Scan–Rescan Repeatability and Impact of B0 and B1 Field Nonuniformity Corrections in Single‐Point Whole‐Brain Macromolecular Proton Fraction Mapping

Background Single‐point macromolecular proton fraction (MPF) mapping is a recent quantitative MRI method for fast assessment of brain myelination. Information about reproducibility and sensitivity of MPF mapping to magnetic field nonuniformity is important for clinical applications. Purpose To assess scan–rescan repeatability and a value of B0 and B1 field inhomogeneity corrections in single‐point synthetic‐reference MPF mapping. Study Type Prospective. Population Eight healthy adult volunteers underwent two scans with 11.5 ± 2.3 months interval. Field Strength/Sequence 3T; whole‐brain 3D MPF mapping protocol included three spoiled gradient‐echo sequences providing T1, proton density, and magnetization transfer contrasts with 1.25 × 1.25 × 1.25 mm3 resolution and B0 and B1 mapping sequences. Assessment MPF maps were reconstructed with B0 and B1 field nonuniformity correction, B0‐ and B1‐only corrections, and without corrections. Mean MPF values were measured in automatically segmented white matter (WM) and gray matter (GM). Statistical Tests Within‐subject coefficient of variation (CV), intraclass correlation coefficient (ICC), Bland–Altman plots, and paired t‐tests to assess scan–rescan repeatability. Repeated‐measures analysis of variance (ANOVA) to compare field corrections. Results Maximal relative local MPF errors without correction in the areas of largest field nonuniformities were about 5% and 27% for B0 and B1, respectively. The effect of B0 correction was insignificant for whole‐brain WM (P > 0.25) and GM (P > 0.98) MPF. The absence of B1 correction caused a positive relative bias of 4–5% (P