Which imaging modality is most helpful to detect occult vertebral fractures when initial X-ray results are inconclusive?

• A. CT
• B. DEXA
• C. Ultrasound
• D. MRI

Answer: (D)

Occult vertebral fractures can hide on plain X-rays because early fractures may not disrupt the bone cortex in a way that's visible on radiographs. The telling sign is a bone that has fractured but appears radiographically quiet. Imaging that reveals bone marrow changes and soft-tissue reactions is most informative in this situation, and that’s where MRI excels. MRI can detect bone marrow edema, a hallmark of an acute fracture, even when there’s no clear fracture line on X-ray. This edema appears on specific sequences (like STIR) and confirms that a vertebral body is acutely injured, helping distinguish new injuries from old changes. MRI also provides angles on spinal alignment, disc health, and surrounding structures, which aids in planning treatment and monitoring stability. CT can pick up cortical disruption when a fracture is evident on the outer bone, but it’s less sensitive than MRI for early or occult fractures because it doesn’t show marrow edema as clearly. DEXA measures bone density, not fracture visualization, and ultrasound isn’t useful for evaluating the vertebral bodies. So the modality that best detects occult vertebral fractures after inconclusive initial X-rays is MRI.