[Role of MRI and CT in the evaluation of postirradiation status and complications in head and neck cancer].

Most head and neck cancer patients are treated with combined modalities such as surgery, radiotherapy (RT), chemotherapy (ChT). Concurrent chemo-radiation has improved treatment outcomes with increased toxic effects. Reactions after RT are divided into early and late changes. Early reactions are seen during the course of therapy or within 3 months; these are reversible in most cases. Late complications are observed 3 months to years after RT and they are generally irreversible. As typical late reaction radiation induced necrosis may occur in soft tissues, cartilage, bones and brain. Tumor recurrence and post-radiation necrosis typically appear at the same time, within 2-3 years after RT; the differentiation may be difficult. Computed tomography (CT) and magnetic resonance imaging (MRI) have become the gold standards not only for staging and assessing tumor response, but also to evaluate posttreatment status, to distinguish residual or recurrent tumor and RT complications. Using baseline CT or MRI between 2-3 months after treatment and performing standard follow-up imaging with strict clinical follow-up are required to establish early salvage treatment.