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Anisha Keshavan edited The_papers_cited_here_add__.tex  over 8 years ago

Commit id: 0008c8a08a83b211334068aae93addadd9bb7c02

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The papers cited here add evidence for our hypothesis that different ROIs will have different scaling factors, due to regional differences in contrast, as shown in a VBM analysis by Tardiff and colleagues. I have The section has been  edited this section: as follows:    \textit{"We hypothesized that all differences in \textbf{regional} contrast and geometric distortion result in regional volumes that are consistently and linearly scaled from their true value. For a given region of interest (ROI), two mechanisms impact the final boundary definition: gradient nonlinearities cause distortion and, simultaneously, hardware (including scanner, field strength, and coils) and acquisition parameters modulate tissue contrast, adjusting the whole boundary. \textbf{Previously, Tardiff and colleagues have found that contrast-to-noise ratio and contrast inhomogeneity from various pulse sequences and scanner strengths cause regional biases in VBM\cite{tardif2010regional,tardif2009sensitivity}, and therefore we hypothesized that each ROI will scale differently at each site.} By imaging 12 subjects in 20 different scanners using varying acquisition schemes, we were able to estimate the scaling factor for each regional volume at each site..."}