FOLR1 and pituitary gland adenoma: –24 Using OTL38, a fluorescent folate analog, and a commercially available NIR fluorescence endoscope improved the true-positive and true-negative rates for detecting pituitary adenoma in margin specimens from 80% and 89% using white light alone to 86% and 89%, respectively, but many adenomas did not overexpress FRα (no functioning adenomas and half of the non-functioning adenomas overexpressed FRα), which remains a significant limitation.14