Bone marrow edema syndrome of the foot: one year follow-up with MR imaging

Objective: To describe the MR findings of bone marrow edema syndrome (BMES) of the foot and its evolution at 1 year follow-up. Design and patients: Twenty-five of 32 patients with disabling foot and ankle pain unrelated to trauma diagnosed as BMES when MR imaging demonstrated a bone marrow edema pattern in one or more bones without any radiological or underlying clinical cause, were re-evaluated by MR imaging 1 year later. Results: On the initial MR examinations an average of 4.7 individual bones were involved by bone marrow edema. Soft tissue edema was present in every patient and joint effusion in 10 patients. MR imaging at 1 year showed resolution of bone edema in 18 patients (72%), partial improvement in five (20%) and no improvement in two (8%). Six patients (24%) developed similar symptoms in the other foot during follow-up. Ten of 17 available plain radiographs showed some loss of radiodensity. Further bone marrow edema developed in bones of the same foot that were initially normal, or in uninvolved distant bone marrow areas in the same affected bone, in six of seven patients on follow-up MR imaging. Conclusions: The evolution of the MR findings of BMES of the foot is to complete resolution or partial improvement at 1 year in the majority of cases. Migration to the other foot occurs in up to a quarter of patients.