Water and fat are the two predominant sources of signal for in vivo MRI. Because fat is
omnipresent in many parts of our body and because fat appears bright in many types of
basic MR images, it is often essential to be able to successfully suppress the fat signal.
Chemical shift selective saturation (CHESS) and short-tau inversion recovery (STIR)
are the two well-known techniques for this purpose. Despite their widespread use and
success, CHESS and STIR have fundamental limitations and as a consequence, poor
fat suppression is one of the most frequently-encountered image quality issues in
clinical practice. Further, it is difficult to implement the CHESS or STIR-based
techniques for some emerging applications such as fast dynamic imaging.
Another MRI technique for managing fat that has gained increasing clinical use only in
the last few years was first published by Tom Dixon in 1984. The original idea of the socalled Dixon techniques is to collect two images that have water and fat signals inphase and 180o out-of-phase, respectively. These two images can be added and
subtracted to yield a “water-only” image and a “fat-only” image. Thus, the Dixon
techniques have the potential for simultaneous fat suppression and fat quantification.
Additionally, it was recognized and is now demonstrated that the Dixon techniques can
be made highly insensitive to magnetic field inhomogeneity and highly SNR and scan
time efficient.
In this talk, I will provide an overview of some major development of the techniques for
managing fat in MRI. I will focus particularly on the physical basis as well as the
respective pros and cons of the different fat management techniques in MRI.
Learning Objectives:
1. Understand the physical basis and advantages and disadvantages of several
major fat management techniques in MRI
2. Understand some major issues and technical development of the Dixon
techniques for water and fat imaging
3. Understand some remaining challenges and future opportunities for fat
imaging and applications by MRI