RESUMO
Objective To investigate the diagnostic value of dual energy CT for small central cervical metastatic lymph nodes in patients with papillary thyroid cancer.Methods The data of 43 patients with thyroid papillary carcinoma confirmed by pathology were retrospectively analyzed.All of the patients underwent dual energy CT scan before operation.The short diameter,iodine concentration and normalized iodine concentration (NIC) of enhanced arterial and venous phases and the slope of the energy spectrum curve were analyzed between metastatic central cervical lymph nodes and non-metastatic lymph nodes.ROC curve was used to analyze the diagnosis efficacy of iodine concentration and NIC for metastatic lymph nodes of thyroid carcinoma.Results Totally there were 119 lymph nodes in 43 patients included 55 thyroid papillary carcinoma metastasis lymph nodes (metastasis group) and 64 non-metastatic lymph nodes (non-metastasis group).There was significant differences of the mean short diameter of the lymph nodes between the two groupos (t=-2.20,P=0.03).In arterial phase,the average iodine concentration of metastasis group and non-metastasis group were (2.93±1.62)mg/ml and (2.17±1.09)mg/ml;the NIC were 0.33±0.21 and 0.19 ± 0.12;and the slope of the energy spectrum curve were 0.79±0.43 and 0.63±0.37 respectively.In venous phase,the average iodine concentration of metastasis group and non-metastasis group were (2.68± 1.54) mg/ml and (2.17 ± 1.01) mg/ml;the NIC were 0.51 ± 0.18 and 0.43 ± 0.15;the slope of the energy spectrum curve were 0.54 ± 0.42 and 0.62 ± 0.39 respectively.The iodine concentration and NIC in both phases and the slope of spectrum curve in arterial phase had statistical differences between the metastasis and non-metastasis groups (all P＜0.05).ROC curve showed that the area under the curve (AUC) of iodine concentration and NIC in the diagnosis of metastatic lymph nodes were 0.62 and 0.73 in arterial phase,respectively.And the AUC of iodine concentration and NIC were 0.61 and 0.63 in venous phase,respectively.Conclusion There are differences of iodine concentration,NIC in arterial and venous phases and curve slope in arterial phase of dual-energy between malignant and benign central cervical lymph nodes in thyroid papillary carcinoma.Dual energy CT technology is helpful in identifying of metastatic from non-metastatic small central cervical lymph nodes.