After initial X-rays, which imaging modality best delineates the extent of an osteosarcoma?

After initial X-rays, which imaging modality best delineates the extent of an osteosarcoma?

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

Answer: (A)

The key idea is that local tumor extent in bone cancers is best mapped with high soft-tissue contrast imaging. MRI provides superior delineation of both bone marrow involvement and the surrounding soft tissues, making it the most reliable way to define how far osteosarcoma extends. This precise information is crucial for planning surgical margins and determining feasibility of limb-sparing procedures. CT can show cortical bone detail and calcifications but isn’t as good as MRI for the soft-tissue and marrow boundaries. Ultrasound isn’t useful for intraosseous lesions, and PET helps with systemic/metabolic staging rather than exact local extent. So MRI is the best choice to delineate the tumor’s extent.

The key idea is that local tumor extent in bone cancers is best mapped with high soft-tissue contrast imaging. MRI provides superior delineation of both bone marrow involvement and the surrounding soft tissues, making it the most reliable way to define how far osteosarcoma extends. This precise information is crucial for planning surgical margins and determining feasibility of limb-sparing procedures. CT can show cortical bone detail and calcifications but isn’t as good as MRI for the soft-tissue and marrow boundaries. Ultrasound isn’t useful for intraosseous lesions, and PET helps with systemic/metabolic staging rather than exact local extent. So MRI is the best choice to delineate the tumor’s extent.