Radiation-related changes can mimic recurrent or residual tumor, and can be difficult to differentiate from it. These changes are due to lymphatic and vascular obstruction, altered vascular permeability, and later on, fibrosis. Radiation-related changes have a characteristic pattern on both magnetic resonance imaging (MRI) and computed tomography (CT) that can help differentiate them from recurrent tumor. Radiation-related changes can affect the majority of the tissues of the head and neck. They can begin during therapy and many are present in virtually all patients from within 2 weeks following the end of therapy through 6 months following therapy. In many cases many of these changes begin to diminish after 6 months, but in some patients they can persist for much longer periods of time. The majority of patients will have laryngeal, pharyngeal, subcutaneous and epiglottic edema initially. Edema can persist, but in many patients these tissues will become fibrotic with time.

Findings Related to Radiation Changes