Anal carcinomas: the role of endoanal ultrasound and magnetic resonance imaging in staging, response evaluation and follow-up.

Anal carcinoma is an important but rare condition, managed in specialist centres. Both endoanal ultrasound and magnetic resonance imaging (MRI) can be used in the locoregional staging and follow-up of patients with anal cancer, and both may assist in treatment planning and prognosis. Recent guidelines published by the European Society for Medical Oncology have recommended MRI as the technique of choice for assessment of locoregional disease. This paper describes the techniques for both endoanal ultrasound and MRI, and compares the relative merits and disadvantages of each in the local assessment of anal carcinoma.