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From 29th September to 2nd October 2025, European Radiation Protection Week was hosted in London by the UK Health Security Agency with Imperial College London's Department of Epidemiology and Biostatistics. The meeting brought together the platforms under the MEENAS umbrella (MELODI, EURADOS, EURAMED, NERIS, ALLIANCE, and SHARE) to deliver a diverse programme of presentations and posters spanning the breadth of radiation protection research. This paper provides a summary of the meeting.

Objectives: FDG PET/MRI is a promising imaging modality for nodal staging in rectal cancer; however, its role remains to be defined. We aimed to assess its performance in detecting mesorectal malignant lymph node involvement based on both metabolic and morphological criteria at PET/MRI versus at MRI alone.

Materials & methods: Sixty-five patients (median age 70 years, IQR 61–74; 39 men) were examined with FDG PET/MRI followed by individual anatomical matching of mesorectal nodal structures between histopathology and MRI. PET N-stage assessment was evaluated using FDG uptake over background levels, MRI N-stage by the 2016 European Society of Gastrointestinal and Abdominal Radiology (ESGAR) consensus criteria and PET/MRI was evaluated using both in combination. Histopathological assessment served as gold standard, and the accuracy of identifying malignancy at both nodal and patient level was calculated. Furthermore, FDG PET/MRI and MRI using ESGAR criteria for nodal restaging after neoadjuvant treatment were also evaluated.

Results: In total, 835 nodal structures were matched, of which 104 were malignant (12%); among these, 59/104 (57%) were histopathologically proven lymph node metastases. MRI alone yielded a sensitivity of 54% and specificity of 85% for nodal malignancy, while the corresponding estimates for FDG-avidity gave a 75% sensitivity and 79% specificity. The different combined FDG PET/MRI criteria for malignancy were evaluated: FDG-positivity or malignancy according to ESGAR criteria resulted in a sensitivity of 76%; while the combination of FDG-positivity and malignancy according to ESGAR criteria achieved a specificity of 90%.

Conclusion: Compared to MRI alone, FDG PET/MRI offers potential added value by reducing the risk of nodal understaging.

BACKGROUND: Metastasis-directed stereotactic body radiotherapy (MD-SBRT) has shown promise in retrospective and phase II studies for oligometastatic hormone-sensitive prostate cancer. However, prospective randomized phase III data-particularly in newly diagnosed cases and in combination with androgen deprivation therapy and next-generation androgen receptor pathway inhibitors-are limited. The METRO trial investigates the addition of MD-SBRT to standard of care in patients with prostate-specific membrane antigen (PSMA) PET/CT-detected oligometastatic disease.

METHODS: METRO is a multicentre, double arm, open-label, phase III randomized trial comparing MD-SBRT plus standard of care versus standard of care alone in patients with one to three PSMA PET/CT-detected distant metastases. The PSMA-RADS scale is used to support inclusion, and only patients with PSMA-RADS 4 or 5 lesions in bone or non-regional lymph nodes are eligible.

Standard of care includes time-limited androgen deprivation therapy and/or androgen receptor pathway inhibitor, as well as local radiotherapy to the prostate or prostate bed. Patients are stratified by disease type (synchronous or metachronous) and metastasis location (lymph node/bone). The primary endpoint is biochemical progression-free survival; secondary endpoints include time to castration-resistant prostate cancer, adverse events, and health-related quality of life.

The intervention is prescribed either 30 Gy in 3 fractions or 40 Gy in 5 fractions and delivered by stereotactic treatment principles.

DISCUSSION: The METRO trial investigates the added value of combining MD-SBRT with time-limited intensified hormonal therapy in both synchronous and metachronous oligometastatic hormone-sensitive prostate cancer staged by PSMA‑PET/CT. The use of the PSMA-RADS scale for inclusion ensures a standardized and reproducible approach for patient selection.

TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04983095.

According to glymphatic system theory, cerebrospinal fluid (CSF) perfuses the brain’s interstitial space to support waste clearance, but the magnitude of this flow and the outflow pathway of interstitial fluid (ISF) in humans remain uncertain. To achieve flow quantification, we applied a compartment-model approach applied in conjunction with serial quantitative MRI data acquired after intrathecal gadolinium administration. Using the method, we estimated CSF-to-ISF inflow to 45 ± 20 mL/h, in patients with suspected idiopathic normal pressure hydrocephalus. Tissue-specific contributions were 34 ± 14 mL/h in cortical gray matter, 11±6 mL/h in white matter, and 0.4 ± 0.3 mL/h in subcortical gray matter, suggesting that CSF perfusion occurs primarily in superficial regions near the subarachnoid space. A lack of correlation between inflow and total craniospinal system outflow (r = 0.03, P = 0.91) suggested that ISF recirculates back into CSF rather than exiting the craniospinal system via a separate route. Independent experiments in healthy older individuals using intravenous gadolinium administration supported ISF-to-CSF recirculation, where contrast material that presumably crossed the blood–brain barrier subsequently appeared in the subarachnoid space, allowing ISF-to-CSF flow quantification. These findings provide a quantitative framework for studying brain clearance in humans and support subarachnoid space recirculation as an important efflux route.

Aging-related dopamine decline has been suggested as a key factor behind individual differences in cognitive decline at older ages. Thus far, the hypothesized age-dopamine-cognition triad has been extrapolated from cross-sectional studies, which cannot uncover change associations. Using data from the longitudinal Cognition, Brain, and Aging (COBRA) study, we examined whether dopamine D2-receptor availability changes are correlated with cognitive changes across individuals in old age. At the first wave, 181 healthy adults aged 64 to 68 years underwent positron emission tomography with 11C-raclopride, magnetic resonance imaging, multiple cognitive tests assessing episodic memory, working memory, and perceptual speed, and mapping of health-related factors. The returnees (n = 129 after 5 years; n = 93 after 10 years) were representative of the parent sample regarding gender composition, educational attainment, cognitive performance, and dopamine D2-receptor status at baseline. Bayesian structural equation modeling revealed mean decline and individual differences in decline for striatal dopamine D2-receptor availability (approximately-5% per decade) and for all three cognitive abilities. Changes in dopamine D2-receptor and a factor of general cognition were positively correlated (r = 0.31, P(r > 0.00) > 0.95). Taken together, these longitudinal findings support that striatal dopamine decline is associated with cognitive aging, possibly reflecting dopamine influences via striato-Thalamo-cortical loops on general cognitive functions.

Technological innovations in genomics and related fields have facilitated large sequencing efforts, supported new biological discoveries in cancer, and spawned an era of liquid biopsy biomarkers. Despite these advances, precision oncology has practical constraints, partly related to cancer's biological diversity and spatial and temporal complexity. Advanced imaging technologies are being developed to address some of the current limitations in early detection, treatment selection and planning, drug delivery, and therapeutic response, as well as difficulties posed by drug resistance, drug toxicity, disease monitoring, and metastatic evolution. We discuss key areas of advanced imaging for improving cancer outcomes and survival. Finally, we discuss practical challenges to the broader adoption of precision imaging in the clinic and the need for a robust translational infrastructure.

Although age differences in the dopamine system have been suggested to contribute to age-related cognitive decline based on cross-sectional data, recent large-scale cross-sectional studies reported only weak evidence for a correlation among aging, dopamine receptor availability, and cognition. Regardless, longitudinal data remain essential to make robust statements about dopamine losses as a basis for cognitive aging. We present correlations between changes in D2/3 dopamine receptor availability and changes in working memory measured over 5 yr in healthy, older adults (n = 128, ages 64 to 68 yr at baseline). Greater decline in D2/3 dopamine receptor availability in working memory-relevant regions (caudate, middle frontal cortex, hippocampus) was related to greater decline in working memory performance in individuals who exhibited working memory reductions across time (n = 43; caudate: rs = 0.494; middle frontal cortex: rs = 0.506; hippocampus; rs = 0.423), but not in individuals who maintained performance (n = 41; caudate: rs = 0.052; middle frontal cortex: rs = 0.198; hippocampus; rs = 0.076). The dopamine–working memory link in decliners was not observed in the orbitofrontal cortex, which does not belong to the core working memory network. Our longitudinal analyses support the notion that aging-related changes in the dopamine system contribute to working memory decline in aging.

Background: Normal brain aging is associated with dopamine decline, which has been linked to age-related cognitive decline. Factors underlying individual differences in dopamine integrity at older ages remain, however, unclear. Here we aimed at investigating: (i) whether inflammation is associated with levels and 5-year changes of in vivo dopamine D2-receptor (DRD2) availability, (ii) if DRD2-inflammation associations differ between men and women, and (iii) whether inflammation and cerebral small-vessel disease (white-matter lesions) serve as two independent predictors of DRD2 availability.

Methods: Analyses were performed in a sample of healthy adults > 60 years assessed at two measurement occasions separated by 5 years. At both occasions, DRD2 availability was estimated by ¹¹C-raclopride PET, and white-matter lesions by MRI. Inflammation was assessed by two C-reactive protein-associated DNA methylation scores at study baseline.

Results: Individuals with higher DNA methylation scores at baseline showed reduced striatal DRD2 availability. An interaction was found between DNA methylation scores and sex in relation to striatal DRD2 availability, such that associations were found in men but not in women. DNA methylation scores at study entrance were not significantly associated with 5-year striatal DRD2 decline rates. No significant association was found between DNA methylation scores and white-matter lesions, but higher scores as well as higher lesion burden were independently associated with reduced striatal DRD2 availability in men.

Conclusions: These findings suggest negative associations between one proxy of inflammation and DRD2 availability in older adults, selectively for men who had higher DNA methylation scores. Future studies should investigate other inflammatory markers in relation to dopamine integrity.

Normal aging is associated with decline in dopamine function. Factors associated with individual differences in dopamine decline rates remain unclear but are important to map to spare dopamine-related functions, such as cognition. Here we focused on manifestations of cerebral small-vessel disease from magnetic resonance imaging (white-matter lesions, lacunes, and perivascular space dilation) and vascular risk factors (e.g., hypertension, body mass index (BMI), and hyperlipidemia). We assessed striatal dopamine D2-like receptor (DRD2) reductions across five years in healthy, older adults (n = 129, ages: 64–68 years at baseline) using 11C-raclopride/positron emission tomography. Manifestations of confluent lesions and lacunes at baseline had additive effects on DRD2 decline. Individuals with both manifestations showed fastest DRD2 decline rates (∼ −4 %), followed by those with one manifestation (∼ −2 %), whereas individuals spared of confluent lesions and lacunes showed stable DRD2 levels over time (∼ 0 % change). Furthermore, individuals with confluent lesions or lacunes showed more marked decline in perceptual speed performance, as compared to individuals spared of these manifestations (p < 0.05). Higher systolic blood pressure and lower BMI at baseline were associated with faster 5-year DRD2 decline in the putamen (r = -0.17, p < 0.05) and caudate (r = 0.23, p < 0.05), respectively. Together, confluent lesions and lacunes explained up to 8 % of striatal DRD2 change, and up to 10 % when adding hypertension and BMI to the model. These findings suggest that hallmarks of SVD and certain vascular risk factors predispose faster DRD2 decline in aging and may thus serve as factors to consider in future interventions.

Background: Glioblastoma is the most aggressive and malignant brain tumor, characterized by a high degree of heterogeneity, invasiveness, and resistance to treatment. Patients with glioblastoma have a very poor prognosis despite multimodal interventions. In this study, we investigated how 18F-fluorothymidine (18F-FLT) PET combined with contrast-enhanced MRI and blood metabolomics can contribute to evaluate prognosis and treatment response for patients with glioblastoma.

Methods: Patients, scheduled for surgery due to suspected high-grade glioma were included in this clinical study and underwent four 18F-FLT-PET/MRI examinations prior to surgery and during standard treatment. Blood samples were collected and analyzed by metabolomics. Patients were grouped according to survival as long-time survivors (>3 years) and short-time survivors (<500 days).

Results: Both 2 and 6 weeks into treatment, short-time survivors displayed a significantly larger tumor volume than long-time survivors. When comparing MRI findings during treatment, long-time survivors displayed a substantial tumor decrease, whereas the short-time survivors showed minor or no effect. Regarding 18F-FLT-PET the results were not as unambiguous. Furthermore, there was a clear and significant separation in the metabolomic pattern in blood between the survival groups and across treatment time points.

Conclusions: MRI measures of tumor volume and growth during treatment appear to be prognostic clinical factors that affect outcome. Metabolomic patterns in blood differ significantly between the defined survival groups and may serve as support for an early forecast of prognosis. We also observe a clear separation in metabolite levels between different time points during treatment, which likely reflects treatment effects.