Proton density fat fraction: magnetic resonance imaging applications beyond the liver.

Magnetic resonance imaging-proton density fat fraction (MRI-PDFF) is an emerging quantitative imaging biomarker that accurately measures the fat fraction of tissue by correcting factors influencing magnetic resonance signal intensity. Beyond fat quantification, it also measures R2* which is a direct measure of iron concentration. The utilization of MRI-PDFF in liver diseases is well established. In the present review, we focused on applications of MRI-PDFF in different body areas including pancreas, bone, muscle, spleen, testis, visceral, and subcutaneous adipose tissue. Future studies can enable tracking of quantitative fat fraction changes in different organs simultaneously, which can be critical in understanding fat metabolism.