Extracellular Volume Fraction Derived From Dual-Layer Spectral Detector Computed Tomography for Diagnosing Cervical Lymph Nodes Metastasis in Patients With Papillary Thyroid Cancer: A Preliminary Study
Yan Zhou, Di Geng, Guo-Yi Su, Xingbiao Chen, Yan Si, Meiping Shen, Xiao‐Quan Xu, Fei‐Yun Wu
Abstract
Objectives The current study evaluates the performance of dual-energy computed tomography (DECT) derived extracellular volume (ECV) fraction based on dual-layer spectral detector CT for diagnosing cervical lymph nodes (LNs) metastasis from papillary thyroid cancer (PTC) and compares it with the value of ECV derived from conventional single-energy CT (SECT). Methods One hundred and fifty-seven cervical LNs (81 non-metastatic and 76 metastatic) were recruited. Among them, 59 cervical LNs (27 non-metastatic and 32 metastatic) were affected by cervical root artifact on the contrast-enhanced CT images in the arterial phase. Both the SECT-derived ECV fraction (ECV S ) and the DECT-derived ECV fraction (ECV D ) were calculated. A Pearson correlation coefficient and a Bland–Altman analysis were performed to evaluate the correlations between ECV D and ECV S . Receiver operator characteristic curves analysis and the Delong method were performed to assess and compare the diagnostic performance. Results ECV D correlated significantly with ECV S (r = 0.925; p <0.001) with a small bias (−0.6). Metastatic LNs showed significantly higher ECV D (42.41% vs 22.53%, p <0.001) and ECV S (39.18% vs 25.45%, p <0.001) than non-metastatic LNs. By setting an ECV D of 36.45% as the cut-off value, optimal diagnostic performance could be achieved (AUC = 0.813), which was comparable with that of ECV S (cut-off value = 34.99%; AUC = 0.793) (p = 0.265). For LNs affected by cervical root artifact, ECV D also showed favorable efficiency (AUC = 0.756), which was also comparable with that of ECV S (AUC = 0.716) (p = 0.244). Conclusions ECV D showed a significant correlation with ECV S . Compared with ECV S , ECV D showed comparable performance in diagnosing metastatic cervical LNs in PTC patients, even though the LNs were affected by cervical root artifacts on arterial phase CT.