The Clinical Value Of Serum Tg,TgAb And Comparative Imaging In The Assessment Of Differentiated Thyroid Carcinoma After ¹³¹I Therapy

ObjectiveTo study the clinical value of thyroglobulin (Tg), a therapeutic dose 131I-whole body scan (131I-WBS), thyroglobulin antibody (TgAb), ultrasound of the neck and the chest CT in the diagnosis of recurrence or metastasis of differenttided thyroid carcinoma (DTC).Methods:One hundred sixty patients with DTC (with or without concomitant neck dissection) after surgical treatmeat and 131I radiotherapy were enrolled in the study. Before they were applied with 131I again,stop taking levothyroxine tablets of 2 to 4 weeks with TSH increasing to> 30 mIU/L, serum Tg and TgAb levels,the cervical ultrasonic examination and the chest CT were performed,then 131I-whole body scan were performed 5 to7 days after 131I radiotherapy.The diagnosis of whether the patients have recurrence or metastasis of thyroid cancer is mainly based on primarily on surgical pathology, laboratory tests, imaging studies, and clinical follow-up, etc. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of Tg, 131I-WBS, ultrasound of the neck,the chest CT and both of them in the diagnosis of DTC recurrence or metastasis were calculated. Analyze the clinical value of TgAb in the diagnosis of DTC recurrence or metastasis.Results:(1) In 160 cases of enrolled patients:86 cases of positive serum Tg,74 cases of negative serum Tg,97 cases of 131I-WBS-positive,63 cases of 131I-WBS-negative.113 cases of the 160 patients were diagnosed DTC recurrent or metastatic in the final clinical diagnosis.(2) The sensitivity of Tg and 131I-WBS in diagnosis of DTC recurrence or metastasis were 71.7% and 84.1%,the specificity were 89.4% and 95.7%, the accuracy were 76.9% and 87.5%, the positive predictive value were 94.2% and 97.9%, and the negative predictive value were 56.8% and 71.4%,respectively.The total sensitivity, total specificity, total accuracy, total positive predictive value and the total negative predictive value of Tg combined with 131I-WBS were 91.2%,85.1%,89.4%,93.6% and 80%,respectively.(3) The ratio of DTC recurrence or metastasis of patients with TgAb≥40IU/mL was significantly higher in patients with TgAb<40IU/mL, the difference between the two groups was statistically significant (P<0.05).(4) The sensitivity of the ultrasound of the neck and 131I-WBS in diagnosis of recurrence or metastasis of cervical lymph nodes of DTC were 84.7% and 77.6%, the specificity were 65.3% and 100%, the accuracy were 75.6% and 88.1%, the positive predictive value were 73.4% and 74.3%, the negative predictive value were 79% and 90.6%, respectively. The total sensitivity, total specificity, total accuracy, total positive predictive value and the total negative predictive value of the ultrasound of the neck combined with 131I-WBS were 95.3%,65.3%,81.3%,74.3% and 90.6%,respectively.(5) The sensitivity of the chest CT and 131I-WBS in diagnosis of lung metastasis of DTC were 80.6% and 83.4%, the specificity were 91.5% and 100%,the accuracy were 89.4% and 96.9%, the positive predictive value were 69.4% and 100%, the negative predictive value were 95.2% and 96.3%, respectively. The total sensitivity, total specificity, total accuracy, total positive predictive value and the total negative predictive value of the chest CT combined with 131I-WBS were 93.5%,91.5%, 91.8%,96.7% and 98.3%, respectively.Conclusion:The testing of Serum Tg and 131I-WBS are the most commonly used methods in the follow-up of DTC patients.The sensitivity of the combination Tg with 131I-WBS in the diagnosis of DTC recurrent or metastatic is up to 91%, significantly higher than a single diagnosis. The TgAb can be used as a indicator in the follow-up of DTC patients. The ultrasound of the neck in diagnosis of cervical lymph node metastasis of DTC, the chest CT in the diagnosis of lung metastasis of DTC, have a certain sensitivity and specificity, and have an important clinical significance in the follow-up of DTC patients after 131I therapy.