Reduced field of view MRI with rapid, B 1-robust outer volume suppression

Travis B. Smith, Krishna S. Nayak

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

MRI scans are inefficient when the size of the anatomy under investigation is small relative to the subject's full extent. The field of view must be expanded, and acquisition times accordingly prolonged. Shorter scans are feasible with reduced field of view imaging (rFOV) using outer volume suppression (OVS), a magnetization preparation sequence that attenuates signal outside a region of interest (ROI). This work presents a new OVS sequence with a cylindrical ROI, short duration, and improved tolerance for B 1 + inhomogeneity. The sequence consists of a nonselective adiabatic tipdown pulse, which provides B 1 +-robust signal suppression, and a fast 2D spiral cylindrical tipback pulse. Analysis of the Bloch equations with transverse initial magnetization reveals a conjugate symmetric constraint for tipback pulses with small flip angles. This property is exploited to achieve two-shot performance from the single-shot tipback pulse. The OVS sequence is validated in phantoms and in vivo with multislice spiral imaging at 3 T. The relative signal-to-noise ratio efficiency of the proposed sequence was 98% in a phantom and 75-90% in vivo. The effectiveness is demonstrated with cardiovascular rFOV imaging, which exhibits improved resolution and reduced artifacts compared to conventional, full field of view imaging.

Original languageEnglish (US)
Pages (from-to)1316-1323
Number of pages8
JournalMagnetic Resonance in Medicine
Volume67
Issue number5
DOIs
StatePublished - May 1 2012

Keywords

  • RF pulse design
  • outer volume suppression
  • reduced field of view imaging
  • spiral imaging

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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