The Relationship Research Between Pre-Ablative ^99mTc-Pertechnetate Scintigraphy And Therapeutic Response To Radioiodine Remnant Ablation In Patients With Differentiated Thyroid Cancer

Objectives:surgery and postsurgical ¹³¹I remnant ablation?RRA?is the major treatment of differentiated thyroid carcinoma?DTC?.In consideration of the long-term prognosis of patients with DTC,prediction of the therapeutic response to RRA is particularly important,and pre-ablative ^99mTc-pertechnetate scintigraphy is simple and easy to operate,and will not affect the effectiveness of RRA.The aim of this study is to investigate the relationship between pre-ablative ^99mTc-pertechnetate scintigraphy and therapeutic response to RRA.Methods:Retrospectively collected the postsurgical DTC patients with RRA in Nuclear Medicine of the First Affiliated Hospital of China Medical University between March2016 and October 2016 and meet the inclusion criteria.Pre-ablative ^99mTc-pertechnetate scintigraphy was performed before the RRA,firstly the plane image of pre-ablative^99mTc-pertechnetate scintigraphy was qualitative analyzed into positive or negative by visual analysis method,then the patients with positive result got the remnant thyroid tissue mass trough the calculation formula of hyperthyroidism.After routinely follow-up6-12 months,according to the therapeutic response assessment system proposed by 2015American Thyroid Association?ATA?guidelines,the therapeutic response was assessed into excellent response?ER?,indeterminate response?IDR?,biochemical incomplete response?BIR?and structural incomplete response?SIR?,then divided into ER group and non-ER group.Comparison the statistical differences of factors(age,gender,frequency of surgery,surgical procedure,qualitative result of pre-ablative ^99mTc-pertechnetate scintigraphy,pre-ablative stimulated Tg level,et al.)between the ER and the non-ER groups by univariate analysis method,then these factors with statistical differences were analyzed by multivariate analysis method;then the relationship between the remnant thyroid tissue mass in positive pre-ablative ^99mTc-pertechnetate scintigraphy and the therapeutic response to RRA was further studied.Univariate analysis use Mann-Whitney test,multivariate analysis use Binary Logistic regression,rate comparison use chi-square test.P<0.05 means statistically significant.Results:A total of 167 DTC patients were collected,there were 39?23.40%?male and128?76.60%?female patients,with a mean age of 42.14±12.55 years.Pre-ablative^99mTc-pertechnetate scintigraphy was positive in 77 patients?46.10%?and negative in 90?53.90%?patients.Excellent response?ER?,indeterminate response?IDR?,biochemical incomplete response?BIR?and structural incomplete response?SIR?was demonstrated in64?38.30%?,62?37.10%?,31?18.60%?,10?6%?,respectively.Univariate analysis showed that,between ER and non-ER group distant metastasis,the qualitative results of pre-ablative ^99mTc-pertechnetate scintigraphy,pre-ablative serum TgAb level and the therapeutic dose of ¹³¹I were statistical differences?Z=-2.951,-3.021,-3.968,-3.108,P=0.003,0.003,0.000,0.002?,while age,gender,the frequency of surgery,surgical procedure,relapse risk stratification,the time when Tc-99m pertechnetate scintigraphy was performed,qualitative results of ultrasound,pre-ablative sTg level,pre-ablative stimulated serum TSH level,the time interval between surgery and RRA treatment and qualitative results in Tx-WBS were not statistical differences?all P>0.05?,multivariate analysis revealed that the qualitative results of pre-ablative ^99mTc-pertechnetate scintigraphy?odds ratio[OR]:3.193,95%confidence interval[CI]:1.500-6.795,P=0.003?was the independent risk factors of the therapeutic response to RRA.Further chi-square test showed that the rate of ER between different groups of the remnant thyroid tissue mass exited statistical difference??²=4.696,P=0.030?,and when the remnant thyroid tissue mass less than 2.19g,the rate of ER?63.20%?was higher.Conclusions:The qualitative result of pre-ablative ^99mTc-pertechnetate scintigraphy is the independent risk factor of the therapeutic response to RRA,can be used to predict the therapeutic response to RRA,and the therapeutic response of the patients with positive^99mTc-pertechnetate scintigraphy is better than the negative ones.Meanwhile,when the remnant thyroid tissue mass of the positive ones less than 2.19g,the rate of ER is higher.