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Abstract #0768

Can the Calibrated BOLD Scaling Factor M Be Estimated Just From R2′ in the Baseline State Without Administering Gases?

Nicholas P. Blockley1, Valerie E M Griffeth1, Richard B. Buxton1

1Center for fMRI, Department of Radiology, University of California San Diego, La Jolla, CA, USA

The calibrated BOLD technique typically uses a respiratory challenge to measure the calibration constant M. This is both time consuming and uncomfortable for the participant. Here we consider the possibility of determining M using measurements of R2′ made using an asymmetric spin echo experiment without administering any gases. The key question in this hypothesis is what fraction of the R2* change on activation can be captured by R2′ measurements in the baseline state?