¹⁸F-FDG Diagnostic Efficacy In Iodine Refractory DTC Patients And Association Of Gene Mutations On The Study

Part Ⅰ Systematic evaluation of ¹⁸F-FDG PET/CT diagnostic efficacy in iodine refractory DTC patientsObjective:To systematically evaluate the diagnostic efficacy of ¹⁸F-FDG PET/CT in recurrent differentiated thyroid carcinoma patients with positive Tg and negative ¹³¹I whole-body imaging.Methods:A total of 1009 articles were retrieved from the computer literature database and 16 studies of 1036 patients were included.Meta-statistical analysis was performed using Meta-Disc1.4,RevMan 5.4.1 and STATA₁2.0 to test the heterogeneity between the studies,and draw a comprehensive receiver operating characteristic curve to calculate the area under the curve;.The Z test was used to compare the diagnostic evaluation indexes of PET/CT in the diagnostic iodine scan and therapeutic iodine scan groups,and analyze the difference between the PET/CT evaluation indexes in the stimulated state and the inhibited state under the same iodine scan.Results:The ¹⁸F-FDG PET/CT diagnosis of recurrent DTC patients with positive Tg and negative ¹³¹I whole-body imaging,combined sensitivity was 0.87（95%CI:0.82±0.91）,specificity was 0.79（95%CI:0.68±0.86）,positive likelihood ratio was 3.76（95%CI:2.32±6.09）,negative likelihood ratio is 0.20（95%CI:0.14～0.27）,diagnostic odds ratio is 23.89（95%CI:13.23～43.12）,area under the SROC curve AUC is 0.905,and Q index is 0.837;The Z test showed that there was no statistical difference in the Q index of PET/CT between the diagnostic iodine scan and the therapeutic iodine scan group（P>0.05）,and there was no statistical difference in the Q index of PET/CT between the stimulated state and the inhibited state under the same iodine scans（P>0.05）.Conclusion:¹⁸F-FDG PET/CT has high diagnostic efficiency for recurrent DTC patients with positive Tg and negative ¹³¹I whole-body imaging,and diagnostic iodine scanning.Therapeutic iodine scanning of PET/CT in patients with DTC recurrence have the same diagnostic efficacy.,and diagnostic efficiency of ¹⁸F-FDG PET/CT in stimulated state is not better than that in inhibited state.Part Ⅱ Evaluation of the diagnostic efficacy of ¹⁸F-FDG combined with PET-VCAR for iodine refractory DTC patientsObjective:To explore the relationship between Tg levels under different TSH states and PET-VCAR metabolic parameters MTV,TLG,SUV_mean,SUV_max,SUL_peak in patients with Tg positive and ¹³¹I-Rx-WBS negative DTC recurrence,and combine various metabolic parameters to evaluate the metabolic characteristics and diagnostic efficacy of such patients.Methods:68 patients with Tg positive and ¹³¹-Rx-WBS negative were selected and divided into stimulation group and inhibition group according to different TSH status of the patients.The stimulation group was divided into group A（<20ng/ml）,group B（20～100ng/ml）and C group（>100ng/ml）,the inhibition group was divided into A₁ group（<20ng/ml）,B₁ group（20-100ng/ml）,C₁ group（>100ng/ml）.The general data and metabolic parameters of the stimulation group and the inhibition group were compared by independent sample t-test,χ² test,and Mann-Whitney U test;the two groups with the same Tg level but different TSH status were compared by the Mann-Whitney U test;the three groups with different Tg levels but same TSH status were compared by Kruskal-Wallis H test;the correlation between Tg and various metabolic parameters was analyzed by Spearman;ROC curve and AUC were drawn to evaluate the diagnostic efficacy of each metabolic parameter in patients with DTC recurrence.Results:TSH,Tg,SUV_mean、SUV_max,and SUL_peak in the stimulation group were higher than those in the inhibition group（all P<0.05）;there was no significant difference in the metabolic parameters between the stimulation and inhibition groups at the same Tg level（all P>0.05）;The TLG,SUV_mean,SUV_max and SUL_peak of different Tg levels in the C group and the C₁ group were higher than those in the groups A and B,and the A₁ and B₁ groups（all P<0.05）;There is a positive correlation between Tg and TLG,SUV_mean,SUV_max,and SUL_peak in different states（all P<0.05）;the sensitivity of ¹⁸F-FDG PET/CT in the stimulation and inhibition state groups are 93%,88%,the specificity are 57%,60%,the accuracy are 87%,84%;the AUC of the stimulation state group TLG,SUV_mean,SUV_max,SUL_peak are 0.881,0.893,0.810,0.938;the inhibition state group TLG,SUV_mean,SUV_max,SUL_peak AUC are 0.808,0.896,0.856,0.916.Conclusion:¹⁸F-FDG PET/CT imaging under different TSH states has good diagnostic value for Tg-positive and ¹³¹I-Rx-WBS negative DTC patients with recurrence;Tg has a good positive correlation with TLG,SUV_mean、SUV_max,and SUL_peak,among which SUL_peak has the highest diagnostic efficiency and can more effectively guide clinical follow-up evaluation and treatment.Part Ⅲ A comparative study on the diagnostic efficacy of ¹⁸F-FDG in patients with iodine refractory DTC and its association analysis with rare gene mutation casesObjective:Comparison of the diagnostic efficacy of ¹⁸F-FDG PET/CT between system evaluation and single-center for Tg positive and ¹³¹I-Rx-WBS negative DTC patients,and combine pathological analysis with the association with rare genes.Methods:Search of 1009 articles in the literature database in the past 10 years included 9 studies of 566 in patients with Tg-positive and ¹³¹I post-treatement whole body scan(¹³¹I-Rx-WBS)negative DTC recurrence to judge the diagnostic efficacy of ¹⁸F-FDG PET/CT.A single-center selected 68 such patients from 2017 to 2021,the general data and diagnostic efficacy of single-center patients were compared.The system evaluation group and the single-center group compare the diagnostic efficacy of PET/CT in patients under the same stimulation state and the inhibition state respectively.The system evaluation group and the single-center group compare the diagnostic efficacy of PET/CT in patients with different TSH states and the latter analyzes the influence of different Tg levels and different TSH levels on the evaluation indicators under different stimulus states.The general data of patients with system evaluation and single-center DTC were compared by independent sample T test and independent sample χ² test,and the two diagnostic power evaluation indicators were compared by independent sample χ² test and Fisher’s exact probability test.Search the TCGA gene database,single-center qualitative analysis of the association of rare genes with PET/CT and pathology.Results:System evaluation DTC patients are older than single center（P<0.05）,and the proportion of PTC is lower than single center（P<0.05）;system evaluation ¹⁸F-FDG PET/CT evaluates Tg-positive and ¹³¹I-Rx-WBS negative DTC patients with recurrence SEN,SPE,AC,FPR,FNR,PPV,NPV are respectively 89%,77%,85%,23%,11%,90%,75%,single-center evaluation of SEN,SPE,AC,FPR,FNR,PPV,NPV are 91%,58%,85%,42%,9%,91%,58%.There is no statistical difference in the same TSH status between the system evaluation and single-center groups（all P>0.05）,and there is no statistical difference in the different TSH status between the system evaluation and single-center groups（all P>0.05）.In addition,there were no statistically significant differences in PET/CT diagnostic efficacy evaluation indicators for different Tg levels and different TSH levels in the single-center group（all P>0.05）.TCGA database showed that BRAF mutations were common in DTC,while TERT and DICER1 were rare.When TERT and DICER1 mutations were present,tumor aggressions were stronger and clinical prognosis was poor,and SUV_max was significantly increased.Conclusion:¹⁸F-FDG PET/CT has a higher detection rate of lesions in patients with Tg-positive ¹³¹I-Rx-WBS-negative DTC recurrence in both stimulated and inhibited states,and a higher diagnostic coincidence rate between system evaluation and single-center comparisons.For such patients,PET/CT imaging and related genetic testing should be performed in time to fully guide the follow-up treatment of patients.