Fig. 3.

Axial T2-weighted 7-T MR image (left panel) of the left knee, demonstrating a displaced osteochondral fragment re-attachment (arrowhead) at the medial facet of the patella. Synovial fluid is seen within a full-thickness fissure (arrow). On the conventional ²³Na map (middle panel), hyperintense signal is seen from synovial fluid within the fissure (arrow). On the ²³Na-IR map (right panel), there is suppression of signal from synovial fluid within the fissure. The calibration phantoms containing 300 mM, 250 mM, 200 mM and 150 mM are seen at the anterior aspect of the knee. The sodium images represent concentration maps with coloured bars indicating range of [Na⁺] in mM (red=600 mM, blue=0 mM)