Fat Suppression

Two major methods we use to suppress fat signal and preserve water signal are:

Chem Sat (based on difference in resonance frequency)

and

STIR (base on difference in T1 relaxation time)

One potential issue is that if there is enhancement of pathology with T1 shortening, the enhancing pathology may be suppressed as well. See reference below from Weinreb et. al. Nice phantom study and clinical examples proving this point.Jeff Weinreb was an attending at SLR briefly in the1980s before going to NYU.

A third technique is known as the Dixon technique (also taking advantage of the difference in resonance frequency of fat and water). In one form of this technique (2-point Dixon), images are acquired in phase and out of phase. Calculated water and fat images are generated as well. See discussion of in-phase/out of phase.

References:

http://www.revisemri.com/blog/2010/fat-suppression/

Weinreb Article

http://www.ajronline.org/doi/pdf/10.2214/ajr.166.3.8623620

http://www.healthcare.siemens.com/siemens_hwem-hwem_ssxa_websites-context-root/wcm/idc/siemens_hwem-hwem_ssxa_websites-context-root/wcm/idc/groups/public/@global/@imaging/@mri/documents/download/mdaw/mtmz/~edisp/fat_suppression_techniques-00033824.pdf

Selective excitation animation:

http://www.imaios.com/en/e-Courses/e-MRI/Improving-MRI-contrast-Imaging-water-and-fat/selective-excitation

http://cds.ismrm.org/protected/09MProceedings/files/Tues%20C36_01%20Cameron.pdf