Abstract:

Objective To investigate the clinical value of imaging features of primary lesions combined with venous phase CT value in predicting central group lymph node （LN） metastasis in patients with papillary thyroid carcinoma （PTC）. Methods Clinical data of 170 PTC patients who underwent central group LN dissection in the First People's Hospital of Handan City of Hebei Province from January 2017 to June 2020 were retrospectively analyzed. All patients were divided into different groups according to whether central group LN metastasis or not， and there were 89 patients with central group LN metastasis and 81 patients without central group LN metastasis. The CT value and imaging features of primary lesions in different periods were analyzed， and the imaging features of primary lesions combined with venous phase CT values to predict the central group LN metastasis were evaluated by the receiver operating characteristic （ROC） curve. Results There were no statistically significant differences in CT value in plain scan phase and CT value， net increased CT value， standardized CT value in arterial phase between patients with and without central group LN metastasis （all P>0.05）. The CT value， net increased CT value and standardized CT value in venous phase of patients with central group LN metastasis were （113.84±22.95） HU， （59.05±12.10） HU and 0.72±0.14 respectively， which were significantly higher than those of patients without central group LN metastasis [（103.99±17.67） HU， （51.29±14.45） HU and 0.59±0.10]（t=3.26， P<0.001； t=3.81， P<0.001； t=3.67， P<0.001）. ROC curve analysis showed that the area under the curve for diagnosing central group LN metastasis of PTC patients was 0.75， 0.70 and 0.76 when the cut-off values of CT value， net increased CT value and standardized CT value in venous phase were 115.78 HU， 62.37 HU and 0.75 respectively. There were statistically significant differences in the diameter of primary focus and the contact area of thyroid capsule between patients with and without central group LN metastasis （Z=-2.34， P=0.019； Z=-2.08， P=0.037）. There were no statistically significant differences between calcification and primary lesion location （both P>0.05）. Lesion diameter >2 cm （87.73%） and capsule contact range ≥1/2 （92.17%） had the highest specificity in predicting central group LN metastasis. The imaging features of primary lesion combined with standardized CT value in venous phase was in good agreement with histopathological diagnosis results in predicting central group LN metastasis （Kappa=0.475）， and the sensitivity and specificity were 73.12% and 82.75% respectively. Conclusion The imaging features of the primary lesion combined with CT value in venous phase have a good clinical value in predicting central group LN metastasis in PTC patients. Patients with primary lesion diameter >2 cm， capsule contact range ≥1/2 and the standardized CT value in venous phase >0.75 are more likely to have central group LN metastasis.

Key words: Thyroid neoplasms, Lymphatic metastasis, Tomography， spiral computed