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Objective:To explore the relation of the radiochemical purity and in vivo imaging effect of 68Ga-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (DOTA)- D-phe1-Tyr3-Thr8-octreotide (TATE) injection. Methods:High performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) methods were established to determine 68Ga-DOTATATE, 68Ga 3+ , 68Ga in colloidal form and 68Ga-DOTA- D-Phe1-Tyr3-Thr8-dethreonine-octreotide (heptapeptide) and to study the influence of precursor purity on radiochemical purity of labelled products. The uptake of 68Ga-DOTATATE injection with different radiochemical purities was investigated in nude mice bearing AR42J cells by microPET imaging and the tumor target/non-target (T/NT) value was calculated. One-way analysis of variance and Pearson correlation analysis were used to analyze the data. Results:The contents of 68Ga 3+ and 68Ga in colloidal form were not related with precursor purity ( r values: 0.385, 0.497, P values: 0.306, 0.137), while the content of 68Ga-DOTA-heptapeptide was positively related with the purity of DOTA-heptapeptide ( r=0.957, P<0.001). The radiochemical purities of 68Ga-DOTATATE injection were (87.0±2.3)%, (86.8±0.8)% and (94.0±3.1)% when the DOTATATE purities were 90.9%, 91.6% and 99.2%, respectively. The results of microPET imaging showed that the tumor uptake was positively related with the radiochemical purity of 68Ga-DOTATATE injection ( r=0.828, P<0.001), and the T/NT values of 68Ga-DOTATATE injection with radiochemical purities of 95.7%, 85.8%, 84.5% and 79.9% were 21.25±8.84, 8.50±1.51, 11.38±1.65 and 6.01±0.99, respectively ( F=11.48, P=0.001). Conclusion:The radiochemical purity of 68Ga-DOTATATE injection is impacted by the purity of labelled precursor and manufacturing processes and is related with the imaging effect in vivo.
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Objective:To prepare 68Ga-fibroblast activation protein inhibitor (FAPI)-04, and evaluate its biodistribution and imaging characteristics in animals and healthy volunteers, in order to investigate the clinical translation potential. Methods:68Ga-FAPI-04 was synthesized by a manual method and its radiolabeling yield, radiochemical purity, and stability ( in vivo and in vitro) were analyzed. ICR mice ( n=16) were scarified at 5, 30, 60 and 120 min postinjection of 68Ga-FAPI-04 (1.11 MBq) to measure radioactive counts in main organs. The dynamic mircoPET imaging was acquired for 60 min on 3 ICR mice, and tumor imaging capabilities were examined with nude mice bearing HepG2 tumors. Furthermore, 2 healthy volunteers (1 male with age of 64 years, 1 female with age of 56 years) were recruited for the investigation of probe biodistribution in humans. A serial whole-body dynamic PET/CT scan was performed immediately following injection. Results:68Ga-FAPI-04 was synthesized within 20 min with the radiochemical yield of (68.7±4.0)% (decay corrected). The radiochemical purities of 68Ga-FAPI-04 were over 99% and the products were stable for 180 min in vitro and for 90 min in blood. 68Ga-FAPI-04 was mainly cleared through urinary tracts, while other organs only showed mild tracer accumulation. MicroPET imaging showed high uptake of 68Ga-FAPI-04 in the tumor tissue of mice, and the ratio of tumor/liver was 2.14±0.01 (35 min). The PET/CT imaging results of healthy volunteers revealed 68Ga-FAPI-04 could be quickly cleared. Conclusion:68Ga-FAPI-04 has many advantages for PET imaging, such as easy labeling, good stability, quick clearance and low background signals in the liver, which can be used as an attractive PET tracer for detection hepatocellular carcinoma.
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Objective To prepare 2-[18F]fiuoropropionic acid (18F-FPA) and evaluate its biodistribution and imaging capacity in Lewis lung carcinoma-bearing mice.Methods 18F-FPA was prepared by nucleophilic substitution reaction,and its hydrophilicity was analyzed.18F-FPA (7.4-11.1 MBq) was injected into Lewis lung carcinoma-bearing mice via tail vein.MicroPET imaging was performed at 20,80 min after the injection.The biodistribution of 18F-FPA in organs was analyzed.The blocking effects of sodium propionate and dichloroacetate to 18F-FPA were tested in vivo.Data were analyzed by two-sample t test using GraphPad Prism software.Results The synthesis of 18F-FPA took 40 min.18F-FPA had high radiochemical purity (＞99％) and hydrophilicity.18F-FPA was mainly distributed in the carcinoma,the urinary bladder and the caecum.The radioactive uptakes in muscles,brown fat and bones were relatively low.Quantitative analysis showed that the uptake of 18F-FPA in Lewis lung carcinoma from 20 min to 80 min was slightly increased ((17.03±2.87) ％ID/g vs (19.33±2.45) ％ID/g) without significant difference (t=1.100,P＞0.05).Neither sodium propionate nor dichloroacetate could block the uptake of 18F-FPA in Lewis lung carcinoma (t=1.544,0.894;both P＞0.05).Conclusions 18F-FPA can be quickly synthesized and has good physicochemical properties.It can be used as a tracer to visualize Lewis lung carcinoma in mice,and its tumor uptaking can not be blocked by propionate and dichloacetate.18 F-FPA PET has the potential to detect lung cancer noninvasively in clinic.
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Objective To investigate the value of 18 F-fluorodeoxyglucose (18 FDG)positron emission tomography and computer tomography (PET/CT)in the diagnosis and localization of ectopic ACTH syndrome (EAS)induced by lung cancer,and to increase the accuracy rate of diagnosis of EAS.Methods 8 patients were histopathologically proven to be lung cancer.18 FDG PET/CT wholebody and brain scan were performed;magnetic resonance imaging (MRI),99m Tc-octreotide (OCT)imaging and inferior petrosal sinus sampling (IPSS)were done in all patients.On 18 FDG PET/CT images,the SUVmax values of lesions and the SUVmax ratio of lesion tissue to normal lung tissue were calculated.Results ① 8 patients with EAS included 2 cases of carciniod,4 cases of atypical carciniod,and 2 cases of small cell lung cancer.The ACTH levels in inferior petrosal sinus and peripheral veins of 8 patients had no difference.②The chest CT showed there were pulmonary nodules in 6 cases (75%),among them 2 cases were atypical lesions.5 cases of pituitary adenomas were found by MRI (25%),and OCT imaging was positive in 2 cases (25%).③The 18 FDG PET/CT showed nodular,mass like or patch samples with high metabolic activity in 8 cases (100%)of pulmonary lesions.The SUVmax of tumor was 0.72 to 14.05 (3.67±4.68),and the ratio of SUVmax of lesion tissue to normal lung tissue was 1.69 to 27.54 (8.14 ± 9.63).18 FDG hypermetabolism was found in 8 cases of bilateral adrenal hyperplasia,while 4 cases showed pituitary tumor.Conclusion Lung cancer is a common source of EAS,especially carcinoid.18 FDG PET may show lower glucose metabolism.18 FDG PET/CT should be used as an assisted method to diagnose EAS.
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Objective To synthesize 68 Ga-1,4,7,10-tetraazacyclododecane-N,N',N,N()-tetraacetic acid-D-Phe1-Tyr3-Thr8-octreotide (68Ga-DOTATATE) manually and automatically,validate its qualities in vitro,and evaluate its biodistribution in ICR mice and the microPET imaging in nude mice bearing pancreatic AR42J tumor.Methods 68Ga-DOTATATE was synthesized by automatic method using commercial metal isotope multifunctional module with strong cation exchange (SCX) column and by manual method.Both the products were measured for quality control.For the biodistribution study 5 groups of ICR mice were injected with 68Ga-DOTATATE(1.11 MBq) and executed at 10,30,60,120 and 240 min postinjection,respectively.The organs were weighted,and ％ ID/g was calculated.Nude mice bearing pancreatic AR42J tumor were intravenously injected with 3.7 MBq 68Ga-DOTATATE,and then microPET imaging was acquired at 10,30,60,120,18 and 240 min.Results 68Ga-DOTATATE could be successfully synthesized by the automatic and manual methods.Both the product injections were colorless and clear.The pH value was 6.5±0.1.For the products obtained from the two methods,the radiochemical purities were over 99％,and the products were stable for 4 h at room temperature.For the automatic method,68Ga-DOTATATE was synthesized within 30 min and with the radiochemical yield of (51.8±3.2)％ (time decay corrected).For the manual method,the time used for the synthesis was 20 min,and the labeling yield was over 99％.Three batches of the products were aseptic and pyrogen-free.In ICR mice,68Ga-DOTATATE was excreted by the kidney,and showed relatively high accumulation in the liver,spleen,pancreas and adrenal glands,while lower in the bone and soft tissue.The clearance from blood was fast with (4.41±0.81) ％ID/g at 10 min postinjection and (0.78 ± 0.32) ％ ID/g at 1 h.MicroPET imaging showed increased uptake of 68GaDOTATATE in the tumor tissues,and T/NT were 2.01±0.29(10 min),6.74±2.90(30 min) and 4.46±2.05 (60 min),respectively.Conclusions 68 Ga-DOTATATE could be successfully synthesized manually and automatically.The products reach to the specification of radioactive drugs and could be used as an attractive positron emitting radiotracer for detection of the somatostatin receptor-positive tumors.
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Objective To label the modified human epidermal growth factor receptor 2 (HER2) affibody with 68Ga at cysteine position of carboxyl-terminal Gly-Gly-Gly-Cys (GGGC) sequence,and to image the mice model bearing HER2-expressed breast cancer with microPET.Methods The HER2 affibody with carboxyl-terminal cysteine was produced by gene engineering.The 1,4,7,10-tetraazacyclododecane-1,4,7-tris-aceticacid (DOTA) was conjugated to the thiol (SH)-group of cysteine by DOTA-10-maleimidoethylacetamide (MMA-DOTA).The newly eluted 68Ga was labeled to DOTA-HER2 affibody at 90 ℃.The labeled mixture was purified by C18 cartridge and eluted with anhydrous alcohol.The purified 68Ga-labeled affibody was prepared for cell binding analysis and microPET imaging.The HER2-expressed breast cancer cells MBA-MD-361 were used to analyze cell binding and establish cancer model with BALB/c nude mice.68Ga-labeled affibody (3.7 MBq) was administered to 4 nude mice with breast cancer via tail vein for microPET imaging at 20 and 60 min post injection.The mice were sacrificed immediately after imaging in unconscious state and their tissue/organs (tumor,muscle,bone and heart) were removed for weighing and radioactivity counting by γ counter.The tumor to normal organ ratios of radioactivity (tumor to liver,muscle,bone and heart)were calculated.Results The purity of HER2 affibody was more than 95％.The radiochemical purity of 68Ga-labeled HER2 affibody was 97％.The KD value (affinity) of 68Ga-labeled HER2 affibody was 1.5 nmol/L in HER2positive cells.MicroPET imaging showed that 68Ga-labeled HER2 affibody could bind HER2-positive cancer rapidly and excreted mainly through urinary system.The radioactivity ratios of tumor to liver,muscle,bone and heart were 17.4±1.0,35.1±10.9,20.7±6.2 and 20.9±4.0,respectively.Conclusions 68Ga could be labeled to HER2 affibody.The 68Ga-labeled HER2 affibody may be useful for PET imaging of HER2-positive tumor.