Human brown adipose tissue (BAT) presence, metabolic activity and estimated mass are typically measured by imaging [18F]fluorodeoxyglucose (FDG) uptake in response to cold exposure in regions of the body expected to contain BAT, using positron emission tomography combined with x-ray computed tomography (FDG-PET/CT). Efforts to describe the epidemiology and biology of human BAT are hampered by diverse experimental practices, making it difficult to directly compare results among laboratories. An expert panel was assembled by the National Institute of Diabetes and Digestive and Kidney Diseases on November 4, 2014 to discuss minimal requirements for conducting FDG-PET/CT experiments of human BAT, data analysis, and publication of results. This resulted in Brown Adipose Reporting Criteria in Imaging STudies (BARCIST 1.0). Since there are no fully-validated best practices at this time, panel recommendations are meant to enhance comparability across experiments, but not to constrain experimental design or the questions that can be asked.

Raman spectroscopy is an optical imaging modality which analyses the Raman effect in which energy is exchanged between light and matter. Although Raman spectroscopy has been widely used for chemical and molecular analysis, its use in clinical applications has been hindered by the inherently weak nature of the Raman effect. Raman-silica-gold-nanoparticles (R-Si-Au-NPs) overcome this limitation by producing high Raman signals via Surface Enhanced Raman Scattering. Targeted polyethylene glycol (PEG)-ylated R-Si-Au-NPs (e.g. PEG-R-Si-Au-NPs labeled with an affibody which binds specifically to the epidermal growth factor receptor) are currently being designed to detect colorectal cancer after administration into the bowel lumen. With this approach, PEG-R-Si-Au-NPs are not expected to enter the systemic circulation and would be removed from the body via defecation. We examined the acute toxicity and biodistribution of core PEG-R-Si-Au-NPs after different routes of administration in mice. After intravenous administration, PEG-R-Si-Au-NPs were removed from the circulation by marcophages in the liver and spleen (i.e. the reticuloendothelial system). At 24 hours, PEG-R-Si-Au-NPs elicited a mild inflammatory response and an increase in oxidative stress in the liver, which subsided by 2 weeks. No evidence of significant toxicity was observed by measuring clinical, histological, biochemical or cardiovascular parameters for 2 weeks. Notably, after administration per rectum, we observed no significant bowel or systemic toxicity and no PEG-R-Si-Au-NPs were detected systemically. Although additional studies are required to investigate the long-term effects of PEG-R-Si-Au-NPs, these initial results support the idea that they can be safely used in living subjects, especially when administered rectally.

F-FES PET imaging could serve as a pharmacodynamic biomarker for patients treated with ER-directed therapy.

The results of this study demonstrate the superiority of (68)Ga-DOTATATE PET/CT in the localization of sporadic metastatic PPGLs compared to all other functional and anatomical imaging modalities, and suggest modification of future guidelines towards this new imaging modality.