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Utility of real‐time field control in T 2 *‐Weighted head MRI at 7T
Author(s) -
Duerst Yolanda,
Wilm Bertram J.,
Wyss Michael,
Dietrich Benjamin E.,
Gross Simon,
Schmid Thomas,
Brunner David O.,
Pruessmann Klaas P.
Publication year - 2016
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.25838
Subject(s) - computer science , image quality , field (mathematics) , residual , artificial intelligence , mathematics , algorithm , image (mathematics) , pure mathematics
Purpose Real‐time field control can serve to reduce respiratory field perturbations during T 2 * 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 T 2 *‐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 T 2 * imaging toward challenging patients and brain regions. Magn Reson Med 76:430–439, 2016. © 2015 Wiley Periodicals, Inc.