SEPARATION OF FAT AND WATER IN FAST SPIN-ECHO MR-IMAGING WITH THE 3-POINT DIXON TECHNIQUE

A method for suppressing fat in fast spin-echo imaging with the three- point Dixon technique is described. The method differs from the three- point Dixon method used in conventional spin-echo imaging in that the readout gradient instead of a radio-frequency pulse is shifted. This m ethod preserves the Carr-Purcell-Meiboom-Gill nature of the fast spin- echo sequence and hence is less sensitive to magnetic field inhomogene ities and resonance frequency mistuning. As in the original three-poin t Dixon technique used in conventional spin-echo imaging, three acquis itions are required to estimate the field inhomogeneity and completely separate fat and water. The extra time required is not excessive cons idering that the fast spin-echo method is frequently applied with mult iple signal acquisition. Also, this technique achieves an expected sig nal-to-noise ratio comparable to 2.67 signal acquisitions, which is ap proximately 94% of the signal-to-noise ratio obtained with three signa l acquisitions. The method is demonstrated with applications to phanto ms and a human volunteer.