Context Despite the growing evidence of the clinical value of somatostatin receptor (SSTR) PET in the evaluation of neuroendocrine tumors/NET, its role remains to be clarified at different time points in the MEN1 patient journey. The rareness of the disease is however a significant impediment to prospective clinical trials. Objectives The goals of the study were to assess the indications and value of SSTR PET/CT in MEN1 patients. Methods We retrospectively included patients from 7 French expert centres for whom data on SSTR PET/CT and morphological imaging performed at the same period were available. Detection rates of PET study were analysed. Results One hundred eight patients were included. SSTR PET/CT was performed at screening (n=33), staging (n=34), restaging (n=37) and for PRRT selection (n=4). PET detected positive pancreatic lesions in 91% of cases at screening, with comparable results to MRI but superiority to CT (P=0.049). Metastases (mostly LN) were present at the screening phase in 28% of cases, possibly due to the suboptimal value of screening morphological imaging in the assessement of nodal metastases and/or a long delay between imaging studies. SSTR PET/CT was considered as superior or complementary to the reference standard in the assessment of LN or distant metastases in the vast majority of cases and regardless of the clinical scenario. Conclusion This study shows the potential added value of SSTR PET in the assessment of MEN1-associated NETs and provides a great impetus towards its implementation in the evaluation of MEN1 patients.

To compare the respective value of 68 Ga-DOTATOC and 18 F-DOPA PET/CT for initial staging or pre-surgical work-up of patients with small intestine neuroendocrine tumors (SiNET).Methods. This is a retrospective, multicenter, non-interventional investigation involving 53 nonoperated SiNET patients who underwent both 68 Ga-DOTATOC and 18 F-DOPA PET/CT within a 6-months interval without therapeutic intervention or change between the two PET/CT studies.Detection rate (DR %) was calculated according to per-region and per-lesion analyses. Sensitivity for primary tumor detection was assessed in 37 operated patients taking surgical results (76 SiNET) as diagnostic gold standard.Results. Each of 68 Ga-DOTATOC PET/CT and 18 F-DOPA PET/CT individually identified at least one primary SiNET in 92% (34/37) of the patients. Tumor intestinal multifocality was confirmed by histology in 8 patients. 68 Ga-DOTATOC and 18 F-DOPA PET/CT were concordant positive for tumor multifocality in 5, discordant positive in 2, and concordant negative in 1 case. DR % for subdiaphragmatic nodal metastases on per-region-based analysis was 91 % and 98 % for 68 Ga-DOTATOC and 18 F-DOPA PET/CT, respectively (p=0.18). 18 F-DOPA PET/CT detected a higher number of abnormal subdiaphragmatic nodes (p=0.009). Regarding mesenteric nodes only, 18 F-DOPA PET/CT detected more positive regions (p=0.005) and nodal lesions (p=0.003) than 68 Ga-DOTATOC PET/CT, including nodes located at the origin of mesenteric vessels. For detection of distant metastases, 68 Ga-DOTATOC and 18 F-DOPA PET/CT performed equally on a per-regionbased analysis. As compared to 68 Ga-DOTATOC, 18 F-DOPA PET/CT detected more hepatic (p<0.001), peritoneal (p<0.001), and lung metastases (p<0.001).Conclusions. 18 F-DOPA PET/CT detects more lesions than 68 Ga-DOTATOC PET/CT in studied patients. Their respective role should be discussed in terms of disease staging and treatment selection.

Delaunay A and Lebtahi R (2022) Concepts and methods for the dosimetry of radioembolisation of the liver with Y-90-loaded microspheres.

We report the case of a 62-year-old woman with previous history of stage III Hodgkin lymphoma. Routine follow-up CT scan revealed 2 years after end of treatment the appearance of mediastinal nodes, suspected of lymphoma recurrence. An 18F-FDG PET/CT was performed showing hypermetabolic mediastinal lymph nodes with diffuse symmetric osteomedullar hypermetabolism of pelvis and scapulae. In the hypothesis of either recurrence or multisystemic inflammatory disorder, bone marrow and lymph node biopsies were performed, revealing the presence of noncaseating epithelioid cell granulomas, leading to the diagnosis of multisystemic sarcoidosis. This case illustrates the sarcoidosis-lymphoma syndrome.