Figure 5.

Performance of each ∆B ₀ correction method under unaltered conditions for volunteer V2: The first row shows the color‐coded ∆B ₀ maps of the static correction methods (CEST‐minZ, WASSR, and GRE‐2TE) and the first ∆B ₀ map from the dynamic methods (NAV‐EPI‐2TE, CEST‐GRE‐1TE, and CEST‐GRE‐2TE). Below, color‐coded maps of ∆B ₀‐corrected MTR_asym values for the frequency ranges |0.3–1.0|, |1–2|, and |3–4| ppm are displayed in the second, third, and fourth rows, respectively. The outline of the brain, defining voxels included in the mean MTR_asym (see Section “Data analysis”), is indicated in black. The dynamic method CEST‐GRE‐1TE appears to estimate slightly lower B ₀ compared to method CEST‐GRE‐2TE, producing a higher‐valued MTR_asym map. The NAV‐EPI‐2TE shows the opposite effect (overestimation of B ₀ compared to CEST‐GRE‐2TE) in the frontal region. CEST‐minZ, determination of the water resonance frequency from the Z‐spectrum; GRE‐2TE, MTR_asym, gradient echo‐2TE‐asymmetric magnetization transfer ratio; NAV‐EPI‐2TE,navigator‐echoplanar imaging‐2TE; WASSR, water saturation shift referencing