Fig. 9.

A 49-year-old man presented with low-grade fever and signs of right foot infection. Sagittal (a) T1-W, (b) T2-W FS and (c) contrast-enhanced T1-W FS MR images of the right foot show extensive bony destruction centred around the midfoot joints, consistent with chronic neuroarthropathy. This is well demonstrated on the accompanying (d) oblique radiograph of the right foot. On the MR images, abnormal marrow signal is seen diffusely in the bones of the midfoot, extending beyond the subchondral bone; the affected bones show marked low T1-W signal and corresponding high T2-W signal as well as enhancement (arrows). The ‘ghost sign’ is present, with better delineation of the involved bones on the T2-W FS and contrast-enhanced T1-W FS images, compared to the T1-W image (in which the bones ‘disappear’). MR imaging appearances suggest osteomyelitis. Secondary signs of infection are present, with a rim-enhancing abscess tracking into the intertarsal joints and extending to the subcutaneous layer via a sinus tract (thin arrows). Surrounding soft tissue enhancement and the absence of subcutaneous fat signal intensity are noted (asterisks). There is suggestion of a sequestrum (arrowhead).