Quantification of the Proton Density Fat Fraction and Iron Content: A Comparative Study Between 3.0 T and 5.0 T MRI

ABSTRACT Background Proton density fat fraction (PDFF) and R2* are noninvasive MRI biomarkers for quantifying fat and iron in abdominal organs. While 3.0 T MRI is widely used clinically, 5.0 T may offer improved accuracy and reliability. With the increasing availability of 5.0 T, assessing its feasibility and utility for quantifying PDFF and R2* in abdominal organs is needed. Purpose To determine the agreement of the PDFF and R2* in the liver, pancreas, kidney, and paraspinal muscle at 2 different field strengths. Study Type Prospective. Population A total of 127 participants, including 60 healthy volunteers and 67 with metabolic dysfunction‐associated steatotic liver disease (100 women and 27 men, 52 ± 9 years old). Field Strength/Sequence 3.0 T and 5.0 T; Chemical shift‐encoded multi‐echo gradient echo sequence. Assessment PDFF and R2* values in the liver, pancreas, kidney, and paraspinal muscle were measured by three observers to evaluate the interobserver and interfield agreement using two 3.0 T scanners (scanner 1 and scanner 2) and one 5.0 T scanner. Statistical Tests Linear regression, Bland–Altman analyses, and intraclass correlation coefficients (ICCs). The p ‐value < 0.05 indicated statistically significant. Results PDFF and R2* at 5.0 T were strongly correlated with those at two 3.0 T scanners for all organs ( R 2 = 0.905–0.998 for PDFF; 0.831–0.991 for R2*), indicating high interfield ICCs (0.892–0.993 for PDFF; 0.910–0.981 for R2*). Comparisons between 5.0 T and two 3.0 T scanners showed good interfield agreement for PDFF (mean bias, −0.57% to 0.03%) while a higher bias for R2* (mean bias, −16.53 to −2.64 s −1 , 95% LoA, −34.28 to 1.21 s −1 ) at 5.0 T compared to the comparison between 3T scanners. Data Conclusion 5.0 T revealed high interfield agreement between the PDFF and R2* with 3.0 T, which could provide reliable quantification of fat and iron contents in abdominal organs. Evidence Level 2. Technical Efficacy Stage 2.