| BackgroundRadiation damage of salivary gland is one of the side effects of 131I treatment in patients with differentiated thyroid carcinoma(DTC).The main manifestations are swelling and pain.When the damage is serious,xerostomia,dental caries and even dysphagia may occur.Some studies have shown that acid stimulation can accelerate salivary secretion and reduce the residence time of radioactive iodine,which can alleviate the disease to a certain extent.However,some scholars have also proposed that acid stimulation can increase local blood perfusion and increase the absorption of radioactive iodine in salivary glands.So far,there is no consensus on whether acid stimulation has a real protective effect on salivary glands.Acid stimulation is simple and easy to implement,and it is still a hot spot in clinical research.Vitamin C(VitC)is one of the most studied methods.Quantification is one of the main advantages of nuclear medicine imaging.In recent years,the hardware platform and algorithm technology of single photon emission computed tomography/computed tomography(SPECT/CT)equipment have made great progress,realizing the accurate quantification of SPECT/CT.In the study of xSPECT Quant,some scholars found that there is a certain correlation between the standardized uptake value(SUV)and thyroid function.Salivary Gland Scintigraphy(SGS)with 99mTcO4-as a tracer is a mature objective examination to assess salivary gland function,but there is no relevant research on the quantitative determination of salivary glands by SPECT/CT so far.Based on the fact that both thyroid and salivary glands can uptake 99mTcO4-,this study combined Quantitative SPECT/CT with SGS in order to achieve a double assessment of thyroid and salivary gland functions.Purpose1.To explore the effect of VitC on parotid gland function after 131I treatment in DTC patients.2.Additional analysis of technetium uptake capacity of DTC patients’ residual thyroid gland from a quantitative perspective.MethodsIn a prospective study,60 patients with DTC who received 150mci of 131I after the first surgery were enrolled from June 2020 to October 2020,First,44 patients with DTC were included in the VitC group,which began to take VitC tablets 2 hours after 131I treatment(200mg/time,3 times/day for 1 week).Then,16 patients with DTC were included in the control group,and no special treatment was required after 131I treatment.Record the patient’s clinical data,including gender,age,thyroid-stimulating hormone(TSH),free triiodothyronine(FT3),free thyroxine(FT4),24h maximum absorption iodine rate,etc.During the hospitalization,the patients’salivary gland swelling,pain and other symptoms were followed up and recorded.Quantitative SPECT/CT combined with SGS were performed in both groups one day before 131I treatment and 1.5～2 months after 131I treatment.The images and time activity curve(TAC)were analyzed,and the uptake index(UI)and maximum secretory ratio(MSR)of bilateral parotid glands were calculated.Simultaneously outline the volume of interest(VOI)on the three sections to obtain the maximum standardized uptake value(SUVmax)and average standardized uptake value(SUVavg)of the bilateral parotid glands and residual thyroid.According to the results of the first SGS,all patients were divided into normal function group and impaired function group.The functional parameters between the different intervention groups within the two functional groups are compared separately.Use SPSS25.0 to perform statistical analysis on the obtained data.The correlation between the two quantitative data is mainly analyzed by spearman correlation analysis,the quantitative data is represented by M(P25,P75),and the non-parametric Wilcoxon signed rank sum test of paired samples is used for intra-group comparison.The Mann-Whitney U test of two independent samples was used for the comparison between groups,and the χ2 test was used for the comparison of qualitative data,p<0.05 was considered statistically significant.Results1.Symptoms:the incidence of acute salivitis in the acid stimulation group was 15.91%,the incidence of acute salivitis in the non-acid stimulation group was 29.5%.2.The relationship between parotid function and parotid SUV:parotid UI and MSR are correlated with SUVmax and SUVavg respectively,UI has a stronger correlation with SUVmax and SUVavg,with correlation coefficients of 0.525 and 0.637 respectively.3.Normal function group:there was no significant difference in parotid function and SUV value between the VitC group and the control group(p>0.05).In the intra-group comparison,only the SUVmax of bilateral parotid glands in VitC group after treatment was higher than those before(p<0.05),while there was no significant difference in the functional parameters of the control group(p>0.05).4.Function impaired group:compared with the control group,only the ΔMSR of bilateral parotid gland in VitC group was higher(p<0.05).When comparing within groups,the UI,MSR,SUVavg of the bilateral parotid glands and the SUVmax of the left parotid glands after treatment in the VitC group were higher than those before(p<0.05),and SUVmax of the right parotid gland also reached a critical level(p=0.05),while there was no significant difference in the functional parameters of the control group(p>0.05).5.Quantitative determination of residual thyroid tissue in the neck:the 24h maximum iodine uptake rate of the residual thyroid tissue imaging group was higher than that of the residual thyroid tissue without imaging group(p<0.05).There was a correlation between SUVmax of residual thyroid tissue and the highest iodine uptake rate within 24h,and the correlation coefficient was 0.381.Conclusion1.VitC has a protective effect on the salivary glands:sublingual VitC 2 hours after 131I treatment in DTC patients(200mg/time,3 times/day)can reduce the incidence of acute salivitis and promote the recovery of parotid gland function.2.Quantitative SPECT/CT has a good application prospect:in a certain sense,the quantitative determination of residual thyroid can replace the determination of 24-hour iodine uptake function in patients with DTC. |
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