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Purpose: Our aim was to assess the prognostic value of [68 Ga]Ga-FAPI-04 positron emission tomography (PET) uptake in PDAC and to evaluate the correlation between in vivo lesional radioactivity with pathological characteristics of pancreatic ductal adenocarcinoma (PDAC). Methods: We retrospectively analyzed treatment‐naïve PDAC patients who underwent preoperative [68 Ga]Ga-FAPI-04 PET/CT followed by pancreatectomy. The tracer uptake was determined as maximum tumor standardized uptake value (SUVmax), FAPI-avid tumor volume (FTV), total lesion FAP expression (TLF) as well total pancreatic uptake (TSUVmax), total FAPI-avid pancreatic volume (FPV), and total pancreatic FAP expression (TPF). Spearman's correlation analysis was performed to evaluate the association between [68 Ga]Ga-FAPI-04 PET/CT imaging and ex vivo immunohistological FAP expression and pathological characteristics of surgical specimens (differentiation, size, vascularity, perineural invasion, and lymph node metastases). Kaplan–Meier and hazard ratio (HR, log-rank) methods were used to evaluate the prognostic value of [68 Ga]Ga-FAPI-04 PET/CT and clinicopathological factors. Results: Thirty-seven surgical PDAC patients were included. The ex vivo expression of FAP was significantly associated with the tumor SUVmax and TLF. FAP expression was more abundant in poorly differentiated PDAC than in well- to moderately differentiated neoplasms. Tumor SUVmax or TLF and pancreatic TSUVmax or TPF were significantly correlated with tumor size, differentiation, and perineural invasion, respectively. SUVmax had a significant independent prognostic value for recurrence-free survival (HR = 2.46, P < 0.05), while [68 Ga]Ga-FAPI-04 TPF predicted overall survival (HR = 12.82, P < 0.05). Conclusion: The in vivo [68 Ga]Ga-FAPI-04 uptake in localized PDAC showed a significant correlation with ex vivo FAP expression and aggressive pathological characteristics. [68 Ga]Ga-FAPI-04 PET/CT also presented a potential for postoperative prognostication of PDAC. Elevated fibroblast activity induced by obstructive pancreatitis might be associated with the patient's survival. [ABSTRACT FROM AUTHOR]

Purpose: To determine the optimal imaging tool for clinical evaluation of pancreatic neoplasm by comparing the performance of 18F-FDG PET/MRI and PET/CT.Procedures: Patients with suspected pancreatic neoplasms underwent PET/MRI and PET/CT in the same day prior to resection or endoscopic ultrasound-guided fine-needle aspiration. Histology served as the golden standard of lesion classification. Visual assessment on lesion type and lesion malignancy via PET/MRI and PET/CT images was compared. Standard uptake values (SUVs) of PET images from the two scanners were measured and their correlations were further evaluated.Results: Thirty-nine patients were included for the final analysis. In visual assessment, we found MRI achieved better performance than CT in differentiating solid and cystic neoplasms, with accuracy of 100% vs. 87%, respectively. In visual malignancy diagnosis, the accuracy of PET/CT was 92.3% for overall lesions and 90.9% for cysts, while the accuracy of PET/MRI was 92.3% and 86.4%, respectively. Besides, semi-quantitative analysis achieved better specificity than visual assessment for both hybrid modalities (100% vs. 87.5% for PET/CT; 100% vs. 81.5% for PET/MR). Furthermore, strong correlation of SUV was found between PET/CT and PET/MRI, with Pearson's correlation coefficients > 0.82.Conclusions: In this study, we found PET/MRI and PET/CT, both using 18F-FDG as tracer, had comparable overall performance in identification of pancreatic neoplasms. Interestingly, for patients who had suspected pancreatic neoplasm but invisible FDG uptake, PET/MRI had shown exceptionally better performance, probably because MR images could detect tiny abnormal structures to improve diagnosis. [ABSTRACT FROM AUTHOR]

This study discusses the interannual variation of spring precipitation in Northeast China (NECSP) from 1980 to 2016 and its relationship with Arctic sea ice based on observation data and numerical experiments. The observed results reveal that the leading mode of NECSP mainly exhibits a homogenous pattern with a significant interannual variation. The NECSP has a significant negative correlation with the preceding winter Barents Sea ice concentration (BSIC) at the interannual scale. In the preceding winter, the decreased BSIC resulted in positive geopotential height anomalies over the polar region, which could weaken the polar vortex and westerly winds, forming a cyclonic anomaly indirectly over West Siberia. The circulation anomalies resulted in a zonal dipole pattern of preceding winter snow water equivalent (SWE) anomalies in the mid‐high latitudes of Eurasia with less SWE over Eastern Europe and more SWE over West Siberia. The SWE anomalies in winter could persist to the subsequent spring and facilitate more precipitation over Northeast China (NEC) by local thermal processes affecting circulation anomalies over Eurasia. On the other hand, the negative preceding winter BSIC anomalies can persist to spring, increasing the NECSP by strengthening the cyclonic anomalies over NEC. In this study, the response of the atmosphere to the thermal effect of SWE is further verified by using the linear baroclinic model (LBM). The response of NECSP to BSIC loss is tested by using the Community Atmosphere Model version 5.3 (CAM5.3). [ABSTRACT FROM AUTHOR]