Fig 3. A, Coronal and (B) axial T1-weighted postcontrast MR image in a 40-year-old man with a 5-cm rapidly growing contrast-enhancing polyp with a more central area of reduced contrast enhancement radiating to the periphery, 2 years after treatment with conventional radiation therapy plus a stereotactic radiation therapy boost. Inflammatory changes and retained secretions are present in the sphenoid sinus.