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Principal Investigator  
Principal Investigator's Name: Alan Wilman
Institution: University of Alberta
Department: Biomedical Engineering
Proposed Analysis: The ADNI1 dataset includes dual echo fast spin echo (FSE) and a B1 calibration scan. A simple exponential fit may be used to obtain the transverse relaxation time (T2) from the FSE data. This has been performed with the ADNI data set (CM Bauer NeuroImage 2010). However, the results indicated insufficient sensitivity to detect FSE-T2 changes between normal aging, MCI, and AD and that FSE-T2 is highly variable across scanner vendors. We have recently developed means to remove T2 variability arising from slice profile and radiofrequency field variations. We have demonstrated that we can perform T2 mapping using dual echo FSE in cases where the refocusing is imperfect and demonstrated the value of this method to supply accurate T2 and remove variation between subjects due to radiofrequency field and slice profile effects. We expect this method will also remove variation between scanner types. We hypothesize that our method (stimulated echo compensation)can provide both more accurate T2 values and less variability, which will enable analysis of differences in T2 mapping between subject groups. We have two initial objectives: 1) A technical objective to demonstrate that our method can improve T2 mapping over standard exponential fitting using the ADNI1 dual echo data and B1 calibration scans in a small subset at 1.5T and 3.0 T. 2)With our improved T2 fitting, examine the cross sectional relationship between healthy subjects, MCI and dementia patients. Relate T2 changes to atrophy as measured from MPRAGE. Examine relationships to cognitive testing. In conclusion, T2, when corrected for intersubject and scanner variations due to flip angle effects, may provide a sensitive marker to distinguish changes arising from dementia. We are interested in accessing the ADNI1 MRI data sets including the dual echo FSE (PD+T2-weighted), B1 calibration scans and the MPRAGE data. If granted we would like to begin access in June 2014.
Additional Investigators