Abstract:
Objective To explore the value of the quantitative parameters of dual-energy CT iodine map combined with morphological signs in predicting cervical central lymph node metastasis (CLNM) in papillary thyroid microcarcinoma (PTMC).
Methods Clinical and imaging data of 165 patients with PTMC diagnosed by postoperative histopathology and who underwent central lymph node dissection in Yunnan Cancer Hospital, the Third Affiliated Hospital of Kunming Medical University from January 2020 to December 2020 were retrospectively analyzed. The cohort included 51 males and 114 females, aged 22–69 (47.8±13.9) years old. The patients were divided into the CLNM and non-CLNM groups according to the histopathological results. Morphological signs of the lesions, including multiple lesions, long diameter, irregular shape, microcalcification, thyroid edge contact, and blurred boundary after enhanced scanning, were evaluated. The iodine concentration (IC) and CT value of the PTMC lesions in the arteriovenous phase were measured by dual-energy CT scanning before the operation. The normalized IC (NIC) and normalized CT (NCT) value of the lesions in the arteriovenous phase were calculated. Independent sample t-test was used to compare the IC, NIC, CT, and NCT values of the arteriovenous lesions between the two groups. χ2 test was used to compare the morphological signs of lesions between the two groups. A receiver operator characteristic curve (ROC) was drawn for the morphological signs and quantitative parameters of the dual-energy CT iodine map with statistically significant differences in univariate analysis, and the area under curve (AUC) was calculated. Binary stepwise logistic regression was used to obtain the joint prediction coefficient of the quantitative parameters and the morphological signs.
Results Significant differences were found in the multiple lesions, lesion diameter, irregular shape, and thyroid edge contact between the two groups (χ2=7.298–12.422, all P<0.01), and thyroid edge contact had the highest diagnostic efficiency for cervical CLNM(AUC=0.695). The NIC and NCT values of the CLNM group were higher than those of the non-CLNM group in the arteriovenous phase, and the differences were statistically significant (0.36±0.02 vs. 0.32±0.03, 0.70±0.11 vs. 0.59±0.10, 0.43±0.06 vs. 0.37±0.07, 0.81±0.08 vs. 0.75±0.12; t=4.248–8.301, all P<0.01). The NIC in the arterial phase had the highest diagnostic efficiency for cervical CLNM(AUC=0.822), and the optimal cut-off value was 0.36. The quantitative parameters of the dual-energy CT iodine map combined with the morphological signs had the highest diagnostic efficiency for cervical CLNM, with AUC of 0.908, sensitivity of 86.70%, and specificity of 75.10%. Thyroid edge contact was an independent risk factor for cervical CLNM.
Conclusion The quantitative parameters of dual-energy CT iodine map combined with the morphological signs exhibited important clinical value in predicting cervical CLNM of patients with PTMC before an operation.