skip to main content

AVN MRI Double-Line Sign — SCE Rheumatology MCQ

Instant feedback + full explanation. One question, done properly.

ModerateMusculoskeletal ImagingAVN MRI Double-Line SignSCE Rheumatology

A 65-year-old woman with rheumatoid arthritis has received long-term oral prednisolone. She develops severe atraumatic groin pain. MRI of the hip shows a subchondral lesion in the anterosuperior femoral head bounded by a serpiginous low-signal-intensity line on T1-weighted images. On T2-weighted images, the boundary has an outer low-signal rim and an inner high-signal rim, with surrounding bone marrow oedema. What is the most likely diagnosis?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — Osteonecrosis of the femoral head

The diagnosis is osteonecrosis of the femoral head. Long-term systemic glucocorticoid exposure is a major risk factor, and the decisive finding is the MRI double-line sign: an outer low-signal rim with an inner high-signal rim at the interface between necrotic and viable bone. A serpiginous T1-hypointense boundary is also characteristic. Bone marrow oedema can accompany symptomatic disease but is not itself specific. Transient bone marrow oedema syndrome produces diffuse oedema without the characteristic demarcating double line. A subchondral insufficiency fracture may cause acute pain and oedema in an older patient, but typically shows a fracture-related low-signal band rather than the paired rims described. Septic arthritis would principally produce synovitis and an effusion, while osteoarthritis would show cartilage loss and degenerative subchondral change.

Reference: König M et al. Avascular necrosis of the femoral head, MRI findings and differential diagnosis, 2025. https://pubmed.ncbi.nlm.nih.gov/41326722/