The scientists who developed the excitation probe (Spectropen) at Emory are working with multiple models in mice showing excitation in these tumors up to 128 hours after initial tail vein injection of Indocyanine Green (ICG), although the background from surrounding normal tissues falls off within 3 hours. The effective doses of Indocyanine Green (ICG) they use in their animals models are similar to what is commonly used in humans.