Andrew David Hahn1, Andrew S. Nencka1, Daniel B. Rowe1
1Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
The contribution of various not-of-interest global physiologic phenomena to phase time series in MRI is well documented and poses experimental challenges for complex data analysis techniques. Recently published results demonstrated that correction of global temporal variations in the main magnetic field, which directly impact phase, significantly reduces temporal phase variability, ultimately restoring statistical power of local phenomena in complex-valued functional MRI (fMRI) regression analysis. When this correction is applied in conjunction with an fMRI analysis of phase-only activation, local task related phase changes that are statistically invisible in the raw signal, become detectable with high levels of significance.
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