Comparison of early and late 68Ga-FAPI-46-PET in 33 patients with possible recurrence of pancreatic ductal adenocarcinomas.

Positron emission tomography with 68Gallium (68Ga) labeled inhibitors of fibroblast activation protein (68Ga-FAPI-PET) is a promising imaging technique for patients with recurrent pancreatic ductal adenocarcinomas (PDAC). To date, it is not clear if different acquisition timepoints for 68Ga-FAPI-PET may result in comparable imaging information and if repetitive 68Ga-FAPI-PET imaging may add diagnostic value to single timepoint acquisition for recurrent PDAC. Here we analyzed retrospectively early (20 min p.i.) and late (60 min p.i.) 68Ga-FAPI-PET imaging using FAPI-46 of 33 patients with possible recurrence of PDAC concerning detection rates and uptake over time of local recurrences, metastases, inflammatory lesions of the pancreas, cholestatic lesions of the liver and reactive tissue. 33 patients with histologically confirmed PDAC after complete or partial resection of the pancreas and possible recurrence were examined by 68Ga-FAPI-46-PET acquired 20- and 60-min post injection (p.i.) of the radiotracer. FAPI-positive lesions were classified as local recurrences, metastases, inflammatory lesions of the pancreas (ILP), cholestatic lesions of the liver and reactive tissue based on histology, PET- and CT-morphology and clinical information. Lesions were contoured, and standardized uptake values (SUVmax and SUVmean) and target-to-background ratios (TBR) were analyzed for both acquisition timepoints. In total, 152 FAPI-positive lesions (22 local relapses, 47 metastases, 26 inflammatory lesions of the pancreas, 28 reactive tissues, and 29 cholestatic lesions) were detected. Detection rates for the early and late acquisition of 68Ga-FAPI-46-PET were almost identical except cholestatic lesions, which showed a higher detection rate at early imaging. SUV parameters and TBRs of ILP significantly decreased over time. Cholestatic lesions showed a tendency towards decreasing uptake. All other types of lesions showed relatively stable uptake over time. Early and late acquisition of 68Ga-FAPI-PET results in comparable imaging information in patients with possible recurrence of PDAC. Two timepoint imaging offers additional diagnostic potential concerning differential diagnoses.

Risk factors for malignant transformation of hepatocellular adenoma to hepatocellular carcinoma: protocol for systematic review and meta-analysis.

INTRODUCTION: Hepatocellular adenomas (HCAs) are solid liver tumours that are usually found incidentally during routine medical check-ups. Multiple modifiable and non-modifiable factors constitute a risk for the malignant transformation of HCAs to hepatocellular carcinoma (HCC), which has emerged to be one of the fastest growing causes of cancer-related mortality globally. This study protocol for a planned systematic review and meta-analysis documents the methodological approach to identify risk factors and their risk estimates for the transformation from HCA to HCC. METHODS AND ANALYSIS: Two independent reviewers will systematically search and extract data from studies in patients of all ages published between January 1970 and June 2021 on PubMed, MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature, Scopus Web of Science, Ovid, The Cochrane Hepatobiliary Group Controlled Trials Register and The Cochrane Central Register of Controlled Trials by using an a priori defined search strategy. Study quality will be rated with the National Institute of Health quality assessment tools. Disagreements will be resolved by consensus with a third independent reviewer. The primary outcome will be the odds ratio (OR) of developing HCC in patients with prediagnosed HCA depending on the exposure to risk factors. HCC diagnosis must be inferred based on imaging techniques or pathology. We will use R V.4.0.2 to conduct meta-analyses and generate pooled ORs based on random effects models. Results will be presented as forest plots. Cochran's Q and I2 test will be performed to assess heterogeneity between included studies. Funnel plots and Egger's weighted regression will be used to evaluate publication bias. ETHICS AND DISSEMINATION: No ethical approval is required as we will use and analyse data from previously published studies in which informed consent was obtained. The results will be disseminated in a peer-reviewed journal on completion. PROSPERO REGISTRATION NUMBER: CRD42020206578.