Figure 1.

(a) Summary of Bloch‐Siegert four‐angle saturation transfer protocol steps. (b) ¹H mid‐short‐axis localizer with the chemical shift imaging matrix overlaid and the target septal voxel shaded. (c‐e) Spectra from that target voxel. (c) Bloch‐Siegert $B_1^{+}$ mapping scans (steps 1‐2). (d) Unsaturated, control saturation, and saturated scans at FA = β. (e) Control and saturated scans at FA = α. Note that the PCr signal‐to‐noise ratio in scan 6 (FA = β, control saturation scan) was 17.5.

ATP, adenosine triphosphate; FA = flip angle; FAST, four‐angle saturation transfer; PCr, phosphocreatine.