In a patient with back pain and a history of cancer, sensory loss below the nipple and leg weakness localize the lesion to which imaging as the best modality to confirm?

• A. CT chest
• B. MRI of the spine
• C. X-ray thoracic spine
• D. Ultrasound abdomen

Answer: (B)

When cancer has spread to the spine, back pain with neurologic symptoms like sensory loss in a dermatomal level (nipple corresponds to about T4) and leg weakness suggests metastatic disease with potential epidural cord compression. To confirm and precisely localize the lesion, MRI of the spine is the most informative test because it provides superior contrast for soft tissues, the spinal cord, nerve roots, and bone marrow. It can reveal metastatic deposits within the vertebral bodies, any epidural mass compressing the cord, and edema or intrinsic cord signal changes that explain the neurologic deficits.

CT and X-ray mainly show bony destruction and are less sensitive for marrow involvement or soft-tissue compression, while ultrasound of the abdomen isn’t relevant to the spine. Therefore, MRI is the best modality to confirm the diagnosis and guide urgent management.