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Abstract #1609

Latency and Echo-Time Dependence of the GRE-BOLD Signal in High-Resolution FMRI

Stefan Hetzer1, Toralf Mildner1, Thies H. Jochimsen1, Karsten Mller1, Torsten Schlumm1, Harald E. Mller1

1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

The relation between amplitude and latency of the BOLD signal was studied at 3T by use of high-resolution fMRI employing a center-out EPI sequence that allowed a minimum TE of 2 ms. The measured relaxation rate change δR2* during visual stimulation, i. e. the slope of the linear fit of the TE dependence and the corresponding intercept were found to increase with the BOLD latency. The δR2* increase over the total range of the BOLD latency was between 40 and 70%. In general, δR2* increased with image resolution which points to an underestimation of δR2* in low-resolution fMRI studies.