The effect of 131I therapy for primary and metastatic lesions of thyroid carcinoma depends on the ability of iodine uptake.The loss or down-regulation of iodine-metabolizing genes represents dedifferentiation of DTC,which results in the disability to take up and accumulate 131I and eventually leads to radioiodine-refractory DTC (RR-DTC).The management of RR-DTC is extremely difficult and the prognosis is poor.It is important for the treatment and prognosis of RR-DTC to investigate the mechanism of redifferentiation.The up-regulation of thyroid iodine-metabolizing genes expression,inhibition of the changes in epigenetic modifications and intervention of the abnormal activation of signaling pathways are reviewed in this article.

Objective To evaluate the influences of FBP and OSEM (with different iteration numbers or subset numbers) on cardiac function parameters with MPI,and to identify a suitable clinical method.Methods The MPI of 66 patients (33 males,33 females,age range: 18-77 years) from January 2012 to December 2014 were retrospectively analyzed.The imaging data was reconstructed with FBP and 5 different OSEM (4-16 subsets and 2-4 iterations) in order to evaluate if there was any difference of cardiac function parameters calculated by QGS between the different image processing methods.In addition,the results were compared with those of cardiac ultrasonography.One-way analysis of variance was used for data analysis.Results The statistical differences of LVEF,EDV,and ESV(F values: 10.73,4.89 and 5.97,all P<0.05) were found among 6 reconstructed methods.The values of LVEF were (66.14±11.12)％,(75.05±12.10)％,(70.09±11.27)％,(66.88±10.38)％,(64.97±10.25)％,and (62.58±9.84)％.Those of EDV were (77.32±27.58),(67.97±27.56),(75.10±27.89),(81.03±28.11),(84.94±29.07),and (89.98±29.71) ml,and the ESV values were (28.71±10.04),(19.71±16.51),(25.13±17.66),(29.01±18.47),(32.10±19.63),and (35.83±20.41) ml respectively.The cardiac function parameters measured by OSEM (with 2 iterations,12 subsets) were much similar to that measured by cardiac ultrasonography.Conclusion Compared with other 5 processing methods of MPI,the OSEM (with 2 iterations,12 subsets) method may be more suitable for practical clinical application.

Objective To investigate the relationship between the initial change of Tg and clinical outcome in DTC patients with pulmonary metastases after 131I treatment.Methods A total of 47 DTC patients (13 males,34 females;average age (41.6±16.3) years) with pulmonary metastases from January 2008 to June 2014 were retrospectively analyzed.Patients were divided into 3 groups according to the variation of Tg: G1 with a declined (more than 50％) Tg;G2 with a declined (less than 50％) Tg or an increased (less than 10％) Tg;G3 with an increased (more than 10％) Tg.The median follow-up time was 1 501 d.Clinical outcomes were divided into remission,stable disease and progressive disease according to the serum test and imaging results.Data analysis was performed by χ2 test and Fisher exact test.Results The percentage of G1,G2,G3 patients was 44.7％(21/47),40.4％(19/47),and 14.9％(7/47) respectively.Results of follow-up showed 19.0％(4/21) patients achieved remission and 81.0％(17/21) with stable disease in G1.There were 2/19 with remission,12/19 with stable disease and 5/19 with progression disease in G2.All patients (7/7) had progressive disease in G3.The clinical outcome was related to the variation of Tg after 131I treatment (Fisher exact test,P<0.01).Conclusions Initial Tg after 131I treatment could be a predictor to the outcome of patients.The increased Tg level indicates a high possibility of 131I refractory disease.

Objective To evaluate the role of 131I SPECT/CT in post-surgical re-staging and recurrence risk stratification in patients with DTC and its impact on subsequent treatment strategy.Methods 131I-WBS and 131I SPECT/CT were performed at the same time 5 to 7 d after 131I treatment in 118 patients (33 males,85 females,average age 45 years) with DTC.Difference in the localization and qualitative diagnosis of 131I uptake lesions between 131I-WBS and 131I SPECT/CT were compared.Value of 131I SPECT/CT in the diagnosis of TNM staging,risk stratification and impact on the treatment strategy was evaluated.Paired χ2 test was used for data analysis.Results A total of 509 foci with 131I uptake were detected.131I-WBS found 449 foci with 131I uptake,354 of which (78.84％) were correctly diagnosed.131I SPECT/CT found 509 foci with 131I uptake,and 504(99.02％) were correctly diagnosed.The difference was statistically significant (χ2=21.51,P<0.01).131I-WBS changed the clinical staging in 13 cases with diagnostic accuracy of 5/13.131I SPECT/CT changed the clinical staging in 19 cases and with diagnostic accuracy of 19/19 (χ2=74.41,P<0.01).131I-WBS changed the risk stratification of 13 patients after operation and the accuracy was 5/13,the corresponding data were 22 and 100％(22/22) for 131I SPECT/CT (χ2=74.41,P<0.01).The treatment strategy was changed in 50 patients with 131I SPECT/CT.Conclusions Compared with 131I-WBS,131I SPECT/CT could provide more accurate positioning and qualitative information for 131I treatment and is more accurate in re-staging and risk stratification.

Objective To evaluate the diagnostic value of the SPM-based interhemispheric asymmetry analysis (SIAA) of 18F-FDG PET brain imaging in localization of temporal lobe epileptic foci.Methods A total of 73 patients (42 males,31 females,average age: (27.10±9.78) years) diagnosed as temporal lobe epilepsy (TLE) and 30 healthy volunteers (17 males,13 females,average age: (33.79±5.46) years) from March 2012 to July 2015 were enrolled in this retrospective study.18F-FDG PET brain imaging was performed on all subjects to localize temporal lobe epileptic foci.The results of 18F-FDG-PET were analyzed by SIAA,visual analysis and asymmetry index (AI) analysis.The accuracy of the three methods was evaluated according to the postoperative pathological results and curative effect.χ2 test and partition of χ2 test were used to analyze the data.Results The accuracies of localization with SIAA,visual analysis and AI analysis were 87.67％(64/73),75.34％(55/73) and 69.86％(51/73),respectively (χ2=6.993,P<0.05).The accuracy of SIAA was higher than that of visual analysis and AI analysis (χ2 values: 5.818 and 8.481,both P<0.017),while there was no significant difference between AI analysis and visual analysis (χ2=0.500,P>0.017).Conclusion The SIAA of 18F-FDG PET brain imaging may be a more objective and accurate method in localization of TLE foci.

Early diagnosis of inflammation and properly interfere to improve the prognosis are very important.However,it is difficult to verify inflammation or differentiate inflammation from infection in clinic,especially in the condition of underlying inflammation.Currently,radiopharmaceuticals based on researches of pathophysiology progress of diseases are studied constantly.This review summarizes the potential inflammation imaging radiotracers and their mechanisms,potential clinical application value.

Objective To prepare 68Ga-PSMA-617 and perform its microPET imaging on both normal BALB/c mice and BGC-823 (PSMA expression) tumor bearing mice.Methods 68GaCl3 was eluted from 68Ge-68Ga generator by 0.05 mol/L HCl,then added to the DKFZ-PSMA-617 and heated at 85 ℃ for 5 min.The labeling efficiency and in vitro stability of 68Ga-PSMA-617 in sodium chloride solution and HAS were analyzed by radio-HPLC.Water partition coefficient and plasma protein binding rate were also evaluated.MicroPET imaging was performed in normal female BALB/c mice and human gastric tumor (BGC-823) bearing mice at 60 min post-injection of 68Ga-PSMA-617.18F-FDG was also injected to BGC-823 tumor bearing mice to acquire microPET imaging for contrast.Results The labeling yield of 68Ga-PSMA-617 was 97.9％,and it could be used directly without purification.68Ga-PSMA-617 showed good in vitro stability in sodium chloride solution and 5％ HAS,the radiochemical purities were 94.9％ and 81.0％ respectively at 80 min post-incubation.68Ga-PSMA-617 was water-solubility substance,and it cleared mainly through the kidneys.MicroPET imaging showed that 68Ga-PSMA-617 could be accumulated in tumor (T/NT=2.28),which was better than 18F-FDG.Conclusions Preparation of 68Ga-PSMA-617 is convenient and has a high labeling yield.It can specifically target to PSMA expression tumors and has a promising prospect in clinical application.

Objective To compare treatment response according to the PERCIST1.0,RECIST1.1,EORTC,and WHO criteria in patients with colorectal liver metastases (CLM) who received neoadjuvant chemotherapy.Methods A total of 41 CLM patients (27 males,average age 68.48 years;14 females,average age 62.43 years) from January 2010 to September 2013 were included in this retrospective study.PET/CT scan was performed before chemotherapy and after 4-6 cycles′ chemotherapy.The baseline and the sequential follow-up 18F-FDG PET/CT of each patient were evaluated according to the PERCIST1.0,RECIST1.1,EORTC,and WHO criteria.The response was categorized into 4 levels including CR,PR,SD,PD.PET/CT images were used for both metabolic and anatomic evaluation.The concurrent diagnostic CT or MRI images (performed within 1 week of PET/CT) were also utilized when needed.The agreements of criteria were analyzed using Kappa test.The response rate (RR) and disease control rate (DCR) were compared using χ2 test.Results The RR and DCR according to the PERCIST1.0,EORTC and RECIST1.1 criteria were 31.71％(13/41) and 63.41％(26/41),31.71％(13/41) and 60.98％(25/41),17.07％(7/41) and 68.29％(28/41),respectively.The general comparison of PERCIST1.0 and RECIST1.1,EORTC and RECIST1.1 criteria showed good agreements (κ values: 0.711,0.689).Significant difference was not found in the DCR(χ2=2.000,P>0.05) but found in the RR(χ2=6.000,P<0.05) between PERCIST1.0 and RECIST1.1.Difference of DCR between EORTC and RECIST1.1 was not significant(χ2=3.000,P>0.05),while the RR had significant difference(χ2=6.000,P<0.05).The RR and DCR according to WHO criterion were 12.20％(5/41) and 70.73％(29/41),which had a good consistency with those according to PERCIST1.0 criteria (κ=0.629).Significant statistical difference was not found in the DCR(χ2=3.000,P>0.05) but found in the RR(χ2=8.000,P<0.05) between PERCIST1.0 and WHO criteria.Conclusions In evaluating CLM treatment response,anatomical criteria and metabolic criteria have a good consistency.But metabolic criteria are more sensitive for RR evaluating.

Objective To investigate the gender differences of glucose metabolic network in brains of healthy adults at resting state by 18F-FDG PET.Methods A total of 204 dextromanual,healthy individuals (104 males,average age:(53.45±11.51) years;100 females,average age:(54.11±12.09) years) were enrolled from June 2011 to June 2016 to construct brain metabolic networks.The nodal and global parameters,including clustering coefficient (Cp),characteristic path length (Lp) and betweenness centrality (Cb),were analyzed by graph theory.Permutation test with 1 000 repetitions was used.Results The brain metabolic networks derived from 18F-FDG PET data were with small-world properties in both male group and female group.Compared with Cb in females,Cb in males was significantly reduced in left postcentral gyrus,right angular gyrus and left temporal pole/middle temporal gyrus (permutation test,all P<0.05);and it was increased in left amygdala,left precuneus,right temporal pole/middle temporal gyrus and left inferior temporal gyrus (permutation test,all P<0.05).Comparing with the females,the male group had higher Cp and longer absolute Lp but without significant difference (permutation test,all P>0.05).Conclusions There are gender-related differences of topological structure in whole-brain metabolic networks.Gender should be considered as a covariate while designing experiments,accounting for cerebral metabolic data from normal control and experimental patients as well as making clinical decisions.

Objective To observe non-displaceable binding potential (BPND) changes of striatal dopamine D2 receptors(SDDR) in patients with first-episode major depressive disorder (MDD) using 11C-Raclopride PET/CT,and to analyze the relationship between BPND and Hamilton rating scale for depression (HAM-D).Methods From December 2014 to December 2015,patients with first-episode MDD and age/gender-matched healthy controls underwent brain MRI and 11C-Raclopride PET/CT in this prospective study.BPND of bilateral SDDR was calculated by molecular imaging and kinetic analysis toolbox (MIAKAT).BPND changes of bilateral SDDR and their relationship with HAM-D score were analyzed.Paired t test,two-sample t test and Pearson correlation analysis were used.Results A total of 20 MDD patients (8 males,12 females,average age: (32.80±9.76) years) and 20 healthy controls (9 males,11 females,average age:(29.25±6.93) years) were enrolled in this study.The 11C-Raclopride uptake in brain tissue of the MDD group and control group were mainly distributed in bilateral striatum,and very few 11C-Raclopride was distributed in bilateral cerebral cortex and cerebellum.In MDD group,the BPND level of bilateral SDDR had no statistical differences(t values: 0.69,0.35,both P>0.05),and similar results were found in the control group(t values: 0.28,0.24,both P>0.05).Compared with the control group,however,the MDD group had lower BPND level of bilateral SDDR(t values: 3.13-4.41,all P<0.05).The BPND of bilateral caudate nucleus and/or putamen D2 receptors was correlated with HAM-D total score,anxiety/somatization factor score,cognitive impairment factor score,retardation factor score and sleep disturbance factor score(r values: from-0.688 to-0.453,all P<0.05).Conclusions The binding potential of SDDR in patients with first-episode MDD is declined,and the BPND level of SDDR is correlated with symptoms of depression.The abnormality of SDDR may be an important molecular mechanism of the abnormality of midbrain-striatal dopamine reward circuits in MDD patients.