T2* Modulation of Functional Connectivity using a Multi-Echo Strategy

Changwei W. Wu¹, Hong Gu¹, Qihong Zou¹, Hanbing Lu¹, Elliot a Stein¹, Yihong Yang¹

Spatial and spectral effects of T2* were assessed on low-frequency spontaneous fluctuations acquired at 3T. Using a mutlti-echo sequence, broad local (ipsilateral) connections but minimal long-distance (contralateral) connections were found at an ultra-low TE (7.7 ms) in the default-mode network. In frequency domain, the uniform spectral power at low TE indicated minimal T2*-weighted connectivity and the elevated spectral power with long TEs in the frequency range of 00.05 Hz, likely due to T2*-mediated neuronal activities. These results characterized the effects of transverse relaxation times on functional connectivity, which would be useful for the interpretation of resting-state fMRI studies.