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Purpose: To ensure comparable PET/CT image quality between or within centres, clinical inter-system performance comparisons following European Association of Nuclear Medicine Research Ltd. (EARL) guidelines is required. In this work the performance of the long axial field-of-view Biograph Vision Quadra is compared to its predecessor, the short axial field-of-view Biograph Vision., Procedures: To this aim, patients with suspected tumour lesions received a single weight-based (3 MBq/kg) 2-deoxy-2-[ 18 F]fluoro-D-glucose injection and underwent routine clinical ( ∼ 15 min) scans on the Vision and 3-min scans on the Quadra in listmode in balanced order. Image quality (IQ), image noise (IN), and tumour demarcation (TD) were assessed visually by four nuclear medicine physicians using a 5-point Likert scale and semiquantitative analysis was performed using standardised uptake values (SUVs). Inter-reader agreement was tested using Wilcoxon's signed rank test and the SUVs were statistically compared using a paired t-test., Results: Twenty patients (mean age, 60 years ± 8.8 [standard deviation], 16 male) were enrolled. Inter-reader agreement ranged from good to very good for IQ and IN (0.62 ≤ W ≤ 0.81), and fair for TD (0.29 ≤ W ≤ 0.39). Furthermore, a significant difference was found for TD (p = 0.015) between the systems, showing improved TD for the Quadra., Conclusion: This study demonstrates that the Quadra can be used in routine clinical practice with multiple PET/CT systems or in multicentre studies. This system provides comparable diagnostic image quality and semiquantitative accuracy, improved TD, and has the advantage of shorter scan durations., (© 2024. The Author(s).)

Purpose: Estrogen receptors (ER) are implicated in psychiatric disorders. We assessed if ER availability in the human brain could be quantified using 16α-[ 18 F]-fluoro-17β-estradiol ([ 18 F]FES) positron emission tomography (PET)., Procedures: Seven post‑menopausal women underwent a dynamic [ 18 F]FES PET scan with arterial blood sampling. A T1-weighted MRI was acquired for anatomical information. After one week, four subjects received a selective ER degrader (SERD), four hours before the PET scan. Pharmacokinetic analysis was performed using a metabolite-corrected plasma curve as the input function. The optimal kinetic model was selected based on the Akaike information criterion and standard error of estimated parameters. Accuracy of Logan graphical analysis and standardized uptake value (SUV) was determined via correlational analyses., Results: The reversible two-tissue compartment model (2T4k) model with fixed K 1 /k 2 was preferred. The total volume of distribution (V T ) could be more reliably estimated than the binding potential (BP ND ). A high correlation of V T with Logan graphical analysis was observed, but only a moderate correlation with SUV. SERD administration resulted in a reduced V T in the pituitary gland, but not in other regions., Conclusions: The optimal quantification method for [ 18 F]FES was the 2T4k with fixed K 1 /k 2 or Logan graphical analysis, but specific binding was only observed in the pituitary gland., (© 2024. Crown.)