A broadband phased-array system for direct phosphorus and sodium metabolic MRI on a clinical scanner

Ray F. Lee, Randy Giaquinto, Chris Constantinides, Steven Souza, Robert G. Weiss, Paul A. Bottomley

Research output: Contribution to journalArticle

Abstract

Despite their proven gains in signal-to-noise ratio and field-of-view for routine clinical MRI, phased-array detection systems are currently unavailable for nuclei other than protons (1H). A broadband phased-array system was designed and built to convert the 1H transmitter signal to the non-1H frequency for excitation and to convert non-1H phased-array MRI signals to the 1H frequency for presentation to the narrowband 1H receivers of a clinical whole-body 1.5 T MRI system. With this system, the scanner operates at the 1H frequency, whereas phasedarray MRI occurs at the frequency of the other nucleus. Pulse sequences were developed for direct phased-array sodium (23Na) and phosphorus (31P) MRI of high-energy phosphates using chemical selective imaging, thereby avoiding the complex processing and reconstruction required for phased-array magnetic resonance spectroscopy data. Flexible 4-channel 31P and 23Na phased-arrays were built and the entire system tested in phantom and human studies. The array produced a signal-to-noise ratio improvement of 20% relative to the best- positioned single coil, but gains of 300-400% were realized in many voxels located outside the effective field-of-view of the single coil. Cardiac phosphorus and sodium MRI were obtained in 6-13 min with 16 and 0.5 mL resolution, respectively. Lower resolution human cardiac 23Na MRI were obtained in as little as 4 sec. The system provides a practical approach to realizing the advantages of phased-arrays for nuclei other than 1H, and imaging metabolites directly. (C) 2000 Wiley-Liss, Inc.

Original languageEnglish (US)
Pages (from-to)269-277
Number of pages9
JournalMagnetic resonance in medicine
Volume43
Issue number2
DOIs
StatePublished - Feb 12 2000

Keywords

  • Heart
  • High-energy phosphate
  • Metabolic imaging
  • Phased-array
  • Sodium

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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