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Quantification and correction of respiration induced dynamic field map changes in fMRI using 3D single shot techniques

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Abstract

Purpose

Respiration induced dynamic field map changes in the brain are quantified and the influence on the magnitude signal (physiological noise) is investigated. Dynamic off-resonance correction allows to reduce the signal fluctuations overlaying the blood oxygenation level dependent signal in math formula-weighted functional imaging.

Theory and Methods

A single-shot whole brain imaging technique with 100 ms temporal resolution was used to measure dynamic off-resonance maps that were calculated from the incremental changes of the image phase. These off-resonance maps are then used to dynamically update the off-resonance corrected reconstruction.

Results

A global resonance offset and a pronounced gradient in head–foot direction were identified as the main components of the change during a respiration cycle. On average, correction for these fluctuations decreases the magnitude fluctuations by around 30%.

Conclusion

Single shot 3D imaging allows for a robust quantification of dynamic off-resonance changes in the brain. Correction for these fluctuations removes the physiological noise component associated with dynamic point spread function changes. Magn Reson Med 71:1093–1102, 2014. © 2013 Wiley Periodicals, Inc.

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