Real-time intraoperative fluorescence lifetime imaging of 5-ALA induced PpIX and autofluorescence in brain tumors: first results in patients

5-ALA induced PpIX is increasingly used for guiding brain tumor resection surgery. The current intensity-based approach fails at detecting lower concentrations of PpIX found in low-grade gliomas or the infiltrative edge of glioblastomas. Here, we report the first results in patients of real-time, PpIX fluorescence lifetime measurements using a hand-held fiber probe. Fluorescence from different spectral channels (390/40 nm (Collagen), 470/28 nm (NADH), 629/53 nm (PPIX)), is augmented onto a video stream of the surgical field-of-view to provide intraoperative tumor visualization in real-time. In-vivo data reveals strong contrast between regions of high PpIX accumulation associated with tumor (>8 ns) and healthy brain tissue (<4 ns).