Novel methods and systems to map the structure of blood vessels and monitor the flow of blood through these vascular networks using thermal imaging techniques. To obtain high contrast thermal images of the vascular structure in tissue, there must be a temperature difference between the blood/blood vessels and surrounding tissue. If the blood and blood vessels are warmer than the surrounding tissue, the vessels will appear brighter in thermal infrared images. A temperature contrast between blood vessels and the surrounding tissue can be achieved through selective heating of the blood. Hemoglobin has major absorption peaks near 420 and 530 nm, while absorption due to water (the dominant component of soft tissue) is significantly lower at these wavelengths. Irradiation of blood and tissue at these wavelengths produces selective heating of the blood compared to the surrounding soft tissue.
