Preoperative Prediction of Cervical Lymph Node Metastasis in Papillary Thyroid Carcinoma Using Arterial Enhancement...

To evaluate the diagnostic value of arterial enhancement fraction (AEF) derived from dual-layer detector spectral CT (DLCT) in preoperative assessment of cervical lymph node metastasis in patients with papillary thyroid carcinoma (PTC), and to compare its performance with other spectral CT quantitative parameters and conventional CT features.

This retrospective study included 42 PTC patients, with a total of 94 lymph node lesions. The conventional CT morphological features of PTC primary lesions and lymph nodes were assessed. Quantitative spectral CT parameters evaluated in primary PTC lesions comprised arterial phase iodine density (AP-ID), venous phase iodine density (VP-ID), and the AEF was calculated accordingly. For lymph nodes, parameters evaluated in both arterial and venous phases comprised conventional images (CIs), virtual monoenergetic images (VMI), iodine density (ID), effective atomic number (Zeff), electron density (ED), spectral curve slope (λHU), and AEF. Receiver operating characteristic (ROC) curve analysis was employed to evaluate diagnostic performance.

The diameter, cystic change, and contrast enhancement pattern were significantly different between metastatic and nonmetastatic lymph nodes (p < 0.05). No statistically significant differences were observed between metastatic and nonmetastatic lymph nodes in terms of anatomical level, density, boundary, outline, and calcification (p > 0.05). Metastatic lymph nodes demonstrated significantly higher values in AP-CI, AP-VMI 40 keV, AP-VMI 100 keV, AP-ID, AP-Zeff, AP-λHU, and AEF compared to nonmetastatic nodes (p < 0.05). Among the evaluated spectral CT parameters, AEF showed the highest individual diagnostic performance, with an AUC of 0.775 (95% CI: 0.675-0.875). The combined model achieved an AUC of 0.809 (95% CI: 0.716-0.901), and the difference in AUC between AEF and the combined model was not statistically significant (p = 0.155).

AEF demonstrated significant differences between metastatic and nonmetastatic cervical lymph nodes and showed the highest individual diagnostic performance among the evaluated spectral CT parameters. AEF may serve as a quantitative imaging biomarker to assist the preoperative assessment of cervical lymph node metastasis in patients with PTC.

Quantitative parameters derived from DLCT, particularly the AEF, provided additional quantitative information for the preoperative assessment of cervical lymph node metastasis in patients with PTC. AEF showed promising diagnostic performance and may complement conventional CT evaluation for lymph node characterization.