Optimizing the intrinsic signal-to-noise ratio of MRI strip detectors

Ananda Kumar, Paul A. Bottomley

Research output: Contribution to journalArticlepeer-review

Abstract

An MRI defector is formed from a conducting strip separated by a dielectric substrate from a ground plane, and tuned to a quarter-wavelength. By distributing discrete tuning elements along the strip, the geometric design may be adjusted to optimize the signal-to-noise ratio (SNR) for a given application. Here a numerical electromagnetic (EM) method of moments (MoM) is applied to determine the length, width, substrate thickness, dielectric constant, and number of tuning elements that yield the best intrinsic SNR (ISNR) of the strip detector at 1.5 Tesla. The central question of how strip performance compares with that of a conventional optimized loop coil is also addressed. The numerical method is validated against the known ISNR performance of loop coils, and its ability to predict the tuning capacitances and performance of seven experimental strip detectors of varying length, width, substrate thickness, and dielectric constant. We find that strip detectors with low-dielectric constant, moderately thin-substrate, and length about 1.3 (±0.2) times the depth of interest perform best. The ISNR of strips is comparable to that of loops (i.e., higher close to the detector but lower at depth). The SNR improves with two inherently-decoupled strips, whose sensitivity profile is well-suited to parallel MRI. The findings are summarized as design "rules of thumb."

Original languageEnglish (US)
Pages (from-to)157-166
Number of pages10
JournalMagnetic resonance in medicine
Volume56
Issue number1
DOIs
StatePublished - Jul 2006

Keywords

  • Detectors
  • MRI coils
  • Optimization
  • Phased-array
  • Signal-to-noise ratio

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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