Fig. 4.

(a) T2 weighted anatomical sequence, axial slice through the neck on the level of the thyroid (b) Diffusion weighted image with b-value = 0 s/mm², note the distortion of the thyroid isthmus due to its location between the extracorporal and tracheal air. Sample ROI definitions in the left thyroid, muscle and CSF are shown (dashed yellow lines). This image was used for the fusion with the parametric maps in (c–f) as determined in the by-voxel IVIM analysis: (c) Optimal b-value threshold (d) Perfusion fraction Fp [%] (e) Diffusion coefficient D [mm²/s] (f) Pseudodiffusion coefficient D* [mm²/s].