Resolution enhancement in single-shot imaging using simultaneous acquisition of spatial harmonics (SMASH)

Mark A. Griswold, P. M. Jakob, Q. Chen, J. W. Goldfarb, W. J. Manning, R. R. Edelman, D. K. Sodickson

    Research output: Contribution to journalArticle

    Abstract

    Spatial resolution in single-shot imaging is limited by signal attenuation due to relaxation of transverse magnetization. This effect can be reduced by minimizing acquisition times through the use of short interecho spacings. However, the minimum interecho spacing is constrained by limits on gradient switching rates, radiofrequency (RF) power deposition and RF pulse length. Recently, simultaneous acquisition of spatial harmonics (SMASH) has been introduced as a method to acquire magnetic resonance images at increased speeds using a reduced number of phase-encoding gradient steps by extracting spatial information contained in an RF coil array. In this study, it is shown that SMASH can be used to reduce the effects of relaxation, resulting in single-shot images with increased spatial resolution without increasing imaging time. After a brief theoretical discussion, two strategies to reduce signal attenuation and increase spatial resolution in single-shot imaging are introduced and their performance is evaluated in phantom studies. In vivo single-shot echoplanar imaging (EPI), BURST, and half-Fourier single-shot turbo spin-echo (HASTE) images are then presented demonstrating the practical implementation of these resolution enhancement strategies. Images acquired with SMASH show increased spatial resolution and improved image quality when compared with images obtained with the conventional acquisitions. The general principles presented for imaging with SMASH can also be applied to other partially parallel imaging techniques.

    Original languageEnglish (US)
    Pages (from-to)1236-1245
    Number of pages10
    JournalMagnetic resonance in medicine
    Volume41
    Issue number6
    DOIs
    StatePublished - 1999

    Keywords

    • Magnetic resonance imaging
    • Single-shot imaging
    • Spatial resolution
    • Spin relaxation

    ASJC Scopus subject areas

    • Radiology Nuclear Medicine and imaging

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