Robert C. Brand1, Nicholas P. Blockley1, Michael Chappell2, and Peter Jezzard1
1FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, 2IBME, University of Oxford, Oxford, United Kingdom
Clinical 3D CEST has been hindered by slow acquisition times and z-spectra artefacts that affect fitting. Here, we demonstrate various sequence improvements, including: 1) hexagonal gradient spoiling that minimises ghosting, shortens TR and reduces confounding T2 sensitivity; 2) low readout flip angles combined with symmetric z-spectrum sampling that better maintains the steady state between samples and eliminates the need for T1-restoration periods; and 3) exchange-rate matched 360° CEST pulses that reduce direct water saturation to minimise T1 sensitivity and increase CNR. Together, these improvements result in high-quality whole-brain 39-offset z-spectra measurements at 3mm isotropic resolution in 2:59 minutes.
