3D interleaved water and fat image acquisition with chemical-shift correction

A new technique, 3D interleaved water and fat image acquisition with chemical-shift correction (3-DIWFAC), was developed to acquire 3D water and fat images in a single acquisition time and to combine the water and fat images to produce chemical-shift-free images. A 3D gradient-recalled-echo (GRE) sequence was implemented with a 1-3-3-1 binomial Shinnar-Le Roux spatial-spectral excitation, and with interleaved phase-encoding lines that alternate between water and fat excitations separated by half TR. Water-only and fat-only images were then realigned to remove chemical shift artifacts. Results from phantoms and human subjects demonstrated that the image contrast was the same as in the regular GRE sequence. With the chemical shift corrected, the shadow artifacts often seen at water and fat boundaries were removed. Since this sequence simultaneously provides water-only images showing cartilage and bone lesions, and water-fat images that depict soft tissue anatomy, it may be clinically useful in musculoskeletal imaging. Magn Reson Med 44:322-330, 2000.