System and SAR characterization in parallel RF transmission

Yudong Zhu, Leeor Alon, Cem M. Deniz, Ryan Brown, Daniel K. Sodickson

    Research output: Contribution to journalArticle

    Abstract

    The markedly increased degrees of freedom introduced by parallel radiofrequency transmission presents both opportunities and challenges for specific absorption rate (SAR) management. On one hand they enable E-field tailoring and SAR reduction while facilitating excitation profile control. On other hand they increase the complexity of SAR behavior and the risk of inadvertently exacerbating SAR by improper design or playout of radiofrequency pulses. The substantial subject-dependency of SAR in high field magnetic resonance can be a compounding factor. Building upon a linear system concept and a calibration scheme involving a finite number of in situ measurements, this work establishes a clinically applicable method for characterizing global SAR behavior as well as channel-by-channel power transmission. The method offers a unique capability of predicting, for any excitation, the SAR and power consequences that are specific to the subject to be scanned and the MRI hardware. The method was validated in simulation and experimental studies, showing promise as the foundation to a prospective paradigm where power and SAR are not only monitored but, through prediction-guided optimization, proactively managed.

    Original languageEnglish (US)
    Pages (from-to)1367-1378
    Number of pages12
    JournalMagnetic resonance in medicine
    Volume67
    Issue number5
    DOIs
    StatePublished - May 2012

    Keywords

    • B1 shimming
    • RF coil
    • RF power
    • RF safety
    • RF shimming
    • SAR
    • high field MR
    • linear system
    • parallel RF transmission
    • system calibration

    ASJC Scopus subject areas

    • Radiology Nuclear Medicine and imaging

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  • Cite this

    Zhu, Y., Alon, L., Deniz, C. M., Brown, R., & Sodickson, D. K. (2012). System and SAR characterization in parallel RF transmission. Magnetic resonance in medicine, 67(5), 1367-1378. https://doi.org/10.1002/mrm.23126