Motion-sensitized driven equilibrium for blood-suppressed T2* mapping

J Magn Reson Imaging. 2011 Sep;34(3):702-9. doi: 10.1002/jmri.22664. Epub 2011 Jul 18.

Abstract

Purpose: To combine a motion-sensitized driven equilibrium (MSDE) preparation with a multi-echo spoiled gradient-echo sequence (SPGR) to suppress the blood signal intensity in T2* mapping of carotid plaques and liver.

Materials and methods: The analytical solution of the Bloch equations for the multi-echo SPGR sequence, with and without the MSDE preparation, was calculated to optimize sequence parameters. The sequence was implemented at 3 Tesla and T2* maps of carotid plaques and liver were first optimized for blood suppression, and then acquired from five healthy livers and six subjects with ultrasound-identified carotid plaques.

Results: Simulations and experimental data showed that the flip angle that gives maximal signal (Ernst angle) in the MSDE-SPGR was greatly increased from that of pure SPGR. Robust blood suppression was obtained in the T2* maps of carotid plaques and liver, requiring suppression at a field of speed (FOS) of 30 cm/s in both the carotids and liver.

Conclusion: MSDE provides a means to suppress the blood signal intensity in SPGR sequences. Tissue T2* maps can be obtained without the confounding effects originating from blood vessels.

MeSH terms

  • Algorithms
  • Artifacts*
  • Carotid Stenosis / blood*
  • Carotid Stenosis / pathology*
  • Humans
  • Image Enhancement / methods
  • Image Interpretation, Computer-Assisted / methods*
  • Liver / anatomy & histology
  • Liver / blood supply*
  • Magnetic Resonance Imaging / methods*
  • Motion
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Subtraction Technique*