner. As with the previous PET scanner replacements, all "pre-processed" images for the new scanner have been adjusted to correct for these differences. This is important for within-subject analyses. | |||||||
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Replacement scan for 033_S_1285 | |||||||
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*Site 009 Baylor: All prior scans were done on a Siemens Ecat Exact 47-slice scanner. Their new scanner is a GE Discovery ST 47-slice scanner For the new Discovery ST scans, the x,y voxel size is reduced from 2.00 mm to 1.945 mm to match the size of the Exact scanner. The z dimension of the scans for these subjects are reduced from 3.27 to 3.24 mm. | |||||||
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This subject originally had a scan on 8/28/08. This scan was acquired incorrectly at 18m (since this subject is not an MCI subject and hence should not have had an 18m scan). At that time it was decided to use this scan instead of the 24m PET scan. Hence, we initially passed this scan as this subject's 24m FDG scan with the plan was to skip the scan at 24 months. However, the site scanned the subject again at 24m anyway (scan date 2/23/09). This scan has been QC'd and is now the official 24m FDG scan for this subject. The previous scan from 8/28/09 has now been failed, and is no longer accessible from LONI. The new 24M FDG scan for 033_S_1285 was approved on March 12th, 2009. If this scan was downloaded before March 13, 2009, please download again and replace. Downloads March 13, 2009 or after will give the newer scan. | |||||||
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*Site 021 Baylor: All prior scans were done on a GE Advance 35-slice scanner. Their new scanner is a GE Discovery STE 47-slice scanner There are no changes in voxel sizes. | |||||||
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*Site 057 and 126 (St. Joe and Parkwood (sharing scanner): All prior scans were done on a GE Discovery LS 35-slice scanner. Their new scanner is a GE Discovery STE 47-slice scanner There are no changes in voxel sizes. -- BobKoeppe - 02 Dec 2008 | |||||||
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-- BobKoeppe - 20 April 2009 | |||||||
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Old warnings: | ||||||||
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New Site with PET scanner change:Four more ADNI sites have just replaced their PET scanners (the other sites are listed under "Old Warnings"). As mentioned below, investigators should be aware of resolution differences between scanners, hence should consider analyzing the PET data that has been matched for resolution. This is the 4th of the 4 pre-processed image files that get uploaded to LONI by the QC group. These have a uniform 160x160x96 1.5 mm3 grid and isotropic ~8mm FWHM resolution. Another important consideration is that the apparent size of the brain can be different for different scanners. For example, '20 cm' in size on the older Siemens Accel and Exact is smaller than '20' cm in the newer BioGraph HiRez scanner. As with the previous PET scanner replacements, all "pre-processed" images for the new scanner have been adjusted to correct for these differences. This is important for within-subject analyses. *Site 009 Baylor: All prior scans were done on a Siemens Ecat Exact 47-slice scanner. Their new scanner is a GE Discovery ST 47-slice scanner For the new Discovery ST scans, the x,y voxel size is reduced from 2.00 mm to 1.945 mm to match the size of the Exact scanner. The z dimension of the scans for these subjects are reduced from 3.27 to 3.24 mm. *Site 021 Baylor: All prior scans were done on a GE Advance 35-slice scanner. Their new scanner is a GE Discovery STE 47-slice scanner There are no changes in voxel sizes. *Site 057 and 126 (St. Joe and Parkwood (sharing scanner): All prior scans were done on a GE Discovery LS 35-slice scanner. Their new scanner is a GE Discovery STE 47-slice scanner There are no changes in voxel sizes. | |||||||
| A fourth ADNI site has just replaced their PET scanner (the other 3 sites are listed under "Old Warnings"). As mentioned below, investigators should be aware of resolution differences between scanners, hence should consider analyzing the PET data that has been matched for resolution. This is the 4th of the 4 pre-processed image files that get uploaded to LONI by the QC group. These have a uniform 160x160x96 1.5 mm3 grid and isotropic ~8mm FWHM resolution. Another important consideration is that the apparent size of the brain can be different for different scanners. For example, '20 cm' in size on the older Siemens Accel and Exact is smaller than '20' cm in the newer BioGraph HiRez scanner. As with the previous 3 PET scanner replacements, all "pre-processed" images for the new scanner have been adjusted to correct for these differences. This is important for within-subject analyses. *Site 003 USC: All scans acquired prior to 2008 were performed on an Siemens BioGraph LSO scanner, the older 47 slice model. Their new scanner is a BioGraph LSO HiRez 81 slice scanner, and was brought on-line in March 2008. To date (April 2, 2008), two scans have been uploaded to LONI, 003_S_1057 (12m scan) and 003_S_1074 (12m scan). For the new BioGraph HiRez scans, the x,y voxel size is unchanged, while the z dimension of the scans for subjects that have earlier scans on the old scanner has been reduced from 2.0205 to 1.995 mm. | ||||||||
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Revision r1.27 - 02 Feb 2009 - 20:57 - BobKoeppe Revision r1.28 - 01 May 2009 - 15:14 - BobKoeppe |