Linearity and Bias of Bone Marrow Relative Fat-fraction Compared to Proton Density Fat-Fraction

Bone marrow relative fat-fraction (rFF) measured using dual-echo gradient echo (GRE) in- and opposed phase imaging, has been proposed as an early predictor of treatment response in multiple myeloma. In this work we demonstrate that in patients without known bone marrow pathology (referred for liver fat/iron quantification), bone marrow rFF is unreliable and suffers from large bias when compared with proton density fat-fraction (PDFF), acquired using quantitative chemical-shift encoded (CSE) MRI. Hence, PDFF should be considered for future approaches using bone marrow fat-fraction as a predictor of treatment response in multiple myeloma.