Improved Fat/Water Separation

  • The majority of applications, particularly in the body imaging, require the need to acquire images with and without fat suppression for enhanced visualization of various pathologies. Fat suppression is challenging at higher field strengths, e.g. 3 T, due to increased B0 inhomogeneities.
  • We are currently developing chemical-shift (or Dixon) based techniques for improved fat suppression, even in the presence of B0 inhomogeneities. Particularly, we are developing enhanced fast/turbo spin echo (FSE/TSE) based techniques using multi-echo acquisition, where the in-phase (IP) and out-of-phase (OP) echoes required for Dixon processing are acquired in the same repetition, without increasing the scan times.
  • Brachial Plexus Imaging: Our initial target has been to improve the conspicuity of nerves in the neck and shoulders (i.e., Brachial Plexus), where the B0 inhomogeneities are significant due to the air/tissue/lung interface. (Wang X et. al. Radiology 2017)

Maximum intensity projection (MIP) of the brachial plexus showing enhanced visualization of the nerves from the spinal cord to the shoulders and the upper arms with uniform fat/water separation.

  • Abdominal Imaging: We further extended this approach to acquire abdominal images in a single shot turbo spin echo (SShTSE), which is routinely used due to its robustness to motion artifacts. This approach provides perfectly co-registered images with and without fat suppression along with fat-only images in the same acquisition (Wang X et. al. MagnReson. Med. 2021 – in press).

Axial SShTSE T2-weighted images of a 61-year-old healthy volunteer acquired without and with fat suppression using SPAIR (top row). The corresponding in-phase, water-only, and fat-only images (bottom row) reconstructed from the SShTSE-mDixon acquisition show uniform fat suppression. The arrows show incomplete suppression on SShTSE-SPAIR image.