ERBB2 and head and neck squamous cell carcinoma: Because the FAD fluorescence signal is weaker than NAD(P)H in tissue and two channel metabolic imaging significantly increases time and cost,18,19 in this study, we used fluorescence lifetime imaging microscopy (FLIM) of NAD(P)H alone to specifically investigate the impact of the HER2 on two human HNSCC cultures, SCC74A and SCC74B, expressing low and high HER2, respectively.20