http://adni.loni.ucla.edu Alzheimer’s Disease Neuroimaging Initiative Wed, 12 Jun 2013 19:07:01 +0000 en hourly 1 http://wordpress.org/?v=3.3.2 http://adni.loni.ucla.edu/scaled-2-uploads/ http://adni.loni.ucla.edu/scaled-2-uploads/#comments Wed, 01 Oct 2008 21:53:42 +0000 blee http://adni.loni.ucla.edu/?p=3474 As of 10/01/2008 pre-processed files uploaded to LONI from Mayo may be labeled as either *_scaled or *_scaled_2. Scaled_2 files were rescaled by disabling the scaling on the axis or axes for which the phantom scaling may be unreliable. This occurred in two situations. One, replacing the phantom results in unreliable across time scaling in the AP dimension. Two, scaling in the SI dimension was unreliable on early Philips 1.5T scans because the auto shim function was inadvertently disabled in the first version of the distributed protocol. Our approach was to set scaling to a value of 1.0 on the appropriate axes for scans where we were not confident of the accuracy of the phantom based scaling. Attached is a table containing all of the Scale_2 images re-uploaded to LONI listed by LONI Series ID, Original Pre-Processed Image Number and New Pre-Processed Image number. Subject scaling using the phantom had the AP scaling factor set to 1.0 if the phantom was replaced at the site for all scans done with the earlier phantom. Philips 1.5T sites were rescaled with SI set to 1.0 as ASO (auto shim on) is not included in the DICOM series description. There are 2 sites that are not included in this count: site 100 (Boston) 1.5T and 3T, and site 068 (MUSC) 1.5T. Issues with these 2 sites are still not resolved.

• Download a summary table of 068 re-scaled images corrected for a phantom replacement (not scaled in the AP direction) and ASO (not scaled in the SI direction).
• Download a summary table of pre-processed MRI file uploads to LONI from Mayo

]]> http://adni.loni.ucla.edu/scaled-2-uploads/feed/ 0 http://adni.loni.ucla.edu/duplicate-scaled-images/ http://adni.loni.ucla.edu/duplicate-scaled-images/#comments Thu, 05 Jun 2008 19:33:37 +0000 cmena http://beta.adni.loni.ucla.edu/?p=33 A number of scaled images were uploaded in duplicate. They have now been deleted. All users should refrain from analyzing the following Image IDs if they were downloaded prior to 21 Sept 07: 45104, 38794, 45203, 46409, 47058, 34420, 48761, 60501, 60490, 42525

]]> http://adni.loni.ucla.edu/duplicate-scaled-images/feed/ 0 http://adni.loni.ucla.edu/philips-scanners-image-scaling/ http://adni.loni.ucla.edu/philips-scanners-image-scaling/#comments Wed, 04 Jun 2008 19:37:15 +0000 cmena http://beta.adni.loni.ucla.edu/?p=34 The ADNI MRI core has uncovered a potential concern about the accuracy of image scaling in the frequency encode direction on Philips 1.5T systems. This problem is currently under investigation. For the time being, we suggest that investigators use this particular data judiciously. This message will be updated as more information becomes available.

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