Feasibility of Using an Enzymatically Activatable Fluorescence Probe for the Rapid Evaluation of Pancreatic Tissue Obtained Using Endoscopic Ultrasound-Guided Fine Needle Aspiration: a Pilot Study

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is the most reliable method for the histological diagnosis of pancreatic tumors. Rapid on-site fluorescence-guided histological diagnosis was evaluated by topically applying an enzymatically activatable probe onto the EUS-FNA samples; the probe fluoresces in the presence of gamma-glutamyltranspeptidase (GGT). We evaluated GGT expression in pancreatic cancer cell lines in vitro. EUS-FNA was performed in 10 pancreatic tumors. After topical application of the probe, signal intensity was measured using a fluorescence imaging system for 13 min. GGT was expressed in Panc-1, AsPC-1, and AR42J, but not in KP4 cells. In samples from six cases, several regions of the specimens fluoresced and contained adequate tissue for pathological diagnosis. The remaining four non-fluorescent samples contained very small amounts of carcinoma, normal epithelial cells, or no epithelial cells. The signal intensity at 5 min was 25.5 +/- 7.7 and 7.7 +/- 0.5 in fluorescent and non-fluorescent regions, respectively (p < 0.05). Application of enzymatically activatable probe onto EUS-FNA samples would be feasible for the rapid evaluation of tissues suitable for histological diagnosis.