Diagnostic Potential of Supplemental Static and Dynamic 68Ga-FAPI-46 PET for Primary 18F-FDG-Negative Pulmonary Lesions.

PET using 68Ga-labeled fibroblast activation protein (FAP) inhibitors (FAPIs) holds high potential for diagnostic imaging of various malignancies, including lung cancer (LC). However, 18F-FDG PET is still the clinical gold standard for LC imaging. Several subtypes of LC, especially lepidic LC, are frequently 18F-FDG PET-negative, which markedly hampers the assessment of single pulmonary lesions suggestive of LC. Here, we evaluated the diagnostic potential of static and dynamic 68Ga-FAPI-46 PET in the 18F-FDG-negative pulmonary lesions of 19 patients who underwent surgery or biopsy for histologic diagnosis after PET imaging. For target validation, FAP expression in lepidic LC was confirmed by FAP immunohistochemistry. Methods: Hematoxylin and eosin staining and FAP immunohistochemistry of 24 tissue sections of lepidic LC from the local tissue bank were performed and analyzed visually. Clinically, 19 patients underwent static and dynamic 68Ga-FAPI-46 PET in addition to 18F-FDG PET based on individual clinical indications. Static PET data of both examinations were analyzed by determining SUVmax, SUVmean, and tumor-to-background ratio (TBR) against the blood pool, as well as relative parameters (68Ga-FAPI-46 in relation to18F-FDG), of histologically confirmed LC and benign lesions. Time-activity curves and dynamic parameters (time to peak, slope, k 1, k 2, k 3, and k 4) were extracted from dynamic 68Ga-FAPI-46 PET data. The sensitivity and specificity of all parameters were analyzed by calculating receiver-operating-characteristic curves. Results: FAP immunohistochemistry confirmed the presence of strongly FAP-positive cancer-associated fibroblasts in lepidic LC. LC showed markedly elevated 68Ga-FAPI-46 uptake, higher TBRs, and higher 68Ga-FAPI-46-to-18F-FDG ratios for all parameters than did benign pulmonary lesions. Dynamic imaging analysis revealed differential time-activity curves for LC and benign pulmonary lesions: initially increasing time-activity curves with a decent slope were typical of LC, and steadily decreasing time-activity curve indicated benign pulmonary lesions, as was reflected by a significantly increased time to peak and significantly smaller absolute values of the slope for LC. Relative 68Ga-FAPI-46-to-18F-FDG ratios regarding SUVmax and TBR showed the highest sensitivity and specificity for the discrimination of LC from benign pulmonary lesions. Conclusion: 68Ga-FAPI-46 PET is a powerful new tool for the assessment of single 18F-FDG-negative pulmonary lesions and may optimize patient stratification in this clinical setting.

[Is there an unmet need to establish a young talent section "Young DGN" within the German Society of Nuclear Medicine (DGN)? - Results of a 2021/2022 web-based survey among German Nuclear Medicine professionals]. / Besteht der Bedarf zur Gründung einer Nachwuchsorganisation "Young DGN" innerhalb der Deutschen Gesellschaft für Nuklearmedizin (DGN)? Ergebnisse einer webbasierten Umfrage in der deutschen Nuklearmedizin 2021/2022.

AIM: In various medical societies, dedicated young talent sections provide an important basis for promoting young members. However, the German Society of Nuclear Medicine (DGN) had not yet implemented such a section. Therefore, the aim of this work was to assess the opinion of nuclear medicine professionals in Germany on establishing a young talent section within the DGN ("Young DGN"). METHODS: An initiative group of young DGN members developed a survey questionnaire comprising 18 questions. The questionnaire was initially sent as a PDF to the members of the DGN University Committee (Hochschulausschuss) by e-mail on 10/12/2021. As an online survey, the questionnaire was then emailed at four additional time points between 12/23/2021 and 3/18/2022 via the DGN eBrief and on 2/23/2022 to the members of the mailing list of the Berufsverband Deutscher Nuklearmediziner (BDN). RESULTS: The survey closed on 3/31/2022 with 111 responses (n=104 online surveys, n=7 PDFs). The median age of participants was 32.5 years (range, 20-80). 86% of participants indicated that they were interested in a Young DGN section, of which 67% were willing to participate. 79% indicated that nuclear medicine was an exciting field for them. 96% expressed interest in additional education offers and 60% in the establishment of a mentoring program. 75% believed that Young DGN would improve the visibility of the specialty. CONCLUSION: The survey results indicate strong support for the establishment of a young talent section within the DGN among nuclear medicine professionals in Germany. A large proportion of those who participated in the survey would envision active involvement. There was a particular consensus on the desire to expand the range of education and training activities.

Development and Validation of an Automatic Segmentation Algorithm for Quantification of Intracerebral Hemorrhage.

BACKGROUND AND PURPOSE: ABC/2 is still widely accepted for volume estimations in spontaneous intracerebral hemorrhage (ICH) despite known limitations, which potentially accounts for controversial outcome-study results. The aim of this study was to establish and validate an automatic segmentation algorithm, allowing for quick and accurate quantification of ICH. METHODS: A segmentation algorithm implementing first- and second-order statistics, texture, and threshold features was trained on manual segmentations with a random-forest methodology. Quantitative data of the algorithm, manual segmentations, and ABC/2 were evaluated for agreement in a study sample (n=28) and validated in an independent sample not used for algorithm training (n=30). RESULTS: ABC/2 volumes were significantly larger compared with either manual or algorithm values, whereas no significant differences were found between the latter (P<0.0001; Friedman+Dunn's multiple comparison). Algorithm agreement with the manual reference was strong (concordance correlation coefficient 0.95 [lower 95% confidence interval 0.91]) and superior to ABC/2 (concordance correlation coefficient 0.77 [95% confidence interval 0.64]). Validation confirmed agreement in an independent sample (algorithm concordance correlation coefficient 0.99 [95% confidence interval 0.98], ABC/2 concordance correlation coefficient 0.82 [95% confidence interval 0.72]). The algorithm was closer to respective manual segmentations than ABC/2 in 52/58 cases (89.7%). CONCLUSIONS: An automatic segmentation algorithm for volumetric analysis of spontaneous ICH was developed and validated in this study. Algorithm measurements showed strong agreement with manual segmentations, whereas ABC/2 exhibited its limitations, yielding inaccurate overestimations of ICH volume. The refined, yet time-efficient, quantification of ICH by the algorithm may facilitate evaluation of clot volume as an outcome predictor and trigger for surgical interventions in the clinical setting.