PURPOSE: MR image formation and interpretation relies on highly accurate dynamic magnetic fields of high fidelity. A range of mechanisms still limit magnetic field fidelity, including magnet drifts, eddy currents, and finite linearity and stability of power amplifiers used to drive gradient and shim coils. Addressing remaining errors by means of hardware, sequence, or signal processing optimizations, calls for immediate observation by magnetic field monitoring. The present work presents a stand-alone monitoring system delivering insight into such field imperfections for MR sequence and system analysis. METHODS: A flexible NMR field probe-based stand-alone monitoring system, built on a software-defined-radio approach, is introduced and used to sense field dynamics up to third-order in space in a selection of situations with different time scales. RESULTS: Highly sensitive trajectories are measured and successfully used for image reconstruction. Further field perturbations due to mechanical oscillations and thermal field drifts following demanding gradient use and external interferences are studied. CONCLUSION: A flexible and versatile monitoring system is presented, delivering camera-like access to otherwise hardly accessible field dynamics with nanotesla resolution. Its stand-alone nature enables field analysis even during unknown MR system states.
PURPOSE: MR image formation and interpretation relies on highly accurate dynamic magnetic fields of high fidelity. A range of mechanisms still limit magnetic field fidelity, including magnet drifts, eddy currents, and finite linearity and stability of power amplifiers used to drive gradient and shim coils. Addressing remaining errors by means of hardware, sequence, or signal processing optimizations, calls for immediate observation by magnetic field monitoring. The present work presents a stand-alone monitoring system delivering insight into such field imperfections for MR sequence and system analysis. METHODS: A flexible NMR field probe-based stand-alone monitoring system, built on a software-defined-radio approach, is introduced and used to sense field dynamics up to third-order in space in a selection of situations with different time scales. RESULTS: Highly sensitive trajectories are measured and successfully used for image reconstruction. Further field perturbations due to mechanical oscillations and thermal field drifts following demanding gradient use and external interferences are studied. CONCLUSION: A flexible and versatile monitoring system is presented, delivering camera-like access to otherwise hardly accessible field dynamics with nanotesla resolution. Its stand-alone nature enables field analysis even during unknown MR system states.
Keywords:
field camera; field drifts; gradient vibrations; gradients; hardware; magnetic field monitoring; monitoring; scanner cool-down; stand-alone; trajectories
Authors: Yunhong Shu; Shengzhen Tao; Joshua D Trzasko; John Huston; Paul T Weavers; Matt A Bernstein Journal: Magn Reson Med Date: 2017-08-21 Impact factor: 4.668
Authors: Susie Y Huang; Thomas Witzel; Boris Keil; Alina Scholz; Mathias Davids; Peter Dietz; Elmar Rummert; Rebecca Ramb; John E Kirsch; Anastasia Yendiki; Qiuyun Fan; Qiyuan Tian; Gabriel Ramos-Llordén; Hong-Hsi Lee; Aapo Nummenmaa; Berkin Bilgic; Kawin Setsompop; Fuyixue Wang; Alexandru V Avram; Michal Komlosh; Dan Benjamini; Kulam Najmudeen Magdoom; Sudhir Pathak; Walter Schneider; Dmitry S Novikov; Els Fieremans; Slimane Tounekti; Choukri Mekkaoui; Jean Augustinack; Daniel Berger; Alexander Shapson-Coe; Jeff Lichtman; Peter J Basser; Lawrence L Wald; Bruce R Rosen Journal: Neuroimage Date: 2021-08-28 Impact factor: 7.400
Authors: Qiuyun Fan; Cornelius Eichner; Maryam Afzali; Lars Mueller; Chantal M W Tax; Mathias Davids; Mirsad Mahmutovic; Boris Keil; Berkin Bilgic; Kawin Setsompop; Hong-Hsi Lee; Qiyuan Tian; Chiara Maffei; Gabriel Ramos-Llordén; Aapo Nummenmaa; Thomas Witzel; Anastasia Yendiki; Yi-Qiao Song; Chu-Chung Huang; Ching-Po Lin; Nikolaus Weiskopf; Alfred Anwander; Derek K Jones; Bruce R Rosen; Lawrence L Wald; Susie Y Huang Journal: Neuroimage Date: 2022-02-23 Impact factor: 7.400
Authors: Daehun Kang; Uten Yarach; Myung-Ho In; Erin M Gray; Joshua D Trzasko; Hang Joon Jo; Yunhong Shu; John Huston; Matt A Bernstein Journal: Magn Reson Med Date: 2019-12-04 Impact factor: 4.668
Authors: Ovidiu C Andronesi; Pallab K Bhattacharyya; Wolfgang Bogner; In-Young Choi; Aaron T Hess; Phil Lee; Ernesta M Meintjes; M Dylan Tisdall; Maxim Zaitzev; André van der Kouwe Journal: NMR Biomed Date: 2020-07-20 Impact factor: 4.044
Authors: Romain Froidevaux; Markus Weiger; Manuela B Rösler; David O Brunner; Klaas P Pruessmann Journal: NMR Biomed Date: 2021-02-23 Impact factor: 4.044
Authors: Edwin Versteeg; Tijl A van der Velden; Carel C van Leeuwen; Martino Borgo; Erik R Huijing; Arjan D Hendriks; Jeroen Hendrikse; Dennis W J Klomp; Jeroen C W Siero Journal: NMR Biomed Date: 2021-02-22 Impact factor: 4.044