Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors that arise from chromaffin cells of the adrenal medulla and the sympathetic/parasympathetic neural ganglia, respectively. The heterogeneity in its etiology makes PPGL diagnosis and treatment very complex. The aim of this article was to provide practical clinical guidelines for the diagnosis and treatment of PPGLs from a multidisciplinary perspective, with the involvement of the Spanish Societies of Endocrinology and Nutrition (SEEN), Medical Oncology (SEOM), Medical Radiology (SERAM), Nuclear Medicine and Molecular Imaging (SEMNIM), Otorhinolaryngology (SEORL), Pathology (SEAP), Radiation Oncology (SEOR), Surgery (AEC) and the Spanish National Cancer Research Center (CNIO). We will review the following topics: epidemiology; anatomy, pathology and molecular pathways; clinical presentation; hereditary predisposition syndromes and genetic counseling and testing; diagnostic procedures, including biochemical testing and imaging studies; treatment including catecholamine blockade, surgery, radiotherapy and radiometabolic therapy, systemic therapy, local ablative therapy and supportive care. Finally, we will provide follow-up recommendations.
OBJECTIVES
Our goal was to define characteristic patterns of 18F-fluorodeoxyglucose in non-infected patients with ascending aortic prosthetic grafts during the first year after surgery.
METHODS
18F-fluorodeoxyglucose positron emission tomography (PET)/computed tomography (CT) was performed at 3, 6 and 12 months postoperatively in 26 uninfected patients. Clinical, analytical and microbiological (blood culture) assessments were performed to confirm the absence of infection. FDG uptake intensity [measured through maximum standardized uptake values (SUVmax) and the target-to-background ratio] and distribution patterns were obtained. Models of generalized estimating equations were used to assess the evolution of the SUVmax over time. The results were compared to those in our endocarditis-over-ascending-aortic-graft series database. The receiver operating characteristic curves of the control group and the 12-month group were assessed.
RESULTS
All patients showed increased uptake in all areas. The uptake pattern was heterogeneous in 47.4%, 43.5% and 42.3% at 3, 6 and 12 months. The means and standard deviations of the SUVmax in the graft were 4.80 (±0.99), 4.28 (±0.88) and 4.14 (±0.87) at 3, 6 and 12 months after surgery. A comparison of all values obtained in the 6th and 12th months compared to those from the 3rd month revealed a slow decrease that may persist after the first year. The cut-off value of SUVmax of 4.24 had an overall sensitivity of 84.6% and specificity of 57.7% for patients seen at 12 months.
CONCLUSIONS
Non-infected ascending aortic grafts showed no predominant uptake pattern; they also showed increased 18F-fluorodeoxyglucose activity that could persist beyond the first year. Caution is therefore recommended when interpreting PET/CT images obtained during the first year after surgery.
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