Objectives: unexpected detection of axillary lymphadenopathy (AxL) in cancer patients (Pts) represents a real concern during COVID-19 vaccination era. Benign reactions may take place after vaccine inoculation, confounding image interpretation in patients undergoing F-18-FDG, F-18-Choline and Ga-68-DOTATOC PET/CT. It may simulate loco-regional metastases/disease. To assess PET/CT findings after COVID-19 vaccination in cancer patients and the consequent impact on their management. Methods: we evaluated 333 patients undergoing PET/CT (257 F-18-FDG, 54 F-18-Choline and 23 Ga-68 DOTATOC) scans after first vaccination with mRNA vaccine (Pfizer-BioNTech). Uptake index (SUVmax) of suspected AxL was defined significant when the ratio >1.5 as compared to the contralateral inoculation site. Besides, co-registered CT (Co-CT) features of target lymph-nodes were evaluated. Nodes with aggregate positivity were further investigated.Results: overall, the prevalence of apparently positive lymph-nodes on PET scans was 17.1% during vaccination era. 107 Pts had undergone PET/CT before COVID-19 pandemic and only 3 shown reactive lymph-nodes with a prevalence of 2.8% (p<0.001 as compared to vaccination era). 84.2% exhibited benign characteristics on Co-CT images and only 9 Pts needed additional appraisal. Conclusions: the correct interpretation of images is crucial to avoid unnecessary management changes and to rule out invasive procedures in cancer Pts undergoing diagnostics. An accurate anamnestic interview and the precise assessment of nodes’ Co-CT characteristics when performing PET/CT may help to address the diagnostic hypothesis.
Background We retrospectively aimed to assess the prognostic significance of somatostatin receptor (SSTR) standardized uptake value (SUVmaxsstr), SSTR representative tumor volume (RTVsstr) and total lesion SSTR expression (TLsstr) obtained by [68Ga]Ga-edotreotide PET/CT ([68Ga]Ga-SSTR PET/CT) in patients with primary gastroenteropancreatic neuroendocrine tumors (GEP-NET) before surgery. Material and Methods We analyzed patients who underwent [68Ga]Ga-SSTR PET/CT 3-6 weeks before surgery from February 2020 to April 2022. The mean SUVmaxsstr value, the RTVsstr (cm3; 42% threshold) and the TLsstr (g) were registered. Thereafter the patients were followed up 10.3 months (range 3-27). The PET/CT results were compared to the event free survival (EFS). Results Forty-two patients (61 ± 13 years) have been enrolled. At multivariate analysis only RTVsstr values were predictive. The Kaplan-Meier survival analysis for RTVsstr showed a significant better EFS in patients presenting lower values as compared to those having greater ( P = .003, log-rank test). SUVmaxsstr was not suitable for predicting EFS, TLsstr mildly. Conclusion RTVsstr represents a valuable volumetric parameter able to predict the outcome in GEP-NET patients who underwent surgery. The magnitude of the SSTR representative tumor burden holds a predominant value for determining the response to therapy in GEP-NET patients before surgery, rather than the maximal SSTR representation at single voxel.
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