Low Power Adiabatic Inversion for Arterial Spin Labeling
Ovidiu Cristian Andronesi 1 , Uvo C. Hoelscher 2 , Himanshu Bhat 3 , Keith Heberlein 3 , and Bruce R. Rosen 1
Martinos Center for Biomedical Imaging,
Department of Radiology, Massachusetts General Hospital,
Harvard Medical School, Boston, MA, United States,
Healthcare, AG, Erlangen, Bayern, Germany,
Healthcare USA, Boston, MA, United States
Improving SNR is critical for the ASL methods. Inversion
of magnetization of the blood spins is a main factor
responsible for the SNR in ASL. With the ongoing trend
in the development of MR hardware towards large-bore
scanners and the active control of the RFPA duty cycle
there is an increased need for efficient and low-power
adiabatic inversion. Here we present the use of Gradient
Offset Independent Adiabaticity GOIA-W(16,4) pulses for
low power adiabatic tagging of blood in ASL sequences.
GOIA pulses require only half of the B1max of the FOCI
pulses that are typically used in ASL. Hence, the B1max
of GOIA pulses is not clipped and can be increased above
the adiabatic threshold allowing to compensate for B1
inhomogeneity. Perfusion maps obtained in human brain
show that SNR is improved overall with GOIA pulses.
Largest SNR gain (50%) is noticed especially in the
middle of the brain as expected from simulations.
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