TROMBONE: T1-relaxation-oblivious mapping of transmit radio-frequency field (B1) for MRI at high magnetic fields

Roman Fleysher, Lazar Fleysher, Matilde Inglese, Daniel Sodickson

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Fast, 3D radio-frequency transmit field (B1) mapping is important for parallel transmission, spatially selective pulse design and quantitative MRI applications. It has been shown that actual flip angle imaging - two interleaved spoiled gradient recalled echo images acquired in steady state with two very short time delays (TR1, TR2) - is an attractive method of B1 mapping. Herein, we describe the TROMBONE method that efficiently integrates actual flip angle imaging with EPI imaging, alleviates very short TR requirement of actual flip angle imaging and through their synergy yields up to 16 times higher precision in B1 estimation in the same experimental time. High precision of TROMBONE can be traded for faster scans. The map of B1 reconstructed from the ratio of intensities of two images is insensitive to longitudinal relaxation time (T 1) in the physiologically relevant range. A table of the optimal acquisition protocol parameters for various target experimental conditions is provided.

    Original languageEnglish (US)
    Pages (from-to)483-491
    Number of pages9
    JournalMagnetic resonance in medicine
    Volume66
    Issue number2
    DOIs
    StatePublished - Aug 2011

    Keywords

    • RF inhomogeneity
    • actual flip angle imaging
    • fast volumetric imaging
    • high-field MRI
    • optimization methods
    • parallel transmission
    • quantitative MRI

    ASJC Scopus subject areas

    • Radiology Nuclear Medicine and imaging

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