Multiple boli arterial spin labeling for high signal-to-noise rodent brain perfusion imaging

PurposeA systematic method is proposed for optimizing a promising preclinical arterial spin labeling (ASL) sequence based on the use of a train of adiabatic radiofrequency pulses labeling successive boli of blood water. MethodsThe sequence optimization is performed and evaluated using brain imaging experiments in mice and in rats. It involves the investigation of several parameters, ranging from the number of adiabatic pulses and labeling duration to the properties of the adiabatic hyperbolic secant pulses (ie, amplitude and frequency modulation). ResultsSpecies-dependent parameters are identified, allowing for robust fast optimization protocols to be introduced. The resulting optimized multiple boli ASL (mbASL) sequence provides with significantly higher average signal-to-noise ratios (SNR) per voxel volume than currently encountered in ASL studies (278mm(-3) in mice and 172mm(-3) in rats). Comparing with the commonly used flow-sensitive alternating inversion recovery technique (FAIR), mbASL-to-FAIR SNR ratios reach 203% for mice and 725% for rats. ConclusionWhen properly optimized, mbASL can offer a robust, high SNR ASL alternative for rodent brain perfusion studies Magn Reson Med 79:1020-1030, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.