Value of CT added to ultrasonography for the diagnosis of lymph node metastasis in patients with thyroid cancer

Background The benefit of CT for the diagnosis of lymph node metastasis in patients with thyroid cancer is still unclear. Methods Three hundred fifty‐one patients with thyroid cancers from 7 hospitals were prospectively enrolled in order to compare diagnostic performance between a combination of ultrasound and CT (ultrasound/CT) and ultrasound alone for prediction of lymph node metastasis and to calculate patient‐based benefits of CT added to ultrasound. Results Of 801 pathologically proven neck levels, ultrasound/CT showed higher sensitivities in both central and lateral compartments and improved accuracy in the lateral compartment compared to ultrasound alone. In the retropharyngeal/superior mediastinal compartment, although CT could detect lymph node metastasis an ultrasound could not. Patient‐based benefit was demonstrated in 13.1% of patients (46/351), and was higher in patients with cancers >1 cm than cancers ≤1 cm. Conclusion In patients with thyroid cancer, CT improved surgical planning by enhancing the sensitivity for lymph node metastasis and by detecting lymph node metastasis that was overlooked with ultrasound alone.