Measurement of functional CBF is challenging due to inherently low SNR and signal amplitudes, especially in regions of negative BOLD response. Here, multi-echo center-out EPI is introduced which allows for simultaneous measurement of functional changes in CBF and T2* with improved sensitivity. Using a visual stimulus inducing positive and negative BOLD responses, a linear relationship between absolute changes in CBF and T2* along both positive and negative directions was found with similar coupling ratios. Negative absolute functional CBF changes were found to be almost independent of the baseline CBF, in agreement with previous work on the positive BOLD response.
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