title: Direct design of 2D RF pulses using matrix inversion.
abstract: Multi-dimensional pulses are frequently used in MRI for applications such as targeted excitation, fat-water separation or metabolic imaging with hyperpolarised (13)C compounds. For the design, the problem is typically separated into the different dimensions. In this work, a method to directly design two-dimensional pulses using the small-tip angle approximation is introduced based on a direct matrix representation. The numerical problem is solved in a single step directly in two dimensions by matrix inversion. Exemplary spectral-spatial excitation and spatio-temporal encoding (SPEN) pulses are designed and validated. The main benefits of the direct design approach include a reduction of artefacts in case of spectral-spatial pulses, a simple and straightforward computer implementation and high flexibility in the pulse design.
authors.affiliation: GE Global Research, Freisinger Landstr. 50, 85748 Garching bei München, Germany. Electronic address: Rolf.Schulte@research.ge.com.
authors.forename: Rolf F
authors.initials: RF
authors.lastname: Schulte
authors.forename: Florian
authors.initials: F
authors.lastname: Wiesinger
keywords: (13)C; 2D RF pulses; CSI; EPI; FOV; MRS; Metabolic imaging; RF; ROI; Radio-frequency pulses; SNR; SPEN; SPSP; Spatio-temporal encoding; Spectral–spatial excitation; chemical-shift imaging; echo-planar imaging; field of view; magnetic resonance spectroscopy; radio-frequency; region of interest; signal-to-noise ratio; spatio-temporal encoding; spectral–spatial