MRI appearance of radiation-induced changes of normal cervical tissues

Irradiation causes specific MRI changes in anatomic morphology and signal i ntensity. To avoid misinterpretation, it is important to consider the poten tial radiation changes of normal tissue in MRI. The aim of this study was t o describe the detected radiation effects on normal cervical tissues in MRI . Pretreatment and posttreatment MRI of 52 patients with primary neck tumor s were evaluated retrospectively. The MR imaging was performed before initi ating radiotherapy and at the end of the treatment period. Patients underwe nt follow-up studies within 24 months after the end of irradiation. Edema w as the main radiation-induced effect. It was detected in the epiglottis, la rynx, pharynx wall, retro- and parapharyngeal space, salivary glands, muscl es, and subcutaneous tissue. In some cases the bone marrow of the mandible showed edema, due to osteonecrosis. We additionally detected fluid accumula tion in the mastoid cells. Radiation caused volume reduction of the parotid gland, thickening of the pharynx wall, and fatty degeneration of bone marr ow. Magnetic resonance imaging is an excellent method of depicting radiatio n-induced changes of normal tissue. Especially T2-weighted sequences allow the detection of even slight edema. It is important to be aware of the most common radiation-induced changes in MRI and to take them into account when assessing an examination.