Wk 3, Case 4 - Review

EXAM: MRI Right Knee without and with IV Contrast

INDICATION: 10-year-old female with fever

TECHNIQUE: MR imaging was performed utilizing multiple pulse sequences both before and after the administration of IV contrast.

FINDINGS:

The medial and lateral menisci are intact. The anterior and posterior cruciate ligaments are intact.

The medial collateral ligament is intact. The iliotibial band, mid third lateral capsular ligament, fibular collateral ligament, biceps femoris tendon and conjoined tendon are intact.

The quadriceps tendon and patella ligament are intact. The articular cartilage surfaces are intact.

There is a large joint effusion with marked synovial enhancement, compatible with synovitis.

There is extensive abnormal marrow signal in the distal femoral metaphysis extending to the growth plate, compatible with marrow edema. On postcontrast sequences, the same area demonstrates enhancement.

The is a 12x9x12 mm rim-enhancing lesion located along the superior and medial aspect of the distal femoral physis. The cortical bone posterior to this lesion is thinned, indicating bone destruction. The location of the lesion correlates with the focal lucency seen in a corresponding location on the knee radiograph. The marrow signal of the epiphysis is otherwise normal, with only minimal edema, likely reactive.

There is edema in the surrounding musculature and soft tissues of the posterior knee, compatible with cellulitis and myositis.

IMPRESSIONS:

Distal femoral metaphyseal osteomyelitis. Small abscess along the posteromedial aspect of the physis. The infection does not appear to have spread to the epiphysis. Large enhancing joint effusion concerning for septic arthritis.