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Background: [18F]Flurpiridaz is a promising novel cardiac PET imaging tracer formed by the radiolabeling of pyridaben derivative with fluorine-18. Clinical studies on [18F]Flurpiridaz are currently at the phase III level for the assessment of MPI. Providing high image quality thanks to its relatively long half-life, F-18 is a high-potential radionuclide for the early detection of CAD. In this study, we aimed to develop a fully automated synthesis of [18F]Flurpiridaz without further preparative HPLC purification. Results: Precursor 6 was obtained by multi-step synthesis starting from mucochloric acid (1) as a sole product with 35% yield and identified by spectroscopic measurement. Manually cold labeling experiments were performed using the stable isotope [19F]F, and TBA-HCO3 PTC provided desirable fluorinated compound with high yield. A fully automated [18F]Flurpiridaz synthesis on the ML-PT device provided 55–65% radiochemical yield with more than 98% radiochemical purity. The final product purification method demonstrated that [18F]Flurpiridaz could be obtained without an external preparative HPLC system as a pharmaceutical quality. Conclusion: A novel and fascinating strategy was developed for the fully automated synthesis of [18F]Flurpiridaz (7) on ML PT. Organic synthesis of precursor 6 was achieved with a desirable yield and characterized by NMR and HR-MS. A detailed set of cold experiments were completed for optimization conditions before hot trials and TBA-HCO3 increased molar activity with a minimum amount of side products. Radiolabeling showed that our self-designed automated synthesis method enables high radiochemical yield and radiochemical purity for the production of [18F]Flurpiridaz. The desirable radiopharmaceutical quality of the product was obtained without using an additional preparative HPLC system. [18F]Flurpiridaz (7) preserved its stability within 12 h and final specifications were consistent with the acceptance criteria in Ph. Eur. regulations. [ABSTRACT FROM AUTHOR]

Purpose: In this study, we aimed to investigate the utilization of 68Ga-FAPI PET/CT in comparison to 18FDG PET/CT to evaluate the peritoneal involvement of the gastrointestinal malignancies alongside primary lesions and other metastatic foci. Procedures: A total of 37 patients with various gastrointestinal malignancies with accompanying peritoneal involvement who underwent 68Ga-FAPI PET/CT and 18FDG PET/CT imaging between September 2020 and June 2021 were included in this retrospective study. SUVmax values of 68Ga-FAPI and 18FDG were compared according to lesion locations. Also, the lesion localization ability of both imaging was compared in patient basis. Results: Of the 37 patients with peritoneal involvement (23 males and 14 females; median age, 62.8 ± 12.7 years), 35.1% (n = 13) had colorectal cancer, 37.8% (n = 14) gastric cancer, and 27.0% (n = 10) pancreaticobiliary cancer. While 45.9% of them were operated, the remaining did not have surgery. The mean time interval between two studies was 3.2 days (range: 2–6 days). The mean SUVmax value of peritoneal metastases (p < 0.001) was significantly higher with 68Ga-FAPI PET/CT compared to that with 18FDG PET/CT, as in primary lesions (p < 0.001), lymph node metastases (p = 0.006), liver metastases (p = 0.002), and bone metastases (p = 0.018). A total of 185 lesions was detected in the initial assessment with 18FDG PET/CT. Of the total lesions detected with 18FDG PET/CT, 5 of them were evaluated as benign lesions with 68Ga-FAPI PET/CT also in accordance with the reference standard. In addition to 180 lesions detected with 18FDG PET/CT, a total of 37 additional malignant lesions, 12 of which were peritoneal metastases, were detected with 68Ga-FAPI PET/CT. Conclusion: 68Ga-FAPI PET/CT was determined to be superior to 18FDG PET/CT in terms of detection of peritoneal involvement with high image quality as well as primary tumor and other metastatic foci. Consequently, 68Ga-FAPI PET/CT can be used as a complementary imaging modality especially for inconclusive 18FDG findings due to the lack of accuracy of 18FDG PET/CT in some of the metastatic regions, especially in the liver. [ABSTRACT FROM AUTHOR]

Radiolabeled phosphonates have found widespread applications in nuclear medicine for the treatment of bone metastases. Even though considerable attention has been devoted to the administration of radiolabeled phosphonates to the patients, quality control (QC) studies belong to detection of them are still speculative and need to be improved. Herein, practical, efficient, and more reliable high‐performance liquid chromatograpy (HPLC) methods were described for the first time. Radiochemical purity was easily determined by our developed analytical methods. N,N‐Dimethylhexylamine and N,N‐dimethyltetradecylamine were furnished as suitable ion pair reagents for the identification of radiopharmaceutical products. Effects of column type, pH of the mobile phase, and salt concentration were also examined. [ABSTRACT FROM AUTHOR]

Objective: We aimed to evaluate the gallium-68-labeled fibroblast-activation protein inhibitor ( 68 Ga-FAPI) positron emission tomography/computed tomography (PET/CT) in localizing papillary thyroid carcinoma (PTC) foci in patients with biochemical relapse. Papillary thyroid carcinoma has achieved biochemical recovery after appropriate treatment and had biochemical relapse in the last follow-up were included in this retrospective study. Gallium-68-FAPI and fluorine-18-fluorodeoxyglucose ( 68 F-FDG) PET/CT were performed to detect recurrence foci., Subjects and Methods: Biochemically relapsed patients who underwent total thyroidectomy and were diagnosed with pathologically differentiated thyroid cancer were included in our study. Gallium-68-FAPI and 18 F-FDG PET/CT imaging methods were used to determine the focus of metastasis or recurrence in all patients., Results: Among 29 patients enrolled to the study, pathological subgroups were papillary (n=26) and poorly differentiated (n=3) PTC. Anti-thyroglobulin (TG) antibody positivity were noted in 5 of the patients, while all 29 of them were TG positive and had been consist of three groups as follows: 2-10ng/mL (n=4), 11-300ng/mL (n=14), 301ng/mL and above (n=11). Recurrence was detected in 72.4% (n=21) and 86% (n=25) of the patients via 18 F-FDG and 68 Ga-FAPI, respectively. Accuracy of detection noted as 100% (5/5), 75% (3/4), and 92.9% (13/14) in groups with the anti-TG antibody positivity, TG levels of 2-10ng/mL and 11-300ng/mL, respectively, when the two imaging modalities were utilized together. Furthermore, accuracy of 68 Ga-FAPI was 100% (11/11) in the group with TG levels of 301ng/mL and above, whereas accuracy of 18 F-FDG was 81.8% (9/11). Lastly, median maximum standardized uptake value (SUVmax) of recurrent lesions detected by the 68 Ga-FAPI (median SUVmax: 6.0) were statistically higher than the ones detected by the 18 F-FDG (median SUVmax: 3.7) (P=0.002)., Conclusion: In recurrent PTC especially in case of higher TG levels, 68 Ga-FAPI can be used in patients with inconclusive 18 F-FDG findings.

Background: The synthesis of 225 Actinium derivatives was afforded by using PSMA- 617, DOTATATE peptides, and EDTMP ligand. Detailed experiments, quality control (QC), and stability studies were also well described. The radiolabelling reactions were performed in mild conditions with desirable radiochemical yields and high radiochemical purities., Methods: PSMA-617, DOTATATE were radiolabelled with 225 Actinium in 0.1 M HCl in the presence of ascorbate buffer solution and passed through the C-18 light cartridge for purification and the product was eluted by ethanol-water solution. EDTMP was also radiolabelled with 225 Actinium without using any stabilizer and purification step. All products were well analyzed by R-TLC and R-HPLC. The stability of those compounds was also studied within the validity period of time., Results: 225 Ac-DOTATATE and 225Ac-PSMA-617 were obtained at the same condition. The radiochemical yield of 225Ac-DOTATATE was less than 225 Ac-PSMA 617. The stability experiments indicating decay daughters of 225 Actinium appeared after T0 +1 h due to the recoil effect radiolysis. On the other hand, 225 Ac-EDTMP was more stable than DOTA-peptide radiolabelled compounds. 225 Ac-EDTMP was produced with more than 95% radiochemical yield and 99% radiochemical purity., Conclusion: A detailed chemistry study was presented for the synthesis of 225 Actinium derivatives in mild conditions with absolute radiochemical purities and high yields. The experimental results showed that 225 Ac-EDTMP could be a suitable radiopharmaceutical alternative for bone metastases arising from primer tumors as a cocktail therapy., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)