High-Resolution MR Imaging of Muscular Fat Fraction-Comparison of Three T 2 -Based Methods and Chemical Shift-Encoded Imaging.

Chemical shift-encoded imaging (CSEI) is the most common magnetic resonance imaging fat-water separation method. However, when high spatial resolution fat fraction (FF) images are desired, CSEI might be challenging owing to the increased interecho spacing. Here, 3 T-2-based methods have been assessed as alternative methods for obtaining high-resolution FF images. Images from the calf of 10 healthy volunteers were acquired; FF maps were then estimated using 3 T-2-based methods (2-and 3-parameter nonlinear least squares fit and a Bayesian probability method) and CSEI for reference. In addition, simulations were conducted to characterize the performance of various methods. Here, all T-2-based methods resulted in qualitatively improved high-resolution FF images compared with high-resolution CSEI. The 2-parameter fit showed best quantitative agreement to low-resolution CSEI, even at low FF. The estimated T-2-values of fat and water, and the estimated muscle FF of the calf, agreed well with previously published data. In conclusion, T-2-based methods can provide improved high-resolution FF images of the calf compared with the CSEI method.