Fig. 2.

a Resting sodium MR image (TR=80 ms, TE=0.160 ms, 4 mm × 4 mm × 4 mm) from the calf of a healthy volunteer. The NaCl phantoms can be seen at the anterior aspect of the leg. b Immediate post-exercise sodium MR image from the same volunteer, showing subtle increase in sodium signal intensity within the posterior compartment muscles. c Corresponding proton 3D fast low angle shot (FLASH) MR image (TR=20 ms, TE=5 ms, 0.195 mm × 0.195 mm, 1-mm slice thickness) from the same volunteer, which was performed after the sodium MRI to delineate muscle anatomy. TA tibialis anterior, S soleus, G gastrocnemius. Coil inhomogeneity artefact is seen at the anterior and posterior aspects of the leg