P3–114: Quantitative evaluation of anthropomorphic brain phantoms for standardization of amyloid PET SUVrs in alzheimer's Multicenter Therapeutic Trials

We therefore wish to assess the impact on brain atrophy as measured by the boundary shift integral (BSI) of changing from non-accelerated to accelerated MRI acquisitions over a 12-month interval.Methods: Accelerated and non-accelerated scans of 55 early mild cognitive impairment subjects, acquired in the same scanning session, were downloaded from ADNI. Brain regions were automatically delineated by Multi-Atlas Propagation and Segmentation, visually checked andmanually edited if necessary. BSIswere calculated using both a non-accelerated baseline scan and non-accelerated repeat scans (i.e. consistent acquisition), and a non-accelerated baseline scan and an accelerated repeat scan (i.e. changed acquisition). Results: Mean BSI from changed acquisition was 0.12%/year (p1⁄40.02) lower than consistent acquisition (see Table 1 and Fig. 1). Fig. 1(a) shows that most of the differences are close to zero, and 10 BSIs have differences > 0.5%/ year, which consists of all the 3 BSIs from site 21 (marked in red). There was no evidence that the standard deviations were different (p1⁄40.7). Conclusions: We found a relatively small (w0.1% of brain volume) effect on brain volume change in BSI when changing from non-accelerated to accelerated MRI during follow-up. This difference isw1/5 of the annual atrophy rate in normal aging in elderly subjects (w0.5%/year). However there did appear to be site-specific differences; this may reflect greater differences in the accelerated acquisition on that scanner. Going from non-accelerated baseline to acceleratedMRI for follow-up may have surprisingly little effect