Preoperative assessment of cervical lymph node metastases in patients with papillary thyroid carcinoma: Incremental diagnostic value of dual-energy CT combined with ultrasound

Purpose To determine whether dual-energy CT (DECT) has incremental diagnostic value when combined with ultrasound (US) in the diagnosis of metastatic cervical lymph nodes (LNs) in patients with papillary thyroid carcinoma (PTC). Methods This was a single-center retrospective cohort study of patients diagnosed with PTC between October 2019 and August 2020. US features of LNs to include hyperechogenicity, round shape, microcalcification, cystic component, and homogeneous/peripheral vascularity were considered suggestive of metastasis. The HU of arterial phase (HU arterial ) and DECT-derived CT images [contrast media (CM) and areas under the 100 keV monoenergetic curve (AUC 100keV )] were measured. Effective atomic numbers (Z eff ), iodine concentration (mg/mL), and slope of the HU curve (λ HU ) were also obtained. The values for metastatic and benign LNs were compared using Student’s t -test with false-discovery correction. Logistic regression with areas under the receiver operating characteristic curves (AUCs) were performed for predicting metastatic LNs. Results A total of 102 patients were included (49 metastatic and 53 benign LNs; mean age, 46±15 years). Metastatic LNs showed significantly higher values for HU arterial , CM, Z eff , λ HU , AUC 100keV , and iodine concentration (all, P = 0.001). In logistic regression, the HU arterial demonstrated the highest AUC (0.824; 95% confidence interval [CI], 0.751–0.897), followed by CM HU (0.762; 95% CI, 0.679–0.846). Combination of DECT parameters with US features improved the AUC from 0.890 to 0.941. Conclusion Compared to US features alone, combination with DECT-derived quantitative parameters improved diagnostic performance in predicting metastatic cervical LNs in patients with PTC.