Design and application of combined 8-channel transmit and 10-channel receive arrays and radiofrequency shimming for 7-t shoulder magnetic resonance imaging

Ryan Brown, Cem Murat Deniz, Bei Zhang, Gregory Chang, Daniel K. Sodickson, Graham C. Wiggins

    Research output: Contribution to journalArticle

    Abstract

    OBJECTIVE: The objective of the study was to investigate the feasibility of 7-T shoulder magnetic resonance imaging by developing transmit and receive radiofrequency (RF) coil arrays and exploring RF shim methods. MATERIALS AND METHODS: A mechanically flexible 8-channel transmit array and an anatomically conformable 10-channel receive array were designed and implemented. The transmit performance of various RF shim methods was assessed through local flip angle measurements in the right and left shoulders of 6 subjects. The receive performance was assessed through signal-to-noise ratio measurements using the developed 7-T coil and a baseline commercial 3-T coil. RESULTS: The 7-T transmit array driven with phase-coherent RF shim weights provided adequate B1 efficiency and uniformity for turbo spin echo shoulder imaging. B1 twisting that is characteristic of high-field loop coils necessitates distinct RF shim weights in the right and left shoulders. The 7-T receive array provided a 2-fold signal-to-noise ratio improvement over the 3-T array in the deep articular shoulder cartilage. CONCLUSIONS: Shoulder imaging at 7-T is feasible with a custom transmit/receive array either in a single-channel transmit mode with a fixed RF shim or in a parallel transmit mode with a subject-specific RF shim.

    Original languageEnglish (US)
    Pages (from-to)35-47
    Number of pages13
    JournalInvestigative Radiology
    Volume49
    Issue number1
    DOIs
    StatePublished - Jan 1 2014

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    Keywords

    • RF coil array
    • RF shimming
    • high-field MRI
    • parallel transmission
    • shoulder

    ASJC Scopus subject areas

    • Radiology Nuclear Medicine and imaging

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