Sensitivity to Bolus Dispersion in Continuous and Pulsed Multi-TI ASL Techniques

Roman Fleysher¹, Mark E. Wagshul¹, Michael L. Lipton¹, Craig A. Branch¹

Both Gaussian dissipation and single compartment Kety models are found to be inadequate for description of ASL experiments for two major reasons: 1) bolus disperses continuously as it travels down the vascular tree and must be modeled as such all the way to the capillary level and 2) exchange through the capillary wall is not instantaneous. We use more realistic simulations with continuous bolus dispersion and restricted water permeability of capillary walls to ascertain sensitivity of CASL, ITS-FAIR and Quasar ASL techniques to bolus dispersion. Quasar is found to handle bolus dispersion most effectively at 20 degree flip angle.