Fig. 4.

A 79-year-old woman presented with fever and symptoms of right foot infection. (a) Sagittal contrast-enhanced T1-W FS MR image of the right foot shows the ‘tram-track’ pattern of enhancement of a sinus tract in the subcutaneous layer of the plantar forefoot (arrowhead). (b& c) Coronal contrast-enhanced T1-W FS MR images of the right foot taken at two separate locations. (b) The sinus tract extends to a subcutaneous abscess (asterisk), adjacent to the base of the first metatarsal and with an overlying skin ulcer. The adjacent bone marrow enhances, suggesting osteomyelitis (white arrow). (c) Further distally in the right forefoot, the cross-sectional appearance of the sinus tract is demonstrated as a round rim-enhancing fluid collection, which may be mistaken for an abscess if not evaluated properly (black arrow).