Managing Fat in MRI: A Technical Perspective
J Ma1, (1) UT MD Anderson Cancer Center, HOUSTON, TXTH-A-218-1 Thursday 8:00:00 AM - 8:55:00 AM Room: 218
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 so-called Dixon techniques is to collect two images that have water and fat signals in-phase 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.
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