Concurrent J-evolving refocusing pulses

Sebastian Ehni; Martin R M Koos; Tony Reinsperger; Jens D Haller; David L Goodwin; Burkhard Luy

doi:10.1016/j.jmr.2022.107152

Concurrent J-evolving refocusing pulses

J Magn Reson. 2022 Mar:336:107152. doi: 10.1016/j.jmr.2022.107152. Epub 2022 Feb 1.

Authors

Sebastian Ehni¹, Martin R M Koos², Tony Reinsperger³, Jens D Haller⁴, David L Goodwin⁵, Burkhard Luy⁶

Affiliations

¹ Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Bruker Biospin GmbH, Fällanden 8117, Switzerland.
² Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Pfizer Inc., Groton, CT 06340, USA; Department of Chemistry, Carnegie Mellon University, Pittsburgh, USA.
³ Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Bruker Biospin GmbH, Ettlingen 76275, Germany.
⁴ Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
⁵ Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK. Electronic address: [email protected].
⁶ Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany. Electronic address: [email protected].

PMID: 35189510
DOI: 10.1016/j.jmr.2022.107152

Abstract

Conventional refocusing pulses are optimised for a single spin without considering any type of coupling. However, despite the fact that most couplings will result in undesired distortions, refocusing in delay-pulse-delay-type sequences with desired heteronuclear coherence transfer might be enhanced considerably by including coupling evolution into pulse design. We provide a proof of principle study for a Hydrogen-Carbon refocusing pulse sandwich with inherent J-evolution following the previously reported ICEBERG-principle with improved performance in terms of refocusing performance and/or overall effective coherence transfer time. Pulses are optimised using optimal control theory with a newly derived quality factor and z-controls as an efficient tool to speed up calculations. Pulses are characterised in theory and experiment and compared to conventional concurrent refocusing pulses, clearly showing an improvement for the J-evolving pulse sandwich. As a side-product, also efficient J-compensated resfocusing pulse sandwiches - termed BUBU pulses following the nomenclature of previous J-compensated BUBI and BEBE^tr pulse sandwiches - have been optimised.

Keywords: Broadband pulses; J-Evolution; Optimal control; Refocusing; Shaped pulses.

Publication types

Research Support, Non-U.S. Gov't