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

Objective: 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. Patients and measurements: 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. Results: 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. Conclusion: 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.