Purpose: We performed a systematic review and meta-analysis to investigate the efficacy of peptide receptor radionuclide therapy (PRRT) by using radiolabeled somatostatin analogues in high grade gastro-entero-pancreatic neoplasms (GEP-NEN).
Methods: All clinical studies published up to March 2025, including patients with grade 3 (G3) GEP-NEN treated with [177Lu] Lu-DOTA-TATE and/or [90Y] Y-SSA, were identified based on systematic searches in the PubMed and Embase databases. Eligible studies had to report at least one of the following outcomes: 1) response to therapy evaluated according to RECIST (version 1.1 as complete response, partial response, stable disease, progressive disease; 2) median progression free survival (PFS) with 95% confidence intervals (CI); 3) median overall survival (OS) with 95% CI. Objective response rate (ORR) and disease control rate (DCR) were considered as primary outcomes.
Results: The final analysis included 7 studies accounting for a total of 317 patients with G3 disease (ranging from 18 to 112). Six studies evaluated response to therapy according to RECIST in 288 patients, and in 4 of them patients were also stratified according to ki67 values. The pooled ORR and DCR were 34% (95% CI: 22-46) and 64% (95% CI: 52-76), respectively. The funnel plot indicated no publication bias among these studies. Five studies reported in 239 patients median PFS with 95% CI, with a pooled estimate of 13.88 (95% CI: 10.33-18.64) months. Three studies fully reported in 174 patients median OS with 95% CI, with a pooled estimate of 29.95 (95% CI: 19.80-45.30) months.
Conclusions: In patients with G3 GEP-NEN, PRRT may provide substantial disease control and response rates, and it seems able to delay the progression of the disease.
Background: Intra-abdominal desmoid tumours (IADT) can closely mimic gastrointestinal stromal tumours (GISTs), particularly in recurrence and metastases. However, differentiating these two diseases using radiological methods remains challenging. This study aimed to investigate the value of [18F]FAPI-42 PET/CT in differentiating IADT and GISTs compared to [18F]FDG PET/CT.
Methods: This study retrospectively included a total of 24 patients (12 patients with IADT and 12 patients with recurrent/metastatic GISTs) who underwent two separate PET/CT scans using [18F]FAPI-42 and [18F]FDG, respectively. The differences in tumour SUVmax on [18F]FAPI-42 PET/CT (SUVmax-FAPI) and [18F]FDG PET/CT (SUVmax-FDG) and the ratio of tumour SUVmax on FAPI PET/CT to SUVmax on FDG PET/CT [SUVmax ratio (FAPI/FDG)] were compared between IADT and GISTs. Receiver operating characteristic (ROC) curve analyses were performed to evaluate the diagnostic performance of these parameters in differentiating IADTs from GISTs. Immunohistochemistry was used to verify FAP expression in all IADT lesions and GISTs lesions.
Results: The SUVmax of IADTs on [18F]FAPI-42 PET/CT was significantly higher than that of GISTs [8.8 (7.2, 10.6) vs. 3.9 (2.8, 7.6), P = 0.045], whereas the SUVmax of IADTs on [18F]FDG PET/CT was significantly lower than that of GISTs [2.5 (1.9, 3.5) vs. 6.1 (3.6, 8.3), P = 0.007]. The SUVmax ratio (FAPI/FDG) of IADTs was significantly higher than that of GISTs [3.3 (2.2, 4.1) vs. 0.8 (0.3, 1.4), P < 0.001]. SUVmax-FAPI, SUVmax-FDG, and the SUVmax ratio (FAPI/FDG) achieved AUCs of 0.743, 0.819, and 0.896, with corresponding accuracies of 75.0%, 83.3%, and 87.5%, respectively, for distinguishing IADT from GISTs. Immunohistochemistry revealed significantly higher FAP expression in IADTs compared to GISTs (P = 0.002), with most IADTs showing strong (3+) staining (8/12, 66.7%), while GISTs primarily demonstrated weak (1+) or no staining (7/12, 58.3%).
Conclusion: The distinct uptake characteristics of [18F]FAPI-42 and [18F]FDG observed in IADTs and GISTs provide preliminary evidence that these two tracers may offer complementary diagnostic information when evaluating desmoid tumours that mimic recurrent or metastatic GISTs.
Purpose: Inflammatory Bowel Diseases (IBD) comprise ulcerative colitis (UC) and Crohn's disease (CD). Management of IBD requires assessment of disease activity, severity, extent and complications. Here, we describe the signal behavior of both CD and UC in 68Gallium- fibroblast activation protein inhibitor-based radiopharmaceuticals-46-positron emission tomography (68Ga-FAPI-46-PET) and evaluate the potential of 68Ga-FAPI-46-PET for activity assessment in IBD.
Patients and methods: This analysis includes data of 43 IBD patients and 43 control patients examined by 68Ga-FAPI-46-PET/computed tomography (CT). Disease activity of IBD patients was assessed by colonoscopy. FAPI-positive gastrointestinal tract (GIT)-findings and healthy appearing GI structures were contoured. Non-IBD related FAPI-positive GIT-findings were ruled out by interdisciplinary consensus. Static and dynamic PET-parameters of FAPI-positive IBD lesions and healthy appearing GI structures were extracted and PET signalling was analyzed with respect to IBD subtype and disease activity.
Results: We examined 20 CD patients and 23 UC patients (29 with active, 14 with inactive disease). FAPI-uptake in most healthy appearing GI structures of IBD patients was significantly increased compared to controls. Of 80 FAPI-positive GIT-findings, 14 were ruled out as non-IBD related and 66 FAPI-positive IBD lesions were analyzed. We observed equally high lesional FAPI-uptake in CD and UC. All patients with active disease showed at least one intensively FAPI-positive IBD lesion, while only 4/14 patients with inactive disease showed any FAPI-positive IBD lesion. Lesional and patientwise FAPI-uptake was significantly higher in active than in inactive disease. FAPI-positive IBD lesions showed a characteristic kinetic behaviour with two types of uptake patterns - one showing a continuous increase and the other an early peak followed by a plateau.
Conclusion: 68Ga-FAPI-46-PET/CT appears promising for assessing disease activity in terms of fibroblast activation in both CD and UC.
Purpose: To assess machine learning (ML) classifiers trained on harmonised multicentre ¹²³I-mIBG planar scintigraphy for differentiating Parkinson's disease (PD) from non-PD parkinsonian syndromes and to determine whether early imaging alone may ensure accurate discrimination.
Methods: This retrospective study included patients with suspected PD who underwent early (~ 15 min) and delayed (~ 240 min) imaging and received a definitive diagnosis after ≥ 12 months. Harmonised region of interest (ROI) placement and ComBat correction were applied. Early and late heart-to-mediastinum (H/M) ratios and washout rate (WR) were calculated. Differences were tested by Mann-Whitney U test, and cut-points identified by ROC analysis. Logistic regression, Gaussian naïve Bayes, and support vector machine were trained on these features with Z-score normalisation and synthetic minority oversampling technique (SMOTE).
Results: 127 patients were analysed (85 PD, 42 non-PD). Early and late H/M ratios were significantly lower in PD than non-PD (early H/M 1.45 ± 0.20 vs. 1.80 ± 0.20; late H/M 1.33 ± 0.22 vs. 1.68 ± 0.21; both p < 0.001). WR was modestly higher in PD (8.74 ± 5.76% vs. 6.49 ± 6.19%, p = 0.024). Optimal cut-points for PD were: early H/M ≤ 1.62 (accuracy 80.3%, sensitivity 83.3%, specificity 78.8%, and AUC 0.878), late H/M ≤ 1.52 (83.5%, 83.3%, 83.5% and 0.866) and WR ≥ 6.03% (70.1%, 70.6%, 69.0% and 0.645). ML achieved mean accuracy 78.9-80.7%, sensitivity 81.9-84.0%, specificity 68.6-78.0%, and AUC 0.850-0.875.
Conclusion: Classifiers trained on ¹²³I-mIBG semi-quantitative indices accurately distinguished PD from non-PD. Early H/M ratio alone provided excellent discrimination, supporting early-imaging; prospective validation is warranted.
Purpose: Recent advancements in autoimmune encephalitis (AE) have enhanced diagnosis and management, but predicting long-term outcomes remains challenging. This study aims to evaluate longitudinal changes in brain [18F]FDG PET patterns in AE patients to identify specific regional metabolic variations and predict clinical outcomes.
Methods: This longitudinal study compared brain [18F]FDG PET scans of 22 AE patients at baseline (BS) and after treatment follow-up (FU) using voxel-wise paired t-tests. Significant clusters with at least 100 voxels and p < 0.05 were identified and designated as volumes of interest (VOIs). The VOI values were correlated with main clinical outcomes using partial Spearman's tests, and their prognostic significance was assessed through regression models.
Results: Three VOIs showed significant metabolic changes between baseline (BS) and follow-up (FU) assessments. VOI-A, which was relatively hypermetabolic at BS, included the caudate-thalamus-parahippocampal region, right amygdala, and anterior cingulate cortex. VOI-B1 and VOI-B2, relatively hypometabolic at BS, corresponded to the right fusiform gyrus, precuneus, and temporo-parietal cortex, respectively. Poorer metabolic recovery in all VOIs to normalcy correlated with greater disability (mRS) in both acute and post-therapy phases. Lower metabolism in BS VOI-B1 predicted higher Clinical Assessment Scale in Autoimmune Encephalitis (CASE) score at FU and relapses, while lower age was a significant predictor of escalation to second-line treatment.
Conclusions: Longitudinal [18F]FDG PET reveals distinct regional metabolic changes paralleling clinical recovery post-treatment in AE. Temporo-parietal metabolism correlates with relapses, clinical severity, and functional impairment, highlighting [18F]FDG PET as a biological tracker of disease activity throughout AE and its prognostic value.

