Added value of dual-energy CT to ultrasound assessment for AJCC 8th staging of papillary thyroid carcinoma

Background Accurate staging is crucial for guiding treatment decisions and surgical planning in papillary thyroid carcinoma (PTC). Purpose To determine whether dual-energy computed tomography (DECT) can improve the accuracy of ultrasound (US) assessment for the 8th edition of the American Joint Committee on Cancer (AJCC) staging of PTC. Material and Methods This retrospective study included 325 patients with PTC who underwent US and DECT before radical thyroidectomy. Using pathological results as the reference standard, the diagnostic accuracy of US, DECT, and US + DECT assessments for primary tumor (pT), regional lymph node (pN), and AJCC 8th staging were compared. McNemar’s test was used for head-to-head accuracy comparisons between DECT or US + DECT and US. Inter-observer agreement was assessed using intraclass correlation coefficients (ICCs). Results DECT showed significantly higher accuracy than US in pT evaluation (0.754 vs. 0.628; P < 0.001). DECT showed slightly higher accuracy than US in pN evaluation (0.662 vs. 0.652; P = 0.250). Combining DECT and US led to higher accuracy than US alone for both pT (0.655 vs. 0.628; P = 0.004) and pN (0.686 vs 0.652; P = 0.001) evaluation, specifically in T3b tumors (odds ratio [OR] 2.024; P = 0.043), T4 tumors (OR 8.125; P = 0.005), and N1b nodules (OR 2.027; P = 0.045). Combining DECT and US was associated with 95% higher odds of accuracy than US alone in AJCC 8th Stage II evaluation (OR 10.000; P = 0.041). Conclusion Combining DECT and US can improve US evaluation of pT and pN of PTC and the identification of Stage II PTC.