J Korean Soc Magn Reson Med.  2012 Apr;16(1):6-15. 10.13104/jksmrm.2012.16.1.6.

Background Gradient Correction using Excitation Pulse Profile for Fat and T2* Quantification in 2D Multi-Slice Liver Imaging

• Nam Y
• Kim H
• Zho SY
• Kim DH

• KMID: 2099832
• DOI: http://doi.org/10.13104/jksmrm.2012.16.1.6

Abstract

PURPOSE
The objective of this study was to develop background gradient correction method using excitation pulse profile compensation for accurate fat and T2* quantification in the liver.
MATERIALS AND METHODS
In liver imaging using gradient echo, signal decay induced by linear background gradient is weighted by an excitation pulse profile and therefore hinders accurate quantification of T2* and fat. To correct this, a linear background gradient in the slice-selection direction was estimated from a B0 field map and signal decays were corrected using the excitation pulse profile. Improved estimation of fat fraction and T2* from the corrected data were demonstrated by phantom and in vivo experiments at 3 Tesla magnetic field.
RESULTS
After correction, in the phantom experiments, the estimated T2* and fat fractions were changed close to that of a well-shimmed condition while, for in vivo experiments, the background gradients were estimated to be up to approximately 120 microT/m with increased homogeneity in T2* and fat fractions obtained.
CONCLUSION
The background gradient correction method using excitation pulse profile can reduce the effect of macroscopic field inhomogeneity in signal decay and can be applied for simultaneous fat and iron quantification in 2D gradient echo liver imaging.

Keyword

Fat quantification; T2* measurement; IDEAL; field inhomogeneity; pulse profile; liver imaging

MeSH Terms

Compensation and Redress
Iron
Liver
Magnetics
Magnets
Iron