Driving the Future of Nuclear Medicine

Radiopharmaceuticals in Nasopharyngeal Cancer

Nasopharyngeal carcinoma (NPC) is a prevalent malignant epithelial tumor and epidemic in East and Southeast Asia. The pathology of NPC was characterized by local infiltration early, regional nodal involvement and distant metastases. The specialty of pathological sites makes it hard to early diagnosis, which relies on multiple imaging techniques (MRI, CT scans, and endoscopy) and biopsy. Precise staging of NPC and targeted therapies are vital to the therapeutic efficacy and prognosis. Noninvasive and high-resolution imaging techniques are urgently needed for NPC. Radiopharmaceuticals and imaging equipment (single-photon emission computed tomography (SPECT) and positron emission tomography (PET)) are rapidly developed and applied in the diagnosis of NPC. In this review, we summarized the radiopharmaceuticals in NPC. Reviewing the radiopharmaceuticals in NPC would greatly help further optimize the radioligands and discover novel targets.

Analyzing Radiation Protection Risks in Nuclear Medicine: Cause Investigation and WSR-Based Countermeasure Evaluation

Objective

To analyze and investigate the causes of radiation protection safety risks in nuclear medicine diagnosis and treatment, formulate radiation protection safety management countermeasures, and evaluate their effectiveness.

Methods

In October 2020, the Department of Nuclear Medicine at our hospital established a radiation protection safety management team, utilizing association rules to investigate and analyze the causes of radiation protection safety risks. A Wuli-Shili-Renli (WSR) system management approach was implemented, addressing physical (Wuli), procedural (Shili), and human factors (Renli) to improve technical safeguards, optimize processes, and enhance personnel awareness. A total of 1200 patients receiving diagnosis and treatment were divided into two groups. The control group (600 cases) used standard inspection-based radiation protection, while the observation group (600 cases) adopted WSR system management in addition to standard measures. Radiation protection risk control effectiveness and safety control capability scores were compared between the two groups.

Results

The proportions of excessive diagnostic doses and additional radiation harm in the observation group were both lower than those in the control group (P < 0.05); the proportions of risk sources, including building environment, protective measures, dose monitoring, safety awareness, and waste disposal, in the observation group were all lower than those in the control group (P < 0.05). The observation group's scores in radiation protection theory, practical risk management skills, and radiation protection safety literacy, as well as the total score, were higher than those of the control group (P < 0.05).

Conclusion

The WSR system management approach effectively reduces radiation protection safety risks, improves the diagnostic and therapeutic environment, minimizes radiation exposure to patients and staff, and enhances safety risk management levels in nuclear medicine departments.

Synthesis and Preclinical Evaluation of Fluorinated 5-Azaindoles as CB2 PET Radioligands

Several classes of cannabinoid receptor type 2 radioligands have been evaluated for imaging of neuroinflammation, with successful clinical translation yet to take place. Here we describe the synthesis of fluorinated 5-azaindoles and pharmacological characterization and in vivo evaluation of 18F-radiolabeled analogues. [18F]2 (hCB2 Ki = 96.5 nM) and [18F]9 (hCB2 Ki = 7.7 nM) were prepared using Cu-mediated 18F-fluorination with non-decay-corrected radiochemical yields of 15 ± 6% and 18 ± 2% over 85 and 80 min, respectively, with high radiochemical purities (>97%) and molar activities (140-416 GBq/μmol). In PET imaging studies in rats, both [18F]2 and [18F]9 demonstrated specific binding in CB2-rich spleen after pretreatment with CB2-specific GW405833. Moreover, [18F]9 exhibited higher brain uptake at later time points in a murine model of neuroinflammation compared with a healthy control group. The results suggest further evaluation of azaindole based CB2 radioligands is warranted in other neuroinflammation models.

State of the art of radiomic analysis in the clinical management of prostate cancer: A systematic review

We present the current clinical applications of radiomics in the context of prostate cancer (PCa) management. Several online databases for original articles using a combination of the following keywords: "(radiomic or radiomics) AND (prostate cancer or prostate tumour or prostate tumor or prostate neoplasia)" have been searched. The selected papers have been pooled as focus on (i) PCa detection, (ii) assessing the clinical significance of PCa, (iii) biochemical recurrence prediction, (iv) radiation-therapy outcome prediction and treatment efficacy monitoring, (v) metastases detection, (vi) metastases prediction, (vii) prediction of extra-prostatic extension. Seventy-six studies were included for qualitative analyses. Classifiers powered with radiomic features were able to discriminate between healthy tissue and PCa and between low- and high-risk PCa. However, before radiomics can be proposed for clinical use its methods have to be standardized, and these first encouraging results need to be robustly replicated in large and independent cohorts.

Synthesis and Pharmacological Evaluation of Fluorinated Quinoxaline-Based κ-Opioid Receptor (KOR) Agonists Designed for PET Studies

κ-Opioid receptors (KORs) play a predominant role in pain alleviation, itching skin diseases, depression and neurodegenerative disorders such as multiple sclerosis. Therefore, imaging of KOR by a fluorinated PET tracer was envisaged. Two strategies were followed to introduce a F atom into the very potent class of cis,trans-configured perhydroquinoxalines. Whereas the synthesis of fluoroethyltriazole 2 has already been reported, fluoropyrrolidines 14 (1-[2-(3,4-dichlorophenyl)acetyl]-8-[(R)-3-fluoropyrrolidin-1-yl]-perhydroquinoxalines) were prepared by SN2 substitution of a cyclic sulfuric acid derivative with hydroxypyrrolidine and subsequent transformation of the OH moiety into a F substituent. Fluoropyrrolidines 14 showed similar low-nanomolar KOR affinity and selectivity to the corresponding pyrrolidines, but the corresponding alcohols were slightly less active. In the cAMP and β-arrestin assay, 14b (proton at the 4-position) exhibited similar KOR agonistic activity as U-50,488. The fluoro derivatives 14b and 14c (CO2CH3 at the 4-position) revealed KOR-mediated anti-inflammatory activity as CD11c and the IFN-γ production were reduced significantly in mouse and human dendritic cells. Compounds 14b and 14-c also displayed anti-inflammatory and immunomodulatory activity in mouse and human T cells. The PET tracer [18F]-2 was prepared by 1,3-dipolar cycloaddition. In vivo, [18F]-2 did not label KOR due to very fast elimination kinetics. Nucleophilic substitution of a mesylate precursor provided [18F]-14c. Unfortunately, defluorination of [18F]-14c occurred in vivo, which was analyzed in detail by in vitro studies.