Optimization of two-dimensional spatially selective NMR pulses by simulated annealing

C. J. Hardy, P. A. Bottomley, M. O'Donnell, P. Roemer

Research output: Contribution to journalArticlepeer-review

Abstract

Two-dimensional spatial localization can be achieved with a single NMR inverting or refocusing pulse, by applying the RF pulse in the presence of a net magnetic field gradient which reorients through two dimensions during the course of the pulse. Simple rotating ("ρ{variant}") pulses of this type, however, have the disadvantage of producing ringing outside the central selected volume of the 2D sensitivity profile. In order to eliminate this ringing, a simulated annealing technique has been used to simultaneously optimize the RF and gradient waveforms, producing pulses which leave the NMR signal localized to a well-defined cylinder. These pulses have been implemented on a whole-body NMR system to produce restricted field-of-view images of agarose disk phantoms and of the head. Applications of optimized ρ{variant} pulses include localization in 31P spectroscopy and elimination of aliasing artifacts in NMR imaging.

Original languageEnglish (US)
Pages (from-to)233-250
Number of pages18
JournalJournal of Magnetic Resonance (1969)
Volume77
Issue number2
DOIs
StatePublished - Apr 1988
Externally publishedYes

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