To investigate the value of single photon emission computed tomography (SPECT/CT) and serum stimulated state thyroglobulin (sTg) levels in predicting the risk of lymph node metastasis in patients treated with ¹³¹I after thyroid cancer surgery.

The clinical data of 87 patients with thyroid cancer treated with 131I after surgery from June 2018 to June 2021 were retrospectively analyzed. According to whether cervical lymph node metastasis occurred after iodine treatment, they were divided into metastatic group (n=28) and non-metastatic group (n= 59). SPSS 22.0 statistical software was used to process the data, ROC curve was used to analyze the value of the initial dose of ¹³¹I treatment and serum sTg level in predicting the occurrence of lymph node metastasis in patients, and unconditional Logistic stepwise regression was used to analyze the risk factors for the occurrence of lymph node metastasis in patients. The value of SPECT/CT combined with serum sTg levels in predicting the risk of lymph node metastasis in patients treated with ¹³¹I after thyroid cancer surgery was analyzed with consistency. P < 0.05 was considered statistically significant.

Compared with the non-metastatic group, the proportion of patients with tumor diameter > 1 cm, multiple lesions, bilateral lesions, SPECT/CT positive was higher in the metastatic group, and the level of sTg was higher (P < 0.05). The serum sTg≥5.268 ng/ml was the best truncation values for lymph node metastasis in patients treated with 131I after thyroid cancer surgery (P < 0.05). Tumor diameter > 1 cm, multiple lesions, bilateral lesions, SPECT/CT positive, serum sTg≥5.268 ng/ml were risk factors for lymph node metastasis in patients treated with 131I after thyroid cancer surgery (P < 0.05). SPECT/CT combined with serum sTg level had high value in predicting lymph node metastasis in patients treated with 131I after thyroid cancer surgery, with sensitivity of 0.966 and specificity of 0.932.

Lymph node metastasis in patients treated at 131I after thyroid cancer surgery is affected by tumor diameter, number of lesions. Serum sTg≥5.268 ng/ml is the best cut-off value for lymph node metastasis in patients, and SPECT/CT combined with serum sTg has high diagnostic value.