Accuracy of preoperative MRI to assess lateral neck metastases in papillary thyroid carcinoma

Primary treatment of papillary thyroid carcinoma (PTC) with lateral lymph node metastasis is surgery, but the extent of lateral neck dissection remains undefined. Preoperative imaging is used to guide the extent of surgery, although its sensitivity and specificity for defining the number and level of affected lymph nodes on the lateral neck is relatively modest. Our aim was to assess the role of preoperative magnetic resonance imaging (MRI) in predicting the requisite levels of neck dissection in patients with regionally metastatic PTC, with a focus on Levels II and V. All patients with PTC and lateral neck metastasis who had undergone neck dissection at the Department of Otorhinolaryngology-Head and Neck Surgery, Helsinki University Hospital, Helsinki, Finland from 2013 to 2016 and had a preoperative MRI available were retrospectively reviewed. A head and neck radiologist re-evaluated all MRIs, and the imaging findings were compared with histopathology after neck dissection. In the cohort of 39 patients, preoperative MRI showed concordance with histopathology for Levels II and V as follows: sensitivity of 94 and 67%, specificity of 20 and 91%, positive predictive value of 56 and 75%, and negative predictive value of 75 and 87%, respectively. In PTC, MRI demonstrated fairly high specificity and negative predictive value for Level V metastasis, and future studies are needed to verify our results to omit prophylactic dissection of this level. Routine dissection of Level II in patients with regionally metastatic PTC needs to be considered, as MRI showed low specificity.