Multi-parametric MRI combined with 68Ga-PSMA PET/CT for the diagnosis of clinically significant prostate cancer / 中华核医学与分子影像杂志

Objective:To explore whether multi-parametric MRI (mpMRI) combined with 68Ga-prostate specific membrane antigen (PSMA) PET/CT can improve the detection efficiency of clinically significant prostate cancer (csPCa). Methods:Clinical and imaging data of 152 patients (age (68.5±8.5) years) who underwent mpMRI and 68Ga-PSMA PET/CT examination for suspected prostate cancer in the First Affiliated Hospital of the Air Force Medical University from January 2021 to November 2022 were retrospectively analyzed, with the histopathological results from transrectal ultrasound guided biopsy as reference. Lesions with Gleason scores (GS) ≥3+ 4 from the biopsy were diagnosed with csPCa, and lesions with negative biopsy or GS 6 were diagnosed with non-csPCa. MpMRI was evaluated independently by two radiologists according to the Prostate Imaging Reporting and Data System (PI-RADS) version 2.1. The radioactive uptake of 68Ga-PSMA PET/CT in prostate lesions was evaluated by SUV max. The independent-sample t test, Mann-Whitney U test and χ2 test were used to compare differences between the two groups, and then multivariate logistic regression analysis was performed. ROC curves analysis was used to analyze the diagnostic efficacies of individual and combined factors and Delong test was used. Results:There were 85 csPCa and 67 non-csPCa confirmed. Prostate specific antigen (PSA), PI-RADS score and SUV max were significantly different between the csPCa group and the non-csPCa group ( χ2=68.06, U values: -7.66, -8.98, all P<0.001). Multivariate logistic regression analysis indicated that PI-RADS score (odds ratio ( OR)=3.424, 95% CI: 1.651-7.100) and SUV max ( OR=1.931, 95% CI: 1.403-2.658) were independent predictors of csPCa (both P<0.001). ROC curves analysis revealed that the cut-off value for diagnosing csPCa was 4 for PI-RADS score and 5.6 for SUV max. The accuracy of mpMRI and PET/CT alone in csPCa diagnosis was 80%(122/152) (AUC of 0.789(95% CI: 0.711-0.866) with the sensitivity and specificity of 91%(77/85) and 67%(45/67)), and 87%(132/152) (AUC of 0.876(95% CI: 0.817-0.936) with the sensitivity and specificity of 81%(69/85) and 94%(63/67)), respectively. Several joint models incorporating 68Ga-PSMA PET/CT with mpMRI data were investigated, the model of PI-RADS 5 or PI-RADS 3-4 and SUV max>5.6 showed better performance than mpMRI and PET/CT alone and other joint models ( z values: 2.01-3.64, all P<0.05), with the accuracy of 91%(138/152) (AUC of 0.910(95% CI: 0.857-0.962) with the sensitivity and specificity of 89%(76/85) and 93%(62/67)). Conclusion:MpMRI combined with 68Ga-PSMA PET/CT can significantly improve the detection efficiency of csPCa, with the principal effect being improved in risk stratification of PI-RADS 3-4 lesions in mpMRI.

Synthesis and biological evaluation of 68Ga-NOTA-CD44: a novel tracer targeting atherosclerotic plaques / 中华核医学与分子影像杂志

Objective:To construct 68Ga-1, 4, 7-trizacyclononane-1, 4, 7-triacetic acid (NOTA)-CD44 as a novel atherosclerosis tracer targeting hyaluronic acid (HA), and evaluate its biological property and molecular imaging features. Methods:Low molecular weight (LMW) recombinant human CD44 protein was selected, and the C-terminal of the protein was modified by sulfonation and coupled to the bifunctional ligand NOTA to synthesize a novel molecular probe 68Ga-NOTA-CD44 targeting HA. The biological properties of the probe, such as labeling rate and in vitro stability, were studied. Three atherosclerotic plaque model mice and three normal C57BL/6 mice were studied by 68Ga-NOTA-CD44 microPET/CT imaging and pathological examination. Results:68Ga-NOTA-CD44 tracer was synthesized and purified with the radiochemical purity above 99%, and the specific activity was up to 62.22 MBq/nmol. lts stability was good in PBS, and the radiochemical purity was over 90% after incubation for 3 h. After intravenous injection, the probe was metabolized mainly by the kidneys, and its metabolic level decreased successively in the liver, lungs and blood. MicroPET/CT imaging results of atherosclerotic model mice suggested that the uptake in the plaque of abdominal aorta was higher at 60 min after injection, with SUV max and target/background ratio (TBR) max of 1.14±0.02 and 4.95±0.93, and the probe had certain atherosclerotic plaque eroded targeting, which was consistent with the pathological result. Conclusions:As a novel probe, 68Ga-NOTA-CD44 is simple to prepare and has a high labeling rate. It has good physicochemical properties and in vivo biological properties, and can display atherosclerotic eroded plaques sensitively. 68Ga-NOTA-CD44 has a promising prospect to be a new molecular probe for early noninvasive recognition of atherosclerotic eroded plaques.

Discrimination of cultivation modes of Dendrobium nobile based on content of mineral elements and ratios of nitrogen stable isotopes / 中国中药杂志

This study explored the feasibility of mineral element content and ratios of nitrogen isotopes to discriminate the cultivation mode of Dendrobium nobile in order to provide theoretical support for the discrimination of the cultivation mode of D. nobile. The content of 11 mineral elements(N, K, Ca, P, Mg, Na, Fe, Cu, Zn, Mn, and B) and nitrogen isotope ratios in D. nobile and its substrate samples in three cultivation methods(greenhouse cultivation, tree-attached cultivation, and stone-attached cultivation) were determined. According to the analysis of variance, principal component analysis, and stepwise discriminant analysis, the samples of different cultivation types were classified. The results showed that the nitrogen isotope ratios and the content of elements except for Zn were significantly different among different cultivation types of D. nobile(P<0.05). The results of correlation analysis showed that the nitrogen isotope ratios, mineral element content, and effective component content in D. nobile were correlated with the nitrogen isotope ratio and mineral element content in the corresponding substrate samples to varying degrees. Principal component analysis can preliminarily classify the samples of D. nobile, but some samples overlapped. Through stepwise discriminant analysis, six indicators, including δ~(15)N, K, Cu, P, Na, and Ca, were screened out, which could be used to establish the discriminant model of D. nobile cultivation methods, and the overall correct discrimination rates after back-substitution test, cross-check, and external validation were all 100%. Therefore, nitrogen isotope ratios and mineral element fingerprints combined with multivariate statistical analysis could effectively discriminate the cultivation types of D. nobile. The results of this study provide a new method for the identification of the cultivation type and production area of D. nobile and an experimental basis for the quality evaluation and quality control of D. nobile.

Causes of False-Positive Results in 68Ga-Labeled Fibroblast Activation Protein Inhibitor PET/CT Imaging / 中国医学科学院学报

Objective To investigate the causes of false-positive results in the 68Ga-labeled fibroblast activation protein inhibitor (68Ga-FAPI-04) PET/CT imaging. Methods The imaging data of 547 patients undergoing 68Ga-FAPI-04 PET/CT examination in the Department of Nuclear Medicine of the Affiliated Hospital of Southwest Medical University from September 2020 to May 2021 were retrospectively collected.Two experienced nuclear medicine diagnostic physicians analyzed the clinical data,relevant imaging examinations,laboratory examinations,pathological results and follow-up results of the patients with false-positive results. Results The 68Ga-FAPI-04 PET/CT imaging of 547 patients showed false-positive results in 99 (18.1%) patients,including 56 males and 43 females.The postoperative pathological examination confirmed false-positive results in 13 patients,including 1 patient of thyroiditis,2 patients of pulmonary tuberculosis,1 patient of bone tuberculosis,2 patients of pulmonary inflammatory pseudotumor,1 patient of pulmonary sarcoidosis,1 patient of pulmonary benign fibroma,1 patient of organic pneumonia,2 patients of renal angiomyolipoma,1 patient of mass pancreatitis,and 1 patient of pancreatic mucinous cystadenoma.The medical history,relevant imaging examination,and long-term follow-up confirmed false-positive results in 86 patients.Specifically,the false-positive uptake in the neck,chest,abdomen,bone joint,and skin occurred in 8 (9.3%),13 (15.1%),5 (5.8%),57 (66.3%),and 3 (3.5%) patients,respectively.Inflammation-related uptake appeared in 83 (83.8%) patients with false-positive imaging results,of which arthritis (23 patients) and osteophyte (29 patients) were the most common.Sixteen (16.2%) patients showed the false-positive uptake related to fibroblasts. Conclusion 68Ga-FAPI-04 PET/CT imaging will show non-malignant tumor false-positive results,which are mainly associated with inflammation and fibroblasts.

Safety and efficacy of 177Lu-DOTATATE for neuroendocrine neoplasms / 中华核医学与分子影像杂志

Objective:To explore the efficacy and adverse effects of 177Lu-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid- D-Phe1-Tyr3-Thr8-octreotide (DOTATATE) in patients with neuroendocrine neoplasms (NEN). Methods:From 2019 to June 2021, 36 patients (26 males, 10 females; age (43.5±12.9) years) with metastatic NEN who were treated with 177Lu-DOTATATE in the Affiliated Hospital of Southwest Medical University were retrospectively analyzed. Toxicities were assessed by using the common terminology criteria for adverse events (CTCAE) version 5.0. Disease progression and tumor response were determined according to the response evaluation criteria in solid tumors (RECIST) version 1.1. Prognostic factors for progression-free survival (PFS) and overall survival (OS) were analyzed by Cox proportional-hazards model. Results:Of 36 patients, the median follow-up time was 19.8 months, the median PFS was 24 months, and the median OS was not reached. The WHO grade Ⅲ (hazard ratio ( HR)=3.59, 95% CI: 1.10-11.73, P=0.025; OS: HR=7.85, 95% CI: 1.50-41.10, P=0.004), 18F-FDG positive (PFS: HR=3.05, 95% CI: 1.04-8.93, P=0.033; OS: HR=5.90, 95% CI: 1.04-33.49, P=0.025), and received systemic chemotherapy before peptide receptor radionuclide therapy (PRRT) (PFS: HR=2.79, 95% CI: 1.01-7.73, P=0.039; OS: HR=5.56, 95% CI: 1.01-30.57, P=0.026) were prognostic factors for PFS and OS. Transient side effects included fatigue (27.8%, 10/36), nausea (5.6%, 2/36), and the most common laboratory toxicities were lymphocytopenia (11.1%, 4/36), followed by mild renal toxicity (8.3%, 3/36) and mild liver injury (5.6%, 2/36). Conclusions:PRRT with 177Lu-DOTATATE is an effective and well-tolerated treatment in patients with NEN. PFS and OS are shorter in patients who are WHO grade Ⅲ NEN, 18F-FDG positive, and received systemic chemotherapy before PRRT.

Application value of 68Ga-PSMA-11 PET/CT in newly diagnosed prostatic cancer patients / 中华核医学与分子影像杂志

Objective:To explore the value of 68Ga-prostate specific membrane antigen (PSMA)-11 PET/CT in newly diagnosed prostate cancer patients with different risk stratifications, and to compare the performance of this modality with conventional imaging in detecting metastases. Methods:From June 2019 to July 2020, the clinical and imaging data of 60 patients (age range: 44-88 years, median age 69 years) who underwent 68Ga-PSMA-11 PET/CT imaging in Fudan University Shanghai Cancer Center were retrospectively analyzed. Spearman rank correlation analysis was used to explore the correlation of SUV max in primary foci with prostate specific antigen (PSA) and Gleason score (GS). Based on the D′Amico risk stratification (PSA>20 μg/L and ≤20 μg/L, GS>7 and ≤7), the detection rates of 68Ga-PSMA-11 PET/CT for metastases were evaluated by χ2 test, and the differences of SUV max were analyzed by Mann-Whitney U test. Patients were divided into high-risk (PSA>20 μg/L and GS>7), medium-risk (PSA>20 μg/L and GS≤7, or PSA≤20 μg/L and GS>7), and low-risk (PSA<20 μg/L and GS<7) groups according to PSA levels and GS. Compared with conventional imaging (bone imaging, CT or MRI), the ability of 68Ga-PSMA-11 PET/CT to detect metastatic tumors, and the utility to change the prostate cancer stage were evaluated by Fisher′s exact test. Results:High uptake of 68Ga-PSMA-11 was observed in primary lesions of 60 patients, and SUV max was positively correlated with GS or PSA ( rs values: 0.42, 0.38; P values: 0.001, 0.002). The detection rates of lymph node and bone metastases in the group with PSA>20 μg/L were 11/18 and 13/18, respectively, which were higher than those in the group with PSA≤20 μg/L (28.57%(12/42) and 35.71%(15/42); χ2 values: 6.56, 7.56, P values: 0.010, 0.006. However, there was no statistical significance in the SUV max of these lesions( z values: -1.04, -0.96; P values: 0.299, 0.337). There was a statistical difference in the detection rates of lymph node and bone metastases between the group with GS>7 and the group with GS≤7 (lymph node: 54.05%(20/37) vs 13.04%(3/23), χ2=10.09, P=0.001; bone metastases: 59.46%(22/37) vs 26.09%(6/23), χ2=8.19, P=0.004), as well as the SUV max of bone metastases( z=-2.02, P=0.044). In the high-risk group, 68Ga-PSMA-11 PET/CT had the higher detection rate of metastases than conventional imaging (16/17 vs 10/17; P=0.039) and it changed 25.0%(15/60) of the patients′ staging. Conclusions:PSA and GS affect the detection rate of 68Ga-PSMA-11 PET/CT. In patients with high-risk prostate cancer, 68Ga-PSMA-11 PET/CT is superior to conventional imaging in detecting metastases. When PSA>20 μg/L and GS>7, it is better to use 68Ga-PSMA-11 PET/CT in prostate cancer staging.

Preparation of 89Zr-labeled mesenchymal stem cells and PET monitoring in mice with systemic lupus erythematosus / 中华核医学与分子影像杂志

Objective:To label mesenchymal stem cells (MSCs) with 89Zr-oxine complex, and assess its characteristics of PET imaging in systemic lupus erythematosus (SLE) model (MRL/lpr mice). Methods:SLE mice were screened by 18F-FDG PET imaging. 89Zr-oxine was prepared and used for labeling MSCs (10 6 MSCs and 1 MBq 89Zr-oxine). 89Zr-oxine-labeled MSCs (0.2 MBq) were injected into MRL/lpr mice and BALB/c mice (each n=5) via tail vein at a dose of 1.2×10 6 cells per mouse, and followed with microPET imaging in vivo at 2 h, 6 h, 1 d, 3 d, 7 d, 10 d and 14 d after injection. The percentage activity of injection dose per gram of tissue (%ID/g) was calculated. Independent-sample t test was used to analyze the data. Results:MSCs was successfully labeled with 89Zr-oxine, with the labeling efficiency of 20% and cell viability >90%. MicroPET imaging showed that MSCs were mainly distributed in lungs and the liver sites at 2 h after injection. The number of MSCs homing to kidneys of MRL/lpr mice ( n=5) increased significantly 24 h after the injection, and the renal uptake of MSCs in MRL/lpr mice was much higher than that in BALB/c mice ((8.28±1.27) vs (4.33±0.94) %ID/g; t=3.54, P=0.024). The renal uptake increased firstly and then decreased and then leveled off, indicating MSCs homing to kidneys. Conclusions:A method for 89Zr-oxine labeling of MSCs is successfully established. 89Zr-labeled MSCs can home to kidneys of SLE mice. PET imaging of 89Zr-labeled MSCs can be effectively used to explore the in vivo distribution and migration behavior of transplanted MSCs during the treatment of diseases such as SLE.

ImmunoPET studies of 64Cu-labeled CD30 monoclonal antibody 64Cu-NOTA-CD30 in lymphoma models / 中华核医学与分子影像杂志

Objective:To develop the anti-CD30 monoclonal antibody 64Cu-1, 4, 7-trizacyclononane-1, 4, 7-triacetic acid (NOTA)-CD30 and visualize CD30 expression in lymphoma non-invasively. Methods:The CD30 expression levels of 5 cell lines (Karpas299, Raji, Daudi, Ramos, and U266) were assessed by Western blot. Cell lines with high and low CD30 expression were selected for flow cytometry to evaluate the specific binding affinity of anti-CD30 monoclonal antibody. Thirteen NSG mice were used to established CD30 positive and negative subcutaneous xenograft models. 64Cu-NOTA-CD30 was obtained and 64Cu-NOTA-immunoglobulin (Ig)G was used as the control. ImmunoPET imaging was performed 2, 24, and 48 h after the injection of 64Cu-NOTA-CD30 or 64Cu-NOTA-IgG. Finally, the biodistribution studies were conducted. Repeated-measures analysis of variance and Bonferroni test were conducted for comparison. Results:Karpas299 showed the highest CD30 expression, while Raji showed the lowest. Flow cytometry showed specific binding affinity of the anti-CD30 monoclonal antibody to the Karpas299 cell line. The radiochemical purities of the probes were both higher than 95%. In microPET, the 64Cu-NOTA-CD30 uptake of Karpas299 xenograft tumors increased over time, with (11.46±0.58), (17.60±1.16) and (19.46±0.99) percentage activity of injection dose per gram of tissue (%ID/g) at 2, 24 and 48 h respectively. The contrast to normal tissue was good at 48 h, with the tumor/heart (blood) ratio of 2.20±0.22. The uptake of 64Cu-NOTA-CD30 in Karpas299 tumor at 48 h after injection was significantly higher than that in Raji tumor ((6.10±1.03) %ID/g) and 64Cu-NOTA-IgG in Karpas299 tumor ((5.12±0.89) %ID/g; F=290.99, t values: 19.65 and 22.25, all P<0.001). The uptake of 64Cu-NOTA-CD30 and the control probe in the heart and liver decreased over time in all groups. Ex vivo biodistribution at 48 h was mainly consistent with the results of microPET in vivo. Conclusions:64Cu-NOTA-CD30 is able to visualize the expression level and distribution of CD30 non-invasively. It is promising to be applied for screening the beneficial groups and evaluating efficacy for CD30-targeted immunotherapy.

Optimization of labeling methods for a novel prostate cancer PET probe Al 18F-PSMA-137 / 中华核医学与分子影像杂志

Objective:To investigate the effects of different labeling conditions on the yield of Al 18F-labeled 1, 4, 7-triazacylononane-1, 4, 7-triaceticacid (NOTA)-prostate specific membrane antigen (PSMA)-137, and to determine the experimental condition for obtaining Al 18F-PSMA-137 probe in high yield. Methods:The effects of different pH values, buffer systems (acetic acid-sodium acetate buffer system and potassium hydrogen phthalate (KHP) buffer system), AlCl 3-ligand ratios, ligand amounts, ethanol volumes and reaction temperatures on the labeling rate were investigated in detail. Results:The pH value of the reaction solution had a significant effect on the labeling rate, and the optimal range was 4.0-4.5. When the pH value was higher than 4.5, the labeling rate decreased significantly. Both the acetic acid-sodium acetate buffer system and the KHP buffer system could be used to label NOTA-PSMA-137 with Al 18F, and the KHP buffer system obtained higher labeling rate. The ratio of AlCl 3-ligand affected the labeling rate, and the highest labeling rate could be obtained when the ratio of AlCl 3-ligand was 0.54-0.62. When the ratio of AlCl 3-ligand was fixed, increasing the amount of ligand could improve the labeling yield. Adding hydrophilic organic solvent ethanol to the reaction system could significantly increase yield, with the highest labeling rate being achieved at a volume of 100 μl ethanol. The most suitable reaction temperature was 100 ℃, and when the temperature raised to 110 ℃, the labeling rate decreased significantly. The most suitable labeling conditions for NOTA-PSMA-137 were as following: 25 μl KHP buffer (0.50 mol/L, pH=4.0), 7.0 μl AlCl 3 solution (20 mmol/L), 200 μl Na 18F solution (74-80 MBq) and 230 μg ligand NOTA-PSMA-137 were mixed in a vial, then stood for 5 min and 100 μl ethanol was added, and all reagents were heated at 100 ℃ for 10 min. The yield of Al 18F-PSMA-137 under above conditions were 85.7%-88.5%. Conclusion:Optimization of labeling condition can improve the yield of Al 18F-PSMA-137 and the stability of the labeling.

Evaluation of the effect of linker on novel targeted PSMA PET probe / 中华核医学与分子影像杂志

Objective:To prepare a novel targeted prostate specific membrane antigen (PSMA) molecular probe Al 18F-PSMA-136, and evaluate the effects of the change in linker on the biological behavior and tumor targeting ability. Methods:Al 18F-PSMA-136 was prepared by replacing the phenyl of Al 18F-PSMA-137 with cyclohexyl in 1, 4, 7-triazacylononane-1, 4, 7-triaceticacid (NOTA). The inhibition abilities of PSMA of NOTA-PSMA-136 and NOTA-PSMA-137 were determined by N-acetylated-α-linked acidic dipeptidase (NAALADase) method. The radiochemical purity and in vitro stability of the labeled products were analyzed by radio-high-performance liquid chromatography. The PSMA specificity and tumor targeting capability of the probes were investigated in 22Rv1 (PSMA positive-expressing) cells and mouse models. Independent-sample t test was used to analyze the data. Results:The Ki values of NOTA-PSMA-136 and NOTA-PSMA-137 were 3.41 and 0.30 nmol/L, respectively. The labeling yield of Al 18F-PSMA-136 was (30.1±8.4)% and the specific activity was (18.7±5.3) GBq/μmol. The radiochemical purities of the two probes were both greater than 95% and the stabilities in vitro were both good. Both probes showed PSMA-specific in 22Rv1 cells, but the uptake of Al 18F-PSMA-137 was significantly higher than that of Al 18F-PSMA-136 (1 h: (1.67±0.24) vs (1.00±0.01) percentage injected activity per 1×10 5 cells (%IA/1×10 5 cells): t=4.78, P=0.003; 2 h: (2.11±0.06) vs (1.03±0.06) %IA/1×10 5 cells; t=19.90, P<0.001). MicroPET/CT imaging showed that Al 18F-PSMA-136 and Al 18F-PSMA-137 had similar distribution in vivo, mainly concentrated in kidneys, intestine, gallbladder, bladder and tumor. However, the uptake of Al 18F-PSMA-137 in tumor was significantly higher than that of Al 18F-PSMA-136 (1 h: 1.78±0.10 vs 0.54±0.08; t=13.29, P<0.001; 2 h: 1.95±0.01 vs 0.52±0.11; t=18.53, P<0.001). Conclusion:Changes in the NOTA-conjugated linker can significantly affect the PSMA inhibition ability and tumor targeting, and the imaging effect of Al 18F-PSMA-137 with strong lipophilicity is superior.

Establishment and clinical verification of brain template for analyzing 11C-CFT PET imaging data / 中华核医学与分子影像杂志

Objective:To establish standard spatial brain template and ROIs template of 11C-methyl- N-2β-carbomethoxy-3β-(4-fluorophenyl)tropane (CFT) PET images for automated quantitative analysis of dopamine transporter (DAT) distribution. Methods:From May 2014 to December 2015, 11C-CFT PET and MRI T 1 brain images of 16 healthy volunteers (3 males, 13 females; age (63.3±6.9) years) from Huashan Hospital, Fudan University were co-registered and smoothed using statistical parametric mapping(SPM)5 software based on MATLAB to create a standard spatial brain template. The ROIs template was established by ScAnVp procedures. These templates were clinically verified by using 11C-CFT PET images of 37 healthy volunteers (23 males, 14 females; age (61.7±7.1) years), 32 Parkinson′s disease (PD) patients (20 males, 12 females; age (61.1±5.4) years), 10 multiple system atrophy with predominant parkinsonism (MSA-P) patients (7 males, 3 females; age (60.8±7.1) years) and 10 progressive supranuclear palsy (PSP) patients (5 males, 5 females; age (58.4±6.1) years) from Huashan Hospital, Fudan University between January 2014 and March 2019. One-way analysis of variance was used to analyze data. Results:Based on the 11C-CFT PET images and MRI T 1 images of healthy volunteers, a standard spatial brain template for normalization of 11C-CFT PET images was created. The ROIs template was established including seven regions: bilateral caudate, anterior putamen, posterior putamen (along the long axis) and the occipital cortex. The ROIs template was accurately aligned in each verification group. The normal reference values of semi-quantitative DAT distribution in caudate, anterior putamen and posterior putamen were obtained (1.84±0.13, 2.18±0.16, 1.77±0.11). The semi-quantitative values of 11C-CFT uptake in each ROI in patients were significantly lower than those in healthy volunteers ( F values: 49.79-283.83, all P<0.05). Conclusion:The established brain templates with accurate spatial alignment for 11C-CFT image analysis can provide foundational tools for the application of 11C-CFT PET imaging in clinical practice and scientific research.

Research progress on isotope-exchange-based 18F-labeling methods / 中华核医学与分子影像杂志

The application of isotope exchange can realize radiolabeling in partially aqueous media, proceed under mild reaction conditions, and exclude complex purification procedure. It is suitable for one-step labeling of sensitive biomolecules with clinical application potential. This review systematically introduces the 18F/ 19F isotope exchange reactions based on carbon and those non-carbon-based reaction centers including silicon, boron, phosphorus, sulfur, gallium and iron. Discussions of the effects on isotope exchange radiochemical yields and molar activities by different reaction types, and labeling conditions and substitute groups on classic labeled substrate are held where possible, as well as recent applications in using these methodologies to develop PET probes.

Preliminary application evaluation of polydopamine nano-carriers labeled with multiple radionuclides / 中华核医学与分子影像杂志

Objective:To prepare nanoprobes by using polydopamine (PDA) as a carrier which is modified with the sonosensitizer protoporphyrin Ⅸ (PpⅨ) and labeled with 131I, 99Tc m or 177Lu, and to explore the value of these new nanoprobes in diagnosis and combination therapy of breast cancer. Methods:PDA particles were synthesized by aqueous oxidation, and a layer of polyethylene glycol (PEG) and PpⅨ were modified on the surface to product PDA-PEG-PpⅨ. Then the nuclides 131I, 99Tc m and 177Lu were labeled on PDA, respectively, and the labeling yield and stability were determined. The cytotoxicity test was conducted by comparing the viabilities of 4T1 tumor cells in free 131I group and 131I-PDA-PEG-PpⅨ group. The 4T1 cells were divided into 7 groups according to different treatment methods: PDA-PEG-PpⅨ group, PDA-PEG-PpⅨ+ photothermal therapy (PTT) group, PDA-PEG-PpⅨ+ sonodynamic therapy (SDT) group, 131I-PDA-PEG-PpⅨ+ PTT group, 131I-PDA-PEG-PpⅨ+ SDT group, 131I-PDA-PEG-PpⅨ+ PTT+ SDT group (100 μg/ml PDA-PEG-PpⅨ, 925 kBq/ml 131I), and the control group (DMEM culture medium). The cell viabilities of those groups were compared to evaluate the therapeutic effect. 4T1 tumor bearing mouse models were established, then 99Tc m-PDA-PEG-PpⅨ was injected through the tail vein (29.6 MBq) or intratumorally (14.8 MBq) to perform gamma imaging. The independent-sample t test and one-way analysis of variance were used for data analysis. Results:The PDA particles were uniform in size, with a particle size of (160.0±1.5) nm. They had a good photothermal conversion effect. A characteristic peak consistent with PpⅨ (400 nm) appeared in the UV-Vis absorption spectrum of PDA-PEG-PpIX. In the cytotoxicity test, when the radioactivity was 1.850 or 3.700 or 7.400 MBq/ml, the cell viabilities of free 131I group and 131I-PDA-PEG-PpⅨ group were significantly different ((72.18±6.57)% vs (86.07±5.17)%, (59.31±9.06)% vs (80.85±4.21)%, (42.90±1.30)% vs (72.99±5.73)%; t values: 3.71, 4.82, 11.46, P values: 0.006, 0.001, <0.001). The 131I-PDA-PEG-PpⅨ+ PTT+ SDT combination therapy had a better killing effect on 4T1 tumor cells than the combination of 131I-PDA-PEG-PpⅨ+ PTT and 131I-PDA-PEG-PpⅨ+ SDT (cell viabilities: (10.09±2.50)% vs (16.04±2.63)%, (28.65±4.72)%; F=351.66, P<0.001). In vivo imaging showed that 99Tc m-PDA-PEG-PpⅨ was stable in mouse models and could be effectively enriched in tumors. Conclusions:A multifunctional nanoprobe based on PDA is successfully prepared. The radionuclide labeling method is simple and effective, with a good stability. 131I-PDA-PEG-PpⅨ can kill 4T1 cells efficiently. 99Tc m-PDA-PEG-PpⅨ has an obvious tumor concentration effect in mouse models.

Study of 68Ga-NODAGA-RGD PET/CT in predicting short-term efficacy of tyrosine kinase inhibitor in the treatment of distant metastatic differentiated thyroid cancer / 中华核医学与分子影像杂志

Objective:To investigate the clinical application of 68Ga-cyclo( L-arginylglycyl- L-α-aspartyl- D-tyrosyl-N6-(((4, 7-bis(carboxymethyl)-1, 4, 7-triazonan-1-yl)acetyl))- L-lysyl) (NODAGA-RGD) PET/CT to evaluate short-term efficacy of tyrosine kinase inhibitor (TKI) in distant metastatic differentiated thyroid cancer (dmDTC). Methods:From October 2019 to March 2023, 13 dmDTC patients (5 males, 8 females; age: 68(65, 69) years) from Nanjing First Hospital were retrospectively enrolled, of which 9 were clinically confirmed as radioactive iodine-refractory differentiated thyroid cancer (RAIR-DTC) and 4 were dmDTC without radioactive iodine treatment. All patients underwent 68Ga-NODAGA-RGD PET/CT to assess neovascularization of the target lesions (TL), and the SUV max and target background ratio (T/B) were recorded. After 3 months of TKI treatment (anrotinib ( n=9) or apatinib ( n=4)), change rates of the maximum diameter of TL and thyroglobulin (Tg) were measured. The correlation of SUV max, T/B and the change rate of the maximum diameter of TL were analyzed by Spearman rank correlation analysis. ROC curve analysis was performed for the effectiveness of the T/B and TKI therapy, and the difference of the remission rate of lesions was analyzed by Fisher exact test. Results:In 13 patients, 36 TL were measured by 68Ga-NODAGA-RGD PET/CT with SUV max of 5.44(3.43, 7.56) and T/B of 5.25(4.50, 7.23). The change rate of the maximum diameter of TL was -30%(-39%, -21%) and the change rate of Tg was -68%(-96%, -52%). T/B was negatively correlated with the change rate of the maximum diameter of TL after TKI therapy ( rs=-0.46, P=0.005), while SUV max was not correlated with the change rate of the maximum diameter of TL ( rs=0.03, P=0.883). ROC curve analysis showed that the optimal cut-off value for T/B was 4.95, with the AUC of 0.698, the sensitivity of 87.5%, and the specificity of 60.0%. Compared to lesions with T/B<4.95, those with T/B≥4.95 showed higher remission rate (2/14 vs 63.6%(14/22); P=0.006). After 3 months of TKI treatment, the disease control rate was 12/13. Conclusion:68Ga-NODAGA-RGD PET/CT can effectively reflect tumor neovascularization, predict efficacy of TKI therapy, and provide powerful imaging evidence for TKI therapy in dmDTC.

68Ga production with cyclotron solid target and automated synthesis of 68Ga labeled drugs / 中华核医学与分子影像杂志

Objective:To produce 68Ga and automatically synthesize 68Ga-labeled drugs based on low-energy medical cyclotron solid target system. Methods:68Zn was electroplated on the surface of the target by electrodeposition. According to the principle of 68Zn(p, n) 68Ga nuclear reaction, 68Zn was irradiated by the 10 MeV medical cyclotron solid target system (30 μA, 30 min) to produce 68Ga, and the activity, nuclear purity, half-life and content of metal impurities of purified product were determined. 68Ga-prostate specific membrane antigen (PSMA)-11 and 68Ga-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid- D-Phe1-Tyr3-Thr8-octreotide (DOTATATE) were synthesized automatically using 68Ga respectively, and the quality control analyses of drug properties, concentration, pH, radiochemical purity, sterility and bacterial endotoxin were carried out. Results:The electroplating mass of 68Zn was (43.71±0.87) mg ( n=35), the yield of 68Ga after irradiation was (10.96±0.67) GBq ( n=35), and the measured half-life was (67.64±0.06) min ( n=7). Only 511 keV energy peak was detected by the gamma spectrometer. After purification, (6.85±0.12) GBq ( n=35) of pure 68Ga was obtained, and the purification efficiency was (62.46±0.96)% (non-attenuated correction, n=35). The metal impurity contents of Zn and Fe were (0.18±0.06) and (1.25±0.43) μg/GBq ( n=5), which met the requirements of European Pharmacopoeia. Three batches of 68Ga-PSMA-11 and 68Ga-DOTATATE were automatically synthesized, with the yield, concentration and radiochemical purity of (3.54±0.14) and (2.74±0.20) GBq, (294.97±11.58) and (228.17±16.32) GBq/L, (99.73±0.11)% and (99.45±0.25)%, respectively. Both sterility and bacterial endotoxin were qualified. Conclusion:High-yield and qualified nuclide 68Ga and 68Ga-labeled drugs are successfully prepared through the low-energy medical cyclotron solid target system and the automated purification and synthesis module, which provide a strong guarantee for clinical practice.

Automatic radiolabeling of the norepinephrine transporter targeted tracer 18F-mFBG and evaluation of 18F-mFBG PET/CT imaging in pheochromocytoma / 中华核医学与分子影像杂志

Objective:To fulfill the automatic radiolabeling of the norepinephrine transporter (NET) trancer 18F-meta-fluorobenzylguanidine (mFBG), and explore the 18F-mFBG PET/CT imaging effect of pheochromocytoma. Methods:On the basis of the chemical structure of mFBG, a spirocyclic iodonium ylide was used as the precursor to undergo a 3-step reaction sequence (radiofluorination, deprotection and neutralization) on AllinOne synthesis module. Purification by high performance liquid chromatography and formulation were conducted to generate 18F-mFBG. The corresponding quality control tests of 18F-mFBG product was performed. Afterwards, a postoperative patient with pheochromocytoma underwent 18F-mFBG PET/CT imaging. Results:The radiosynthesis was accomplished within 70 min, and 18F-mFBG was obtained in (17.8±2.4)% non-decay-corrected radiochemical yield ( n=5), with radiochemical purity >97% and molar activity >59.2 GBq/μmol. Sterility test, bacterial endotoxins test, abnormal toxicity test and the acetonitrile residue all met the requirements of Pharmacopoeia of the People′ s Republic of China (2020 Volume Ⅳ). The 18F-mFBG PET/CT imaging disclosed high uptake in pheochromocytoma and clear localization of lesions. Conclusions:The automatic radiolabeling of the NET targeted tracer 18F-mFBG is successfully realized by commercially available synthesis module, and the production quality meets all requirements for clinical translation. 18F-mFBG has a potential to image neuroendocrine lesions in clinical setting.

Estimation of atmospheric environmental radiation capacity in an isotope industrial park / 中国辐射卫生

Objective To study and estimate the public dose constraint and the atmospheric radiation capacity of an isotope industrial park, and to provide a basis for management of radioactive effluent discharge in isotope industrial parks. Methods We collected the natural environment data, meteorological data, and population distribution and dietary data as well as the source terms of radioactive airborne effluents of an isotope industrial park. The public dose constraint value of the isotope industrial park was determined based on the natural environmental radiation hazard level. The atmospheric environmental radiation capacity of the industrial park was estimated by the all-pathways method. Results The public dose constraint value of the industrial park was 0.2 mSv/a. At the end of industrial park planning, the maximum individual effective dose to the public caused by airborne effluent discharge was 1.07×10−6 Sv/a, which accounted for 0.54% of the public dose constraint value. The proportions of discharges of airborne radionuclides to respective environmental radiation capacities ranged from 0.04% to 4.34%. Conclusion The determined public dose constraint value of the isotope industrial park can be used as the total radiation capacity of the regional atmospheric environment to constrain the discharge of radioactive effluents. The environmental radiation capacity of each radionuclide can be estimated by the all-pathways method considering the comprehensive impact of radionuclide discharges, which is suitable for the control and management of isotope production enterprises in industrial parks.

Taking the mechanism of glucose catabolism disorder in depression as an example to explore the research ideas and strategies of stable isotope tracer metabolomics / 药学学报

Stable isotope tracer metabolomics tracks and analyzes the whole metabolic process of the body through the tracer atoms, which belongs to the frontier technology in the field of biomedicine. This technology is of great significance and value for explaining the pathogenesis of diseases, finding biomarkers of diseases and drug action targets. Taking the mechanism of glucose catabolism disorder in depression as an example, this paper systematically expounds the stable isotope tracer metabolomics technology and its application. The research idea of stable isotope tracer metabolomics based on unmarked metabolomics was put forward, and the research strategy of biological significance interpretation from four dimensions of metabolite isotope abundance, key metabolic enzymes, metabolic flow direction and metabolite flow was given, which broke through the bottleneck of stable isotope tracer metabolomics research technology based on overall animal experiment, and provided scientific basis for the promotion and application of this technology.

Determination of deuterium incorporation of new drug donafenib tosilate by two methods of LC-MS with natural isotope abundance correction and 1H NMR relative quantitative method / 药学学报

An LC-MS method with natural isotope abundance correction and a 1H NMR relative quantitative method were established to determine the deuterium incorporation of donafenib tosilate, a new deuterated drug molecule. First, the peak areas of isotopic impurities (non-deuterated and incompletely deuterated impurities) and deuterated drug were recorded through the single ion monitoring (SIM) mode of the established LC-MS method and then corrected in terms of the natural isotope abundance offered by ChemDraw soft, removing the nature isotope interference from 13C, 37Cl, etc. The corrected areas were subsequently used to calculate mol% of isotopologues (D0, D1, D2, D3) and Atom% D, namely, deuterium incorporation. In addition, a 1H qNMR experiment was conducted with the aromatic proton at δ 8.63 and the residual proton of isotopic impurities at δ 2.79 as quantitative peaks. The mixture of DMSO-d6 and D2O (10∶1) was employed as the solvent to change the spin-coupling between the residual proton and active hydrogen so that the residual proton could be measured as the single peak, and the sensitivity was greatly improved. The acquisition parameters were also optimized, and Atom% 1H and the deuterium incorporation were then calculated. The two methods were applied to samples of three commercial batches, and the testing results were almost consistent. Both methods proved accurate, sensitive, fast and independent of standard substances and accurate weighing, which could be applied to the determination of the deuterium incorporation of donafenib tosilate and provide a reference for other deuterated drugs.

Global progress in peptide radiopharmaceutical research and China's opportunities / 药学学报

Radiopharmaceutical is an essential component of nuclear medicine and molecular imaging, as well as a key component of precision medicine. The United States Food and Drug Administration (FDA) has recently approved the marketing of several peptide-based radiopharmaceuticals, sparking a global trend of research in this area and propelling nuclear medicine into the precision theranostic era. This has created a new wave of technological competition in the field of nuclear medicine. It is the responsibility of Chinese scientists in the radiopharmaceutical field to capitalize on this opportunity, leverage the momentum, and strengthen their independent innovation capability in order to stay ahead in the future global nuclear science and technology competition. This review provides an overview of the remarkable progress made in the research, development, and translation of global peptide-based radiopharmaceuticals. It examines the advantages of peptide-based radiopharmaceuticals and outlines the current hot targets and progress in drug development in this field. Additionally, it proposes six opportunities for China to overtake others in the field of peptide-based radiopharmaceuticals and achieve technological self-reliance, based on interdisciplinary collaboration and independent innovation. Lastly, the future prospect of peptide-based radiopharmaceuticals is discussed.