Lipid elimination with an echo‐shifting N/2‐ghost acquisition (LEENA) MRI

Abstract

Purpose The Dixon techniques provide uniform water-fat separation but require multiple image sets, which extend the overall acquisition time. Here, an alternative rapid single acquisition method, lipid elimination with an echo-shifting N/2-ghost acquisition (LEENA), was introduced. Methods The LEENA method utilized a fast imaging with steady-state free precession sequence to obtain a single k-space dataset in which successive k-space lines are acquired to allow the fat magnetization to precess 180°. The LEENA data were then unghosted using either image-domain (LEENA-S) or k-space domain (LEENA-G) parallel imaging techniques to reconstruct water-only and fat-only images. An off-resonance correction technique was incorporated to improve the uniformity of the water-fat separation. Results Uniform water-fat separation was achieved for both the LEENA-S and LEENA-G methods for phantom and human body and leg imaging applications at 1.5T and 3T The resultant water and fat images were qualitatively similar to conventional 2-point Dixon and fat-suppressed images. Conclusion The LEENA-S and LEENA-G methods provide uniform water and fat images from a single MRI acquisition. These straightforward methods can be adapted to 1.5T and 3T clinical MRI scanners and provide comparable fat/water separation with conventional 2-point Dixon and fat-suppression techniques.

Reducing SAR in 7T brain fMRI by circumventing fat suppression while removing the lipid signal through a parallel acquisition approach

“…Examples include the correction of ghost artifacts in EPI 26 and restricted FOV imaging 27 , 28 . Parallel acquisition has also been shown to improve the reconstruction in chemical shift imaging 29 and in lipid ghosts elimination 30 . The SENSE method has been successfully applied in hyperpolarized 13 C metabolic imaging to reconstruct separate metabolite images 31 ; based on their chemical shift.…”

Chemical shift separation with controlled aliasing for hyperpolarized 13C metabolic imaging

“…More specifically, we implemented a fast threedimensional (3D) pulse sequence together with an accompanying reconstruction method that can acquire signals from multiple 13 C metabolites simultaneously and later separate them into individual images. Our approach is based on the concept of separating aliased information using a parallel imaging formulation, which has been widely applied to multislice imaging (26), 3D imaging (27), and water-fat separation (28)(29)(30)(31). Here, we applied the idea to rapid 3D acquisitions of 13 C-pyruvate and 13 C-lactate in phantom studies as well as in normal rat experiments, achieving high-resolution images of both the compounds in the same time it would take to acquire a single metabolite with previous methods.…”