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

Abstract

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_S) and DECT-derived AEF (AEF_D) were calculated. Correlation between AEF_D and AEF_S 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_S, and conventional features + AEF_D). 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_D (1.14 vs 0.48; p < 0.001) and AEF_S (1.08 vs 0.38; p < 0.001) than non-metastatic LNs. AEF_D correlated well with AEF_S (r = 0.802; p < 0.001), and exhibited comparable performance with AEF_S (AUC, 0.867 vs 0.852; p = 0.628). Combining CT image features with AEF_S (model 2) and AEF_D (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_D correlated well with AEF_S, and exhibited comparable performance with AEF_S. Integrating qualitative CT image features with both AEF_S and AEF_D 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_S) than non-metastatic LNs in patients with papillary thyroid cancer. • DECT-derived AEF (AEF_D) correlated significantly with AEF_S, and exhibited comparable performance with AEF_S. • Integrating qualitative CT images features with both AEF_S and AEF_D could further improve the differential ability.

Keywords: Logistic models; Lymph nodes; Lymphatic metastasis; Thyroid cancer, papillary; Tomography, x-ray computed.