In suspected osteosarcoma, what is the recommended order of imaging studies?

• A. MRI first
• B. X-rays first, followed by MRI
• C. CT first
• D. Ultrasound then CT

Answer: (B)

Plain radiographs are the best first test when a bone tumor like osteosarcoma is suspected because they’re quick, widely available, and inexpensive, and they can reveal focal bone destruction with characteristic aggressive periosteal reactions (such as sunburst patterns or Codman triangles) that raise strong suspicion for a malignant process. This initial imaging helps confirm that a lesion is present and guides subsequent, more detailed studies.

After an abnormal X-ray, MRI is the study that provides the clearest picture of how far the disease has spread within the bone and into surrounding soft tissues. MRI excels at showing marrow involvement, the full extent of the intramedullary and extraosseous tumor, and the relationship to nearby nerves, vessels, and muscles, which is essential for biopsy planning and surgical approach.

CT has a role, particularly for detailed assessment of cortical bone or for chest evaluation in staging, but it’s not the preferred initial step. Ultrasound isn’t useful for characterizing primary bone tumors.