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Sodium imaging of human brain at 7 T with 15‐channel array coil
Author(s) -
Qian Yongxian,
Zhao Tiejun,
Wiggins Graham C.,
Wald Lawrence L.,
Zheng Hai,
Weimer Jonathan,
Boada Fernando E.
Publication year - 2012
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.24192
Subject(s) - electromagnetic coil , radiofrequency coil , signal to noise ratio (imaging) , noise (video) , phased array , scanner , optics , partial volume , sensitivity (control systems) , magnetic resonance imaging , pulse sequence , nuclear magnetic resonance , channel (broadcasting) , physics , acoustics , computer science , antenna (radio) , image (mathematics) , electronic engineering , artificial intelligence , telecommunications , medicine , radiology , quantum mechanics , engineering
Signal‐to‐noise ratio (SNR) is a major challenge to sodium magnetic resonance imaging. Phased array coils have been shown significantly improving SNR in proton imaging over volume coils. This study investigates SNR advantage of a 15‐channel array head coil (birdcage volume coil for transmit/receive and 15‐channel array insert for receive‐only) in sodium imaging at 7 T. Phantoms and healthy human brains were scanned on a whole‐body 7 T magnetic resonance imaging scanner using a customer‐developed pulse sequence with the twisted projection imaging trajectory. Noise‐only images were acquired with blanked radiofrequency excitations for noise measurement on a pixel basis. SNR was calculated on the root of sum‐of‐squares images. When compared with the volume coil, the 15‐channel array produced SNR more than doubled at the periphery and slightly increased at the center of the phantoms and human brains. Decorrelation of noise across channels of the array coil extended the SNR‐doubled region into deep area of the brain. The spatial modulation of element sensitivities on the sum‐of‐squares combined image was removed by performing self‐calibrated sensitivity encoding parallel image reconstruction and uniform image intensity across entire field of view was attained. The 15‐channel array coil is an efficient tool to substantially improve SNR in sodium imaging on human brain. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.