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Utility of real-time field control in T2*-Weighted head MRI at 7T


Duerst, Yolanda; Wilm, Bertram J; Wyss, Michael; Dietrich, Benjamin E; Gross, Simon; Schmid, Thomas; Brunner, David O; Pruessmann, Klaas P (2016). Utility of real-time field control in T2*-Weighted head MRI at 7T. Magnetic Resonance in Medicine, 76(2):430-439.

Abstract

PURPOSE: Real-time field control can serve to reduce respiratory field perturbations during T2 * imaging at high fields. This work investigates the effectiveness of this approach in relation to key variables such as patient physique, breathing patterns, slice location, and the choice of sequence.
METHODS: To cover variation in physical constitution and breathing behavior, volunteers with a wide range of body-mass-indices were asked to breathe either normally or deeply during T2 *-weighted image acquisition at 7T. Ensuing field fluctuation was countered by real-time field control or merely recorded in reference experiments. The impact of the control system on image quality was assessed by classifying and grading artifacts related to field fluctuation.
RESULTS: The amplitude of respiratory field changes and related artifacts were generally stronger for subjects with higher body-mass-index and for lower slices. Field control was found effective at mitigating all five types of artifacts that were studied. Overall image quality was systematically improved. Residual artifacts in low slices are attributed to insufficient spatial order of the control system.
CONCLUSION: Real-time field control was found to be a robust means of countering respiratory field perturbations in variable conditions encountered in high-field brain imaging. Reducing net fluctuation, it generally expands the feasibility of high-field T2 * imaging toward challenging patients and brain regions. Magn Reson Med, 2015. © 2015 Wiley Periodicals, Inc.

Abstract

PURPOSE: Real-time field control can serve to reduce respiratory field perturbations during T2 * imaging at high fields. This work investigates the effectiveness of this approach in relation to key variables such as patient physique, breathing patterns, slice location, and the choice of sequence.
METHODS: To cover variation in physical constitution and breathing behavior, volunteers with a wide range of body-mass-indices were asked to breathe either normally or deeply during T2 *-weighted image acquisition at 7T. Ensuing field fluctuation was countered by real-time field control or merely recorded in reference experiments. The impact of the control system on image quality was assessed by classifying and grading artifacts related to field fluctuation.
RESULTS: The amplitude of respiratory field changes and related artifacts were generally stronger for subjects with higher body-mass-index and for lower slices. Field control was found effective at mitigating all five types of artifacts that were studied. Overall image quality was systematically improved. Residual artifacts in low slices are attributed to insufficient spatial order of the control system.
CONCLUSION: Real-time field control was found to be a robust means of countering respiratory field perturbations in variable conditions encountered in high-field brain imaging. Reducing net fluctuation, it generally expands the feasibility of high-field T2 * imaging toward challenging patients and brain regions. Magn Reson Med, 2015. © 2015 Wiley Periodicals, Inc.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Biomedical Engineering
Dewey Decimal Classification:170 Ethics
610 Medicine & health
Uncontrolled Keywords:7 Tesla; NMR field probes; T2*-weighted imaging; dynamic shimming; field camera; field control
Language:English
Date:2016
Deposited On:03 Feb 2016 15:07
Last Modified:15 Jul 2016 01:01
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:0740-3194
Publisher DOI:https://doi.org/10.1002/mrm.25838
PubMed ID:26307944

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