Effect of Tag Dispersion On Fast ASL Methods
Hernandez-Garcia L, Lee G, Noll D
University of Michigan
A model for the turbo-CASL perfusion signal in the presence of dispersion of the tag bolus is presented. Simulations demonstrate an attenuation of the turbo CASL signal peak that becomes more pronounced with increasing tag dispersion. This signal attenuation is less severe for traditional CASL acquisitions with long TR values. Fits to two-coil turbo-CASL data from a human subject were improved significantly when tag dispersion was allowed. The average FWHM of the fitted Rayleigh PDF dispersion kernel was 0.89 seconds. Flow estimates for gray matter voxels increased by 15.6% on average when dispersion was taken into account.