Advanced design of MRI inversion pulses for inhomogeneous field conditions by optimal control. (2nd August 2022)

• Record Type: Journal Article
• Authors: Graf, Christina; Soellradl, Martin; Aigner, Christoph Stefan; Rund, Armin; Stollberger, Rudolf
• Is Part Of: NMR in biomedicine. Volume 35:Number 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-02
• Subjects: Inhomogeneous B0 and B1 -- MRI -- RF pulse design -- time‐optimal control; Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.4790
• Languages: English
• ISSNs: 0952-3480

Abstract

Summary: Non‐selective inversion pulses find widespread use in MRI applications, where requirements on them are increasingly demanding. With the use of high and ultra‐high field strength systems, robustness to Δ B 0 and B 1 + inhomogeneities, while tackling SAR and hardware limitations, has rapidly become important. In this work, we propose a time‐optimal control framework for the optimization of Δ B 0 ‐ and B 1 + ‐robust inversion pulses. Robustness is addressed by means of ensemble formulations, while allowing inclusion of hardware and energy limitations. The framework is flexible and performs excellently for various optimization goals. The optimization results are analyzed extensively in numerical experiments. Furthermore, they are validated, and compared with adiabatic RF pulses, in various phantom and in vivo measurements on a 3 T MRI system. Abstract : Δ B 0 ‐ and B 1 + ‐robust, time minimized inversion pulses are designed by optimal control. The optimized RF pulses are analyzed extensively numerically, and in phantom and in vivo measurements on a 3 T MRI system.