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NEWS & PUBLICATIONS

Scaled 2 Uploads
Wed, Oct 1, 2008

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.


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