Osteomyelitis in a nine-year-old girl with knee pain and fever

(A) Plain radiographs of the knee are unremarkable.
(B) T1 weighted MRI demonstrates marked decrease in signal intensity in the medial metaphysis and epiphysis of the distal femur. There is some involvement of the soft tissue.
(C) These findings are more pronounced in a T1 weighted MRI with gadolinium.