Staging papillary carcinoma of the thyroid: Magnetic resonance imaging vs ultrasound of the neck

AIM: To evaluate the role of magnetic resonance imaging (MRI) for staging l ocal disease and lymph node metastases in papillary carcinoma of the thyroi d by comparing MRI with ultrasound (US) of the neck. MATERIALS AND METHODS: Fourteen patients with papillary carcinoma underwent MRI and US. The images were prospectively reviewed for (1) identification of the primary lesion; (2) presence of multifocal thyroid disease; (3) extr acapsular extension; (4) invasion into the trachea, oesophagus and major ve ssels; and (5) presence of lymph node metastases, Correlation was made with the surgical findings. RESULTS: The site of the primary lesion was correctly identified by US in 1 4 of 14 (100%) and by MRI in 13 of 14 (93%) of patients. Multifocal thyroid tumour was correctly Identified by US in two of two patients (100%) and by MRI in zero of two (0%). Extracapsular extension(n = 9), oesophageal invas ion (n = 1) and tracheal invasion (n = 2) were identified by MRI in seven, zero, and one, and by US in six, zero and zero patients, respectively. Inva sion of the major vessels was not seen, Metastatic cervical nodes were pres ent in 19 nodal groups in 10 patients involving the internal jugular chain (n = 10), posterior triangle (n = 4) supraclavicular fossa (n = 1) and cent ral group (n = 4), Both MRI and US failed to identify metastatic nodes in t he central group but correctly identified 14 of the 15 nodal groups outside the central group. CONCLUSION: Ultrasound should be used as the first line of investigation fo r detecting the primary lesion, multifocal disease and cervical lymphadenop athy, In cases where the primary tumour is not surrounded by normal thyroid tissue MR imaging should be added to assess extracapsular spread, especial ly into the trachea. (C) 2000 The Royal College of Radiologists.