Integrated 18F‐FDG PET/CT for the initial evaluation of cervical node level of patients with papillary thyroid carcinoma: comparison with ultrasound and contrast‐enhanced CT

Abstract

To compare the diagnostic accuracy of integrated 18F-fluorodeoxyglucose PET/CT with ultrasonography (US) and contrast enhanced CT (CECT) alone in the initial evaluation of cervical lymph node levels of patients with papillary thyroid carcinoma. From July 2004 to March 2005, 26 consecutive patients with papillary thyroid carcinoma, confirmed by aspiration cytology analysis, underwent US, CECT and PET/CT. The sensitivity, specificity and diagnostic accuracy of the US, CECT and PET/CT studies for the final status of 312 cervical node levels (levels I-V: 260, level VI: 52) were compared by employing a generalized estimating equation test. The final status of cervical node levels was determined by the surgical pathology and follow-up data. At all lymph node levels (levels I-VI), PET/CT showed a sensitivity of 30.4%, a specificity of 96.2% and a diagnostic accuracy of 86.9%. The corresponding values for US and CECT were 41.3%, 97.4%, 89.1% (US) and 34.8%, 96.2%, 87.2% (CECT). Considering only the lateral cervical node group (levels I-V), PET/CT showed a sensitivity of 50.0%, a specificity of 97.0% and a diagnostic accuracy of 92.3%. The corresponding values for US and CECT were 53.9%, 97.9%, 93.5% (US) and 42.3%, 96.6%, 91.2% (CECT). The diagnostic results for US, CECT and PET/CT upon initial evaluation of the cervical lymph nodes did not differ significantly on a level-by-level basis. Our preliminary results suggest that integrated PET/CT does not provide any additional benefit when compared to US and CECT for the initial evaluation of cervical node levels in patients with papillary thyroid carcinoma.