Multi-Modality Quantitative Fat Phantom for MRI and CT Measurements of Steatotic Liver Disease

Motivation: A quantitative multi-modality fat phantom would facilitate quality assurance of liver fat quantification with MRI and CT. Goal(s): Develop a quantitative MRI-CT fat phantom that mimics MRI and CT properties of liver, including CT energy dependence. Approach: Vials were fabricated and placed into a newly designed pill-shaped housing and assessed on MRI and CT systems. Results: MRI and CT measurements were correlated by CT#[HU] = -2.57*PDFF+0.04*kV+0.0048*PDFF*kV+66.19, where PDFF is measured in % and kV is CT tube potential. The maximum CT number difference between 80 kV and 140 kV CT acquisitions was 14 HU. Impact: A quantitative multi-modality fat phantom was developed for quality assurance of MRI and CT fat quantification. The phantom mimics MRI proton-density fat fraction (PDFF) from 0-40% PDFF and the liver fat-to-CT# relationship, including the CT response across multiple kV levels.