To evaluate the robustness of the Hopkins criteria score (HCS) with regards to new PET reconstruction methods in therapy response assessment of head and neck cancer after (chemo)radiotherapy [(C)RT]. Maximum standardized uptake value and HCS were retrospectively assessed on fluorine-18-deoxyglucose PET/computed tomography (CT) 12 weeks after (C)RT for neck lymph nodes and the primary tumor site in 66 patients with three different reconstruction methods: standard high sensitivity reconstruction, European Association of Nuclear Medicine (EANM) Research Ltd. (EARL) reference standards 1 (EARL1) and 2 (EARL2). Histopathology (27 patients, 41%) or follow-up PET/CT 9 months after end of treatment (39 patients, 59%) served as reference standard. HCS 4 and 5 were rated as positive, 1-3 negative. The performance of HCS for all methods and intermethod concordance was assessed. A total of 17 (26%) patients had tumor persistence. There was no significant difference in the performance of the reconstruction methods regarding tumor persistence. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for PET/CT with HCS for overall tumor persistence was 77, 80, 57, 91, and 79% for sensitivity reconstruction, 65, 90, 69, 88, and 83% for EARL1 and 71, 82, 57, 89, and 79% for EARL2. The intermethod concordance of HCS across all sites demonstrated a substantial to perfect agreement with Cohens κ ranging from 0.6 to 1.0. PET/CT HCS for therapy response assessment in head and neck cancer serves as a robust Score independent of newer sensitive reconstructions. Despite the high NPV of PET/CT in this situation the unsatisfactory PPV remains challenging.

We revisited our early multiparametric dynamic choline PET data to demonstrate methodological feasibility for kinetic modelling and to highlight lessons relevant for current prostate-specific membrane antigen (PSMA) PET protocols. Nine men (aged 48-81 years) with biochemical recurrence of prostate cancer (prostate-specific antigen [PSA] range: 0.12-45.1 μg/L) underwent dynamic 18F-FECH PET/computed tomography. Patlak analysis produced two outcome values, influx rate (Ki) and volume of distribution. For quantitative analysis region of interests (ROIs) were drawn on a metabolically active focus of the prostate. For semiquantitative analysis the tracer accumulation in the ROIs was measured using the standardised uptake value. Arterial input functions were derived visually, and Patlak graphical analysis was performed. Correlations were explored between kinetic parameters, Gleason grade, and serum PSA. Spearman's correlation coefficients were calculated to assess the possible association between 18F choline uptake, clinical and histopathological characteristics. Dynamic acquisitions were technically feasible and analyzable before urinary excretion obscured the prostate. Time-activity curves plateaued after 1-2 min, and Patlak plots showed bilinear behaviour with measurable Ki and volume of distribution. Cancerous prostate tissue demonstrated increased perfusion compared with background tissue. No significant correlation was observed between kinetic parameters and PSA or Gleason grade. Dynamic 18F-choline PET provided quantitative kinetic parameters reflective of tumour perfusion. Although choline imaging has been largely superseded by PSMA PET because of superior tumour-to-background contrast and specificity, the technical principles established in this study remain directly applicable to current PSMA kinetic and parametric imaging.

Graves' disease is an autoimmune thyroid disorder mediated by thyroid-stimulating hormone receptor antibodies (TRAb). Vitamin D has been proposed as a modulator of autoimmunity; however, its relationship with thyroid hormone profiles in Graves' disease remains unclear. We retrospectively analyzed 182 patients with Graves' disease and 172 healthy controls. Serum 25-hydroxyvitamin D [25(OH)D] levels were stratified into four categories (<10, 10-20, 20-30, and ≥30 ng/ml). Thyroid parameters [thyroid-stimulating hormone (TSH), free T3 (fT3), free T4 (fT4)] were compared across groups using Kruskal-Wallis and Mann-Whitney U tests. Multivariate linear regression analyses were performed in the Graves' disease group to evaluate independent associations between 25(OH)D levels and thyroid hormone parameters, adjusting for age and sex. Severe vitamin D deficiency (<10 ng/ml) was associated with lower TSH levels compared with the other vitamin D groups (all P < 0.05). FT3 levels were highest in Group I and significantly lower in Groups II-IV (all P < 0.001). Similarly, fT4 levels were higher in Group I compared with Groups II and III ( P < 0.001) and Group IV ( P = 0.002). No statistically significant differences were observed among higher vitamin D categories. In multivariate analysis, serum 25(OH)D levels were independently and inversely associated with both fT3 ( β = -0.260, P < 0.001) and fT4 levels ( β = -0.253, P = 0.001), whereas no independent association was observed with TSH ( β = 0.107, P = 0.158). Serum 25(OH)D levels were inversely associated with peripheral thyroid hormone levels in patients with Graves' disease, while no independent association was observed with TSH. These findings suggest a potential relationship between vitamin D status and thyroid hormone dynamics; however, given the cross-sectional design, no causal inference can be made. Further prospective studies are required to clarify the clinical significance of this association.

Intracranial calcifications are commonly found in adults and may represent either benign or pathological lesions. Conventional imaging modalities detect static macrocalcifications but do not capture molecular microcalcification. In this study, we used 18 F-sodium fluoride (NaF) PET/computed tomography (CT) to idetect intracranial molecular microcalcification. A total of 127 subjects underwent 18 F-NaF PET/CT 90 min following radiotracer injection. Artificial intelligence-based quantification was performed to obtain regions of interest for the brainstem, basal ganglia (caudate and lentiform nuclei), insula, thalamus, and ventricles. Linear regression models were used to correlate NaF mean standardized uptake value (SUV mean ) with various clinical factors. NaF SUV mean was highest in the insula (0.8 ± 0.4) and brainstem (0.8 ± 0.3), while uptake was lowest in the caudate nucleus (0.1 ± 0.1). No differences were found in NaF SUV mean between healthy volunteers and at-risk patients. On multivariate regression, NaF SUV mean directly correlated with age in the brainstem ( β = 0.01, P = 0.01), lentiform nucleus ( β < 0.01, P = 0.02), and ventricles ( β < 0.01, P < 0.01). Male sex inversely correlated with NaF SUV mean in the insula ( β = -0.30, P < 0.01). There was an association between NaF SUV mean and BMI in the brainstem, caudate nucleus, lentiform nucleus, thalamus, and ventricles ( β ≤ 0.01, P < 0.01 in all regions). Thalamic and ventricular NaF SUV mean directly correlated with hypertension on univariate but not multivariate analysis. NaF PET/CT detects intracranial molecular microcalcification that is not visible on conventional CT and may provide insight into pathology associated with this biological process.

To provide an estimate of the uncertainties associated with the measurement of the glomerular filtration rate using the three-sample method. Retrospective data from 2063 patients whose glomerular filtration rate (GFR) was evaluated with Tc-99m diethylenetriaminepentaacetic acid using a three-sample method were compiled for this analysis. Input quantities to the GFR measurement were modelled as probability density functions (PDFs), and a Monte-Carlo method of propagating these PDFs was used to assess overall uncertainty in the measured GFR for each patient. The average uncertainty in the three-sample slope-intercept GFR was found to be 1.53% (with a coverage factor of k = 1). The dominant source of uncertainty in the slope-intercept GFR was the injected activity measurement using the radionuclide calibrator, except for slope-intercept GFRs below 20 ml/min whose dominant source of uncertainty was counting statistics. The Brøchner-Mortensen correction for the unmeasured initial plasma clearance phase became the dominant source of uncertainty in absolute GFR values above 20 ml/min, increasing the average uncertainty to 3.32% ( k = 1). The uncertainty in the absolute GFR was found to increase with increasing absolute GFR, because the Brøchner-Mortensen correction was associated with higher uncertainties for high GFRs. We have developed a framework to assess the measurement uncertainty in three-sample GFR studies for individual patients. While the uncertainty in the slope-intercept GFR is low, empirical corrections applied to derive the absolute GFR increase the uncertainty. Inclusion of measurement uncertainties in clinical GFR reports may aid clinical decision making, particularly in borderline cases.

With increasing use of [177Lu]-DOTATATE peptide receptor radionuclide therapy (PRRT) across the UK, variation in clinical and practical delivery aspects is likely to exist between centres. The aim of this study was to capture current practice in the UK by surveying administration methodologies, imaging and dosimetry protocols, discharge restrictions, workforce and task duration, and treatment-related incidents. A web-based survey with 54 questions was used to investigate PRRT therapy practice. The survey included multiple-choice and free-text questions and was distributed to UK National Health Service centres via professional mailing lists and direct contact. Responses were reviewed and interpreted by a panel of nuclear medicine physicists. Twenty responses were received from National Health Service centres, representing 20/24 UK sites delivering [177Lu]-DOTATATE therapy. Inter-centre variation was observed in administration methods, imaging schedules, dosimetry practice, and discharge restrictions for radiation safety. Most centres (15/20) do not routinely perform dosimetry imaging, primarily due to imaging time and staffing constraints, and lack of interest due to limited perceived clinical benefit. Approximately 59 treatment-related incidents were reported over a 21-month period; contamination and human error were cited as the most common causes. This survey demonstrates variation in the practical aspects and implementation of [177Lu]-DOTATATE therapy in the UK. Variability in behavioural restrictions highlights the need for clear national guidance on performing risk assessments for PRRT, to ensure a consistent patient experience. Free-text responses, particularly those relating to administration methods and incident learning, demonstrate the range of experiences across centres and the potential value of shared learning.

This study aimed to directly compare the diagnostic performance of 18F‑fibroblast activation protein inhibitor (FAPI)‑42 and 18F‑fluorodeoxyglucose (FDG) PET/computed tomography (CT) for detecting distant metastases in nasopharyngeal carcinoma (NPC) and to identify potential pitfall. In this study, 139 NPC patients (30 with distant metastases) underwent both 18F‑FAPI‑42 and 18F‑FDG PET/CT. Diagnostic efficacy (sensitivity, specificity, and accuracy) was evaluated on patient-based and lesion-based analyses for PET alone and integrated PET/CT. Visualization quality and semi-quantitative parameters were compared across different metastatic organs. Risk factors for metastasis were analyzed via univariate and multivariate logistic regression. For detecting distant metastases, 18F‑FAPI‑42 PET alone demonstrated higher sensitivity than 18F‑FDG PET (patient-based: 93.33% vs. 86.67%, P = 0.687; lesion-based: 95.88% vs. 93.13%, P = 0.200), but lower specificity (24.77% vs. 38.53%, P = 0.006; 16.08% vs. 33.33%, P < 0.001) and accuracy (39.57% vs. 48.92%, P = 0.035; 48.33% vs. 57.50%, P < 0.001). However, when interpreted as integrated PET/CT, both tracers achieved equivalent and high diagnostic performance, with no significant differences in sensitivity (95.88% vs. 93.47%), specificity (95.10% vs. 96.74%), or accuracy (both 95.42%). 18F‑FAPI‑42 PET/CT provided superior visualization for bone and pleural metastases. False-positive lesions were common, with 18F‑FAPI‑42 uptake frequently associated with benign bone/joint conditions and 18F‑FDG uptake with lymph node inflammation. Multivariate analysis identified N-stage as the only independent risk factor for distant metastasis (odds ratio = 3.603, P = 0.006). While standalone PET shows differing profiles, integrated 18F‑FAPI‑42 and 18F‑FDG PET/CT provide comparable and high overall accuracy for detecting NPC distant metastases. 18F‑FAPI‑42 offers advantages in visualizing bone and pleural metastases. High false-positive rates for both tracers necessitate careful interpretation with CT correlation. Advanced N-stage is a key predictor of metastatic disease.

Accurate staging is essential in high risk breast cancer to guide management. While flurodeoxyglucose (FDG) PETCT is well established, limited data exist on the cancers role of maximum standardized uptake value (SUVmax) and diffusion-weighted imaging (DWI), especially with limited access to positron emission tomography and magnetic resonance imaging (PETMR). This study evaluates the diagnostic performance of PETMR and correlation between SUVmax and apparent diffusion coefficient (ADC) values in staging these patients. This retrospective study includes 76 biopsy-confirmed treatment-naïve high risk breast cancer patients (triple negative breast cancer and non-triple negative breast cancer) who underwent FDG PETMR (2021-2024). A total of 965 lesions were analysed. Lesion detection, quantitative parameters, and diagnostic performance were assessed, including receiver operating characteristic analysis of SUV-ADC biomarkers. SUVmax showed an inverse correlation with ADCmean (r = -0.41) and ADCmin (r = -0.47), strongest in primary breast tumours and skeletal metastases. The SUVmax/ADCmin ratio effectively graded tumours and correlated with Ki-67 (r = 0.55). FDG PET demonstrated higher specificity (87.8%) than DWI (82.7%), while DWI was more sensitive for detecting small lesions. False positives and false-negative lesions were identified by correlating PET and DWI findings with histopathology (wherever available) or using follow up imaging. Simultaneous PETMR is promising for accurate staging of high risk breast cancer. PET demonstrates higher specificity, whereas DWI improves sensitivity for detecting smaller lesions, particularly in liver, brain, and lungs. A combined FDG PET DWI approach enhances overall diagnostic accuracy and improves lesion characterization and staging. Additionally, the combination of SUVmax and Ki-67 provides a reliable indicator of tumour aggressiveness.

To evaluate the relationships between anatomical, functional, and metabolic parameters and distant metastasis in the primary staging of rectal adenocarcinoma. Seventy-three patients with rectal adenocarcinoma, who underwent pelvic MRI and whole-body 18 F-FDG PET/MRI for staging, were included. Anatomical [T and N stages, extramural venous invasion (EMVI) and circumferential resection margin (CRM) statuses] and functional parameters [apparent diffusion coefficient (ADC) mean (mm²/sn × 10 -6 )] of primary tumor were recorded from pelvic MRI, and metabolic data (maximum standard uptake value (SUV max ), mean SUV (SUV mean ), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and total lesion quotient (TLQ) were recorded from 18 F-FDG PET/MRI. Quantitative parameters combining functional and metabolic data (SUV max /ADC mean , SUV mean /ADC mean , MTV/ADC mean , TLG/ADC mean , TLQ/ADCmean) were calculated. Distant metastases were recorded via 18 F-FDG PET/MRI. To detect lung nodules, supplementary 18 F-FDG PET/CT scans of the thorax were utilized. Relationship between these parameters and distant metastasis, and their ability to predict for distant metastatic disease, were statistically evaluated. In the univariate logistic regression analysis, the SUV max (1.04; 1.0-1.08; P = 0.031), TLG (1.0; 1.0-1.005; P = 0.044), TLG/ADC mean (8.12; 1.04-63.78; P = 0.046), and presence of EMVI (4.13; 1.31-12.98; P = 0.015) (OR; CI; P ) were found to predict distant metastasis. In multivariate regression analysis, SUV max (1.05; 1.0-1.1; P = 0.023) and the presence of EMVI (6.82; 1.64-28.48; P = 0.008) were identified as independent predictors for distant metastatic disease (OR; CI; P ). Significant associations were detected between distant lymph node metastasis and T stage and the presence of EMVI, whereas significant associations were detected between the size of distant lymph node metastases and the SUV max , SUV mean , SUV max /ADC mean , and SUV mean /ADC mean ( P < 0.05). Patients with lung and other organ metastases had significantly greater TLG and TLG/ADC mean values ( P < 0.05). 18 F-FDG PET/MRI allows obtaining anatomical, functional, and metabolic parameters related to the primary tumor in a single session and has the potential to predict information regarding tumor behavior, including distant metastatic spread.

Breast cancer demonstrates heterogeneous clinical behavior, underscoring the need for reliable prognostic biomarkers. Semi-quantitative parameters derived from fluorine‑18 fluorodeoxyglucose PET/CT, including spleen maximum standardized uptake value (SUVmax) and spleen-to-liver SUVmax ratio (SLR), may reflect systemic inflammatory activity and predict outcomes. To assess the prognostic significance of baseline spleen SUVmax and SLR, compared with other PET/computed tomography (CT)-derived parameters, in predicting disease-free survival (DFS) in nonmetastatic breast cancer. Ninety-two female patients with pathologically confirmed invasive breast cancer underwent baseline fluorine‑18 fluorodeoxyglucose PET/CT before treatment. SUVmax values for primary tumor, spleen, and bone marrow were measured, and SLR and bone marrow-to-liver SUVmax ratios were calculated. Associations with clinicopathological features were analyzed using chi-square and ANOVA tests. DFS predictors were evaluated using Cox regression and Kaplan-Meier analysis. Higher spleen SUVmax and SLR were significantly associated with larger tumor size, advanced stage, higher grade, hormone receptor negativity, and triple-negative subtype (P < 0.05). Patients with progressive disease had higher spleen SUVmax (2.93 ± 0.50) and SLR (0.87 ± 0.06) than those with complete remission (P < 0.001). In univariate Cox regression, SLR remained a strong predictor of DFS [hazard ratio = 6.12, 95% confidence interval (CI): 2.05-18.25, P = 0.001]. In multivariate analysis including SLR, Ki-67, stage, nodal status, and molecular subtype, only SLR remained independently significant (hazard ratio = 6.12, 95% CI: 2.05-18.25, P = 0.001). Patients with SLR greater than 0.7083 had significantly shorter mean survival (14.5 vs. 31.6 months, P < 0.001). Baseline SLR is a strong prognostic marker in nonmetastatic breast cancer along with tumor SUVmax and spleen SUVmax, and may aid in risk stratification and treatment planning.