Dephased FLAPS for improved visualization of susceptibility-shifted passive devices for real-time interventional MRI

Phys Med Biol. 2007 Jul 7;52(13):N277-86. doi: 10.1088/0031-9155/52/13/N01. Epub 2007 May 25.

Abstract

Recently, balanced steady-state free precession (SSFP) magnetic resonance imaging at small flip angles (i.e. FLAPS imaging) has been shown to preferentially enhance the visibility of spins residing near susceptibility-shifted media by exploiting the unique spectral response of SSFP signals. Nevertheless, the use of FLAPS imaging to visualize passive, susceptibility-shifted devices within thick slices is complicated by partial volume effects that reduce the conspicuity of the devices. In this work, dephased FLAPS (dFLAPS), a variation of the FLAPS method with dephasing gradients applied in the slice direction, is presented as a method for improving the contrast of susceptibility-shifted interventional devices in thick-slice magnetic resonance images by suppressing signal from on-resonant spins. In comparison to FLAPS imaging, results demonstrate that dFLAPS imaging of thick, projection-like slices improves the contrast of susceptibility-shifted devices relative to background signal with no increase in acquisition time.

MeSH terms

  • Animals
  • Aorta, Thoracic / pathology
  • Biopsy, Needle
  • Cattle
  • Electromagnetic Fields
  • Humans
  • Liver / pathology
  • Magnetic Resonance Imaging, Interventional / methods*
  • Models, Statistical
  • Models, Theoretical
  • Myocardium / pathology
  • Phantoms, Imaging
  • Stents
  • Time Factors
  • Whole Body Imaging