Bone Marrow Proton Density Fat Fraction Measurement Using Flip-Angle Modulated Chemical Shift-Encoded MRI

Motivation: Non-invasive measurement of bone marrow fat content, which helps characterize and monitor hematologic disease processes, is a major unmet need. Chemical-shift-encoded (CSE) MRI with 2D flip-angle modulation (FAM) offers a motion-robust alternative to 3D-CSE MRI for PDFF measurement. Goal(s): To compare bone marrow PDFF measured using FAM-CSE and 3D-CSE MRI. Approach: Single-center retrospective study of patients who underwent both FAM-CSE and 3D-CSE MRI; vertebral body PDFF measured using both techniques were compared for linearity and bias. Results: Bone marrow PDFF measured using FAM-CSE and 3D-CSE MRI demonstrate strong linearity, but also non-negligible relative bias compared to each other. Impact: FAM-based CSE MRI is a promising tool for motion-robust measurement of bone marrow PDFF, which may help characterization of many hematologic disease processes. However, it requires further validation and addressing potential sources of bias.