Widefield frequency-domain autofluorescence lifetime imaging for detecting breast cancer in murine xenograft tumor tissues

Significance: Early and accurate detection of breast cancer is important for effective treatment and improved patient outcomes. Aim: We demonstrate a custom widefield frequency-domain fluorescence lifetime imaging (WF-FLIM) system for label-free imaging of cancerous and noncancerous mammary tissue. Approach: A custom multispectral WF-FLIM microscope was designed and built to image the endogenous fluorophores nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) for identifying the metabolic signatures of cancerous and noncancerous tissue. The lifetime measurements of the system were validated with images of NADH and FAD solutions. WF-FLIM images were acquired for MDA-MB-231 and BT474 cells and freshly excised tissues of breast cancer xenograft tumors. Results: The WF-FLIM images of different concentrations of free and bound NADH and FAD solutions confirmed the isolation of NADH and FAD signals and different lifetime values for free and protein-bound NADH. Analysis of the WF-FLIM images of breast cancer samples revealed that the mean phase and modulation lifetimes were shorter for the metastatic MDA-MB231 tumors as compared with the nonmetastatic BT-474 tumors and noninjected control mammary tissues. Conclusions: We demonstrate the utility of widefield frequency domain FLIM to rapidly measure autofluorescence lifetime differences across cells and tissues.