Jang-Yeon Park1, Michael Garwood1
1Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, MN, USA
Frequency-modulated (FM) pulses have advantages for spin-echo experiments, such as the ability to produce a broadband and B1-insensitive π rotation. However, such use leads to a non-linear phase of the transverse magnetization. Here, general conditions to compensate the non-linear phase across a slice are proposed for multi-slice spin-echo MRI using π/2 and π hyperbolic secant (HS) pulses. They provide excellent slice-selection and partial B1-insensitivity, as well as a shorter echo-time and lower power deposition than a method using a pair of π HS pulses. One of the conditions also offers a new possibility for chemical-shift selected or susceptibility-weighted imaging.
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