Effect of Hashimoto’s thyroiditis on the dual-energy CT quantitative parameters and performance in diagnosing metastatic cervical lymph nodes in patients with papillary thyroid cancer

Background To evaluate the effect of Hashimoto’s thyroiditis (HT) on dual-energy computed tomography (DECT) quantitative parameters of cervical lymph nodes (LNs) in patients with papillary thyroid cancer (PTC), and its effect on the diagnostic performance and threshold of DECT in preoperatively identifying metastatic cervical LNs. Methods A total of 479 LNs from 233 PTC patients were classified into four groups: HT+/LN+, HT+/LN−, HT−/LN + and HT−/LN − group. DECT quantitative parameters including iodine concentration (IC), normalized IC (NIC), effective atomic number (Z eff ), and slope of the spectral Hounsfield unit curve (λ HU ) in the arterial phase (AP) and venous phase were compared. Receiver operating characteristic curve analyses were performed to evaluate DECT parameters’ diagnostic performance in differentiating metastatic from nonmetastatic LNs in the HT − and HT + groups. Results The HT+/LN + group exhibited lower values of DECT parameters than the HT−/LN + group (all p < 0.05). Conversely, the HT+/LN − group exhibited higher values of DECT parameters than the HT−/LN − group (all p < 0.05). In the HT + group, if an AP-IC of 1.850 mg/mL was used as the threshold value, then the optimal diagnostic performance (area under the curve, 0.757; sensitivity, 69.4%; specificity, 71.0%) could be obtained. The optimal threshold value of AP-IC in the HT − group was 2.050 mg/mL. In contrast, in the HT − group, AP-NIC demonstrated the highest area under the curve of 0.988, when an optimal threshold of 0.243 was used. The optimal threshold value of AP-NIC was 0.188 in the HT + group. Conclusions HT affected DECT quantitative parameters of LNs and subsequent the diagnostic thresholds. When using DECT to diagnose metastatic LNs in patients with PTC, whether HT is coexistent should be clarified considering the different diagnostic thresholds.