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Purpose To provide practice guideline/procedure standards for diagnostics and therapy (theranostics) of meningiomas using radiolabeled somatostatin receptor (SSTR) ligands. Methods This joint practice guideline/procedure standard was collaboratively developed by the European Association of Nuclear Medicine (EANM), the Society of Nuclear Medicine and Molecular Imaging (SNMMI), the European Association of Neurooncology (EANO), and the PET task force of the Response Assessment in Neurooncology Working Group (PET/RANO). Results Positron emission tomography (PET) using somatostatin receptor (SSTR) ligands can detect meningioma tissue with high sensitivity and specificity and may provide clinically relevant information beyond that obtained from structural magnetic resonance imaging (MRI) or computed tomography (CT) imaging alone. SSTR-directed PET imaging can be particularly useful for differential diagnosis, delineation of meningioma extent, detection of osseous involvement, and the differentiation between posttherapeutic scar tissue and tumour recurrence. Moreover, SSTR-peptide receptor radionuclide therapy (PRRT) is an emerging investigational treatment approach for meningioma. Conclusion These practice guidelines will define procedure standards for the application of PET imaging in patients with meningiomas and related SSTR-targeted PRRTs in routine practice and clinical trials and will help to harmonize data acquisition and interpretation across centers, facilitate comparability of studies, and to collect larger databases. The current document provides additional information to the evidence-based recommendations from the PET/RANO Working Group regarding the utilization of PET imaging in meningiomas Galldiks (Neuro Oncol. 2017 ;19(12):1576–87). The information provided should be considered in the context of local conditions and regulations.

Oligometastatic disease represents a clinical and anatomical manifestation between localised and polymetastatic disease. In prostate cancer, as with other cancers, recognition of oligometastatic disease enables focal, metastasis-directed therapies. These therapies potentially shorten or postpone the use of systemic treatment and can delay further metastatic progression, thus increasing overall survival. Metastasis-directed therapies require imaging methods that definitively recognise oligometastatic disease to validate their efficacy and reliably monitor response, particularly so that morbidity associated with inappropriately treating disease subsequently recognised as polymetastatic can be avoided. In this Review, we assess imaging methods used to identify metastatic prostate cancer at first diagnosis, at biochemical recurrence, or at the castration-resistant stage. Standard imaging methods recommended by guidelines have insufficient diagnostic accuracy for reliably diagnosing oligometastatic disease. Modern imaging methods that use PET-CT with tumour-specific radiotracers (choline or prostate-specific membrane antigen ligand), and increasingly whole-body MRI with diffusion-weighted imaging, allow earlier and more precise identification of metastases. The European Organisation for Research and Treatment of Cancer (EORTC) Imaging Group suggests clinical algorithms to integrate modern imaging methods into the care pathway at the various stages of prostate cancer to identify oligometastatic disease. The EORTC proposes clinical trials that use modern imaging methods to evaluate the benefits of metastasis-directed therapies.

In contrast to external high energy photon or proton therapy, targeted radionuclide therapy (TRNT) is a systemic cancer treatment allowing targeted irradiation of a primary tumor and all its metastases, resulting in less collateral damage to normal tissues. The α-emitting radionuclide bismuth-213 (213Bi) has interesting properties and can be considered as a magic bullet for TRNT. The benefits and drawbacks of targeted alpha therapy with 213Bi are discussed in this review, covering the entire chain from radionuclide production to bedside. First, the radionuclide properties and production of 225Ac and its daughter 213Bi are discussed, followed by the fundamental chemical properties of bismuth. Next, an overview of available acyclic and macrocyclic bifunctional chelators for bismuth and general considerations for designing a 213Bi-radiopharmaceutical are provided. Finally, we provide an overview of preclinical and clinical studies involving 213Bi-radiopharmaceuticals, as well as the future perspectives of this promising cancer treatment option.

Terbium features four clinically interesting radionuclides for application in nuclear medicine: terbium-149, terbium-152, terbium-155, and terbium-161. Their identical chemical properties enable the synthesis of radiopharmaceuticals with the same pharmacokinetic character, while their distinctive decay characteristics make them valuable for both imaging and therapeutic applications. In particular, terbium-152 and terbium-155 are useful candidates for positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging, respectively; whereas terbium-149 and terbium-161 find application in α- and β -/Auger electron therapy, respectively. This unique characteristic makes the terbium family ideal for the \"matched-pair\" principle of theranostics. In this review, the advantages and challenges of terbium-based radiopharmaceuticals are discussed, covering the entire chain from radionuclide production to bedside administration. It elaborates on the fundamental properties of terbium, the production routes of the four interesting radionuclides and gives an overview of the available bifunctional chelators. Finally, we discuss the preclinical and clinical studies as well as the prospects of this promising development in nuclear medicine.

PurposeA multidisciplinary expert panel convened to formulate state-of-the-art recommendations for optimisation of selective internal radiation therapy (SIRT) with yttrium-90 (90Y)-resin microspheres.MethodsA steering committee of 23 international experts representing all participating specialties formulated recommendations for SIRT with 90Y-resin microspheres activity prescription and post-treatment dosimetry, based on literature searches and the responses to a 61-question survey that was completed by 43 leading experts (including the steering committee members). The survey was validated by the steering committee and completed anonymously. In a face-to-face meeting, the results of the survey were presented and discussed. Recommendations were derived and level of agreement defined (strong agreement ≥ 80%, moderate agreement 50%–79%, no agreement ≤ 49%).ResultsForty-seven recommendations were established, including guidance such as a multidisciplinary team should define treatment strategy and therapeutic intent (strong agreement); 3D imaging with CT and an angiography with cone-beam-CT, if available, and 99mTc-MAA SPECT/CT are recommended for extrahepatic/intrahepatic deposition assessment, treatment field definition and calculation of the 90Y-resin microspheres activity needed (moderate/strong agreement). A personalised approach, using dosimetry (partition model and/or voxel-based) is recommended for activity prescription, when either whole liver or selective, non-ablative or ablative SIRT is planned (strong agreement). A mean absorbed dose to non-tumoural liver of 40 Gy or less is considered safe (strong agreement). A minimum mean target-absorbed dose to tumour of 100–120 Gy is recommended for hepatocellular carcinoma, liver metastatic colorectal cancer and cholangiocarcinoma (moderate/strong agreement). Post-SIRT imaging for treatment verification with 90Y-PET/CT is recommended (strong agreement). Post-SIRT dosimetry is also recommended (strong agreement).ConclusionPractitioners are encouraged to work towards adoption of these recommendations.

We provide updated guidance and standards for the indication, acquisition, and interpretation of [ 18 F]FDG PET/CT for plasma cell disorders. Procedures and characteristics are reported and different scenarios for the clinical use of [ 18 F]FDG PET/CT are discussed. This document provides clinicians and technicians with the best available evidence to support the implementation of [ 18 F]FDG PET/CT imaging in routine practice and future research.

Background [ 68 Ga]PentixaFor detects C-X-C chemokine receptor type 4 (CXCR4) overexpression in various malignancies, such as multiple myeloma and non-Hodgkin lymphomas, as well as in endocrine and inflammatory disorders. This study aimed to develop an Al 18 F-labeled radiotracer derived from LY2510924 for CXCR4-targeted imaging, leveraging the physical and logistical advantages of fluorine-18. Methods We designed a CXCR4-specific radioprobe, [ 18 F]AlF-NOTA-SC, based on LY2510924 by incorporating a triglutamate linker and NOTA chelator to enable Al 18 F-labeling. The in vitro CXCR4 affinity was assessed using cell-based binding assays. Subsequently, in vivo pharmacokinetics and tumor uptake of [ 18 F]AlF-NOTA-SC were assessed in naïve mice and mice with xenografts derived from U87.CD4/U87.CD4.CXCR4 and MM.1 S cells. Finally, biodistribution was determined in a non-human primate using PET-MR. Results Compared to Ga-PentixaFor, AlF-NOTA-SC demonstrated similar in vitro affinity for human CXCR4. [ 18 F]AlF-NOTA-SC was produced with a decay-corrected radiochemical yield of 21.0 ± 7.1% and an apparent molar activity of 16.4 ± 3.6 GBq/µmol. In [ 18 F]AlF-NOTA-SC binding assays on U87.CD4.CXCR4 cells, the total bound fraction was 7.1 ± 0.5% (58% blocking by AMD3100). In naïve mice, the radiotracer did not accumulate in any organs; however, it showed a significant CXCR4-specific uptake in xenografted tumors (SUVmean U87.CD4  = 0.04 ± 0.00 (n = 3); SUVmean U87.CD4.CXCR4  = 3.04 ± 0.65 (n = 3); SUVmean MM.1 S  = 1.95 ± 0.11 (n = 3)). In a non-human primate, [ 18 F]AlF-NOTA-SC accumulated in CXCR4 expressing organs, such as the spleen and bone marrow. Conclusion [ 18 F]AlF-NOTA-SC exhibited CXCR4-specific uptake in vitro and in vivo, with fast and persistent tumor accumulation, making it a strong candidate for clinical translation as an 18 F-alternative to [ 68 Ga]PentixaFor. Graphical abstract

PurposeThe widespread use of gallium-68-labelled somatostatin analogue (SSA) PET, the current standard for somatostatin receptor (SSTR) imaging, is limited by practical and economic challenges that could be overcome by a fluorine-18-labelled alternative, such as the recently introduced [18F]AlF-NOTA-octreotide ([18F]AlF-OC). This prospective trial aimed to evaluate safety, dosimetry, biodistribution, pharmacokinetics and lesion targeting of [18F]AlF-OC and perform the first comparison with [68Ga]Ga-DOTATATE in neuroendocrine tumour (NET) patients.MethodsSix healthy volunteers and six NET patients with a previous clinical [68Ga]Ga-DOTATATE PET were injected with an IV bolus of 4 MBq/kg [18F]AlF-OC. Healthy volunteers underwent serial whole-body PET scans from time of tracer injection up to 90 min post-injection, with an additional PET/CT at 150 and 300 min post-injection. In patients, a 45-min dynamic PET was acquired and three whole-body PET scans at 60, 90 and 180 min post-injection. Absorbed organ doses and effective doses were calculated using OLINDA/EXM. Normal organ uptake (SUVmean) and tumour lesion uptake (SUVmax and tumour-to-background ratio (TBR)) were measured. A lesion-by-lesion analysis was performed and the detection ratio (DR), defined as the fraction of detected lesions was determined for each tracer.Results[18F]AlF-OC administration was safe and well tolerated. The highest dose was received by the spleen (0.159 ± 0.062 mGy/MBq), followed by the urinary bladder wall (0.135 ± 0.046 mGy/mBq) and the kidneys (0.070 ± 0.018 mGy/MBq), in accordance with the expected SSTR-specific uptake in the spleen and renal excretion of the tracer. The effective dose was 22.4 ± 4.4 μSv/MBq. The physiologic uptake pattern of [18F]AlF-OC was comparable to [68Ga]Ga-DOTATATE. Mean tumour SUVmax was lower for [18F]AlF-OC (12.3 ± 6.5 at 2 h post-injection vs. 18.3 ± 9.5; p = 0.03). However, no significant differences were found in TBR (9.8 ± 6.7 at 2 h post-injection vs. 13.6 ± 11.8; p = 0.35). DR was high and comparable for both tracers (86.0% for [68Ga]Ga-DOTATATE vs. 90.1% for [18F]AlF-OC at 2 h post-injection; p = 0.68).Conclusion[18F]AlF-OC shows favourable kinetic and imaging characteristics in patients that warrant further head-to-head comparison to validate [18F]AlF-OC as a fluorine-18-labelled alternative for gallium-68-labelled SSA clinical PET.Trial registrationClinicaltrials.gov: NCT03883776, EudraCT: 2018-002827-40

Background: α-emitting Peptide Receptor Radionuclide Therapy (α-PRRT) is emerging as a promising new generation of PRRT for neuroendocrine tumors (NETs), providing enhanced tumor cell cytotoxicity and reduced irradiation of adjacent healthy tissues due to its high linear energy transfer (LET) and short particle range. This review summarizes available clinical evidence on α-PRRT using different α-emitting isotopes, including actinium-225, lead-212, and bismuth-213, in somatostatin receptor (SSTR)-positive NETs. Methods: A comprehensive literature search was conducted across PubMed, Embase, Cochrane Library, Scopus, Web of Science, and ClinicalTrials.gov, as well as major oncology congress abstracts (ENETS, ESMO, ASCO). Eligible studies included clinical trials evaluating α-PRRT in patients with advanced SSTR-positive NETs, reporting therapeutic response and adverse events. The primary endpoint was the objective response rate (ORR); secondary endpoints included disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and safety. Results: Seven studies encompassing 150 patients were included. Treatment with [225Ac]Ac-DOTATATE yielded a pooled ORR of 50% and a DCR of 81.3% across 121 evaluable patients. The best responses were observed in patients who had previously responded to β-PRRT (ORR 70.4%, DCR 96.3%), while one-third of β-PRRT–refractory patients achieved partial or complete responses. [212Pb]Pb-DOTAMTATE demonstrated an ORR of 56.8% and DCR of 100% in preliminary phase II results, though dysphagia was noted in 34% of patients. [213Bi]Bi-DOTATOC and [212Pb]Pb-VMT-α-NET studies also showed promising disease control with minimal grade ≥ 3 hematologic or renal toxicities. Across all studies, α-PRRT was well tolerated, with predominantly low-grade hematologic adverse events and no significant hepatic or renal toxicity. Conclusions: Clinical data to date indicate that α-PRRT offers meaningful therapeutic benefit in patients with metastatic or treatment-refractory NETs, achieving favorable response rates with manageable toxicity. Early results support α-PRRT as a potential first- or second-line therapeutic option. Ongoing phase III trials will be critical to confirm its long-term safety, survival outcomes, and role in routine clinical practice.