Saturation Recovery Fast Gradient Echo: Perfusion

Imaging Sequence Type:

  • Saturation Recovery Prepared FSPGR (GE), FLASH (Siemens), T1 FFE (Philips), Field Echo (Toshiba)
  • Images are typically generated over several heartbeats during a breathhold

Acquisition Mode: Multi slice, multiphase (i.e. cines at multiple slice locations showing first passage of a contrast bolus)

Image Contrast:

  • Bright blood (following gadolinium contrast)
  • T1-weighted
  • Alternative sequences that are sometimes used include
    • saturation recovery gradient-echo echo-planar imaging (EPI)
    • saturation recovery steady state free precession (SSFP)

Imaging Options: Parallel imaging is usually employed to improve image temporal resolution and spatial coverage: ASSET (GE), iPAT (Siemens), SENSE (Philips), SPEEDER (Toshiba)

Clinical Utility:

  • Perfusion imaging is usually performed during stress to assess for obstructive coronary artery disease.
  • A perfusion defect is identified as a region of decreased myocardial signal during the first pass contrast bolus (“dark spots are bad”). In the case shown above, the patient has a severe stenosis of the mid LAD which causes diminished perfusion to the midventricular anteroseptum and the apex.
  • The most common stress agents for MRI are vasodilators (e.g. adenosine or regadenoson)
  • Stress perfusion imaging is usually combined with either rest perfusion imaging or late gadolinium enhancement (LGE) imaging to distinguish coronary insufficiency from myocardial scar.
  • The patient is usually instructed to breath hold during image acquisition, although it is not absolutely essential.
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