System identification and signal processing for PID control of B0 shim systems in ultra-high field magnetic resonance applications

Yu Chun Chang, Nikolai Avdievich, Anke Henning

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Magnetic resonance (MR) scanners are important tools in medical diagnostics and in many areas of neuroscience. MR technology is moving towards ultra-high field (UHF) 7T and 9.4T scanners which provide more signal intensity. However they also suffer from inhomogeneity of the static (B0) magnetic field which can lead to artifacts and uninterpretable data. B0 shimming is a technique used to reduce inhomogeneities but most MR scanners use static shim settings for the duration of the experiment. Dynamic shim updating (DSU) updates the shim in real-time while the scan is in process and can hence reduce any fluctuations in B0 field which may arise due to patient breathing, mechanical vibrations and soforth. However DSU is currently very slow and if we intend to increase the update rate then control theory needs to be applied. This paper presents an application of basic system identification and signal processing in the context of MR systems for DSU. Although system identification of these systems has been done before, they are non-parametric frequency domain approaches. These systems can be modelled as linear multivariable systems.

Original languageEnglish (US)
Title of host publication19th IFAC World Congress IFAC 2014, Proceedings
EditorsXiaohua Xia, Edward Boje
PublisherIFAC Secretariat
Pages7517-7522
Number of pages6
ISBN (Electronic)9783902823625
Publication statusPublished - Jan 1 2014
Externally publishedYes
Event19th IFAC World Congress on International Federation of Automatic Control, IFAC 2014 - Cape Town, South Africa
Duration: Aug 24 2014Aug 29 2014

Publication series

NameIFAC Proceedings Volumes (IFAC-PapersOnline)
Volume19
ISSN (Print)1474-6670

Conference

Conference19th IFAC World Congress on International Federation of Automatic Control, IFAC 2014
CountrySouth Africa
CityCape Town
Period8/24/148/29/14

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Keywords

  • Gyromagnetic ratios
  • Hurwitz criterion
  • Medical systems
  • Parameter optimization
  • Phase-locked loop
  • PID controllers
  • Process identification
  • Smoothing filters

ASJC Scopus subject areas

  • Control and Systems Engineering

Cite this

Chang, Y. C., Avdievich, N., & Henning, A. (2014). System identification and signal processing for PID control of B0 shim systems in ultra-high field magnetic resonance applications. In X. Xia, & E. Boje (Eds.), 19th IFAC World Congress IFAC 2014, Proceedings (pp. 7517-7522). (IFAC Proceedings Volumes (IFAC-PapersOnline); Vol. 19). IFAC Secretariat.