Added Value of Arterial Enhancement Fraction Derived from Dual-energy Computed Tomography for Preoperative Diagnosis of Cervical Lymph Node Metastasis in Papillary Thyroid Cancer: Initial Results

Objectives: To explore the added value of arterial enhancement fraction (AEF) derived from dual-energy computed tomography CT (DECT) to conventional image features for diagnosing cervical lymph node (LN) metastasis in papillary thyroid cancer (PTC).

Methods: A total of 273 cervical LNs (153 non-metastatic and 120 metastatic) were recruited from 92 patients with PTC. Qualitative image features of LNs were assessed. Both single-energy CT (SECT)-derived AEF (AEF) and DECT-derived AEF (AEF) were calculated. Correlation between AEF and AEF was determined using Pearson's correlation coefficient. Multivariate logistic regression analysis with the forward variable selection method was used to build three models (conventional features, conventional features + AEF, and conventional features + AEF). Diagnostic performances were evaluated using receiver operating characteristic (ROC) curve analyses.

Results: Abnormal enhancement, calcification, and cystic change were chosen to build model 1 and the model provided moderate diagnostic performance with an area under the ROC curve (AUC) of 0.675. Metastatic LNs demonstrated both significantly higher AEF (1.14 vs 0.48; p < 0.001) and AEF (1.08 vs 0.38; p < 0.001) than non-metastatic LNs. AEF correlated well with AEF (r = 0.802; p < 0.001), and exhibited comparable performance with AEF (AUC, 0.867 vs 0.852; p = 0.628). Combining CT image features with AEF (model 2) and AEF (model 3) could significantly improve diagnostic performances (AUC, 0.865 vs 0.675; AUC, 0.883 vs 0.675; both p < 0.001).

Conclusions: AEF correlated well with AEF, and exhibited comparable performance with AEF. Integrating qualitative CT image features with both AEF and AEF could further improve the ability in diagnosing cervical LN metastasis in PTC.

Clinical Relevance Statement: Arterial enhancement fraction (AEF) values, especially AEF derived from dual-energy computed tomography, can help to diagnose cervical lymph node metastasis in patients with papillary thyroid cancer, and complement conventional CT image features for improved clinical decision making.

Key Points: • Metastatic cervical lymph nodes (LNs) demonstrated significantly higher arterial enhancement fraction (AEF) derived from dual-energy computed tomography (DECT) and single-energy CT (SECT)-derived AEF (AEF) than non-metastatic LNs in patients with papillary thyroid cancer. • DECT-derived AEF (AEF) correlated significantly with AEF, and exhibited comparable performance with AEF. • Integrating qualitative CT images features with both AEF and AEF could further improve the differential ability.