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Wide-field surgical excision reduces the chance of residual disease, but can also lead to disfigurement and devastating morbidities when resection is close to critical structures. We hypothesize that near-infrared fluorescence (NIRF) imaging can enable accurate detection of tumor margins for image-guided resection. An orthotopic model of human prostate cancer (PCa) was used to assess primary tumor margins using a NIRF-labeled antibody against epithelial cell adhesion molecule (EpCAM). PCa cells stably expressing far red fluorescent gene reporter, iRFP, enabled colocalization with NIRF signals for direct assessment of tumor margins. Using receiver operating characteristic analysis, far red fluorescence was validated against standard pathology of primary and metastatic lesions with >96 % accuracy. Primary tumor margins were more accurately detected by quantitative NIRF imaging using the EpCAM-targeting antibody as compared to a NIRF-labeled isotype control antibody. NIRF molecular imaging may enable real-time and accurate assessment of tumor margins.

The presence of brown adipose tissue responsible for thermogenic energy dissipation has been revealed in adult humans and has high clinical importance. Owing to limitations of current methods for brown adipose tissue detection, analysing the abundance and localization of brown adipose tissue in the body has remained challenging. Here we screen a combinatorial peptide library in mice and characterize a peptide (with the sequence CPATAERPC) that selectively binds to the vascular endothelium of brown adipose tissue, but not of intraperitoneal white adipose tissue. We show that in addition to brown adipose tissue, this peptide probe also recognizes the vasculature of brown adipose tissue-like depots of subcutaneous white adipose tissue. Our results indicate that the CPATAERPC peptide localizes to brown adipose tissue even in the absence of sympathetic nervous system stimulation. Finally, we demonstrate that this probe can be used to identify brown adipose tissue depots in mice by whole-body near-infrared fluorescence imaging.