Structural and functional tissue analysis under skin using near infrared spectral imaging

The infrared imaging technique will become a typical noninvasive measurement method in clinical medicine. However, the pathophysiological meaning of infrared imaging has not been analyzed schematically. The authors have developed an infrared imaging system, which can detect spectroscopic images from near infrared images to far infrared thermography. Near infrared images are taken by a cooled charge-couple-device (cooled CCD) applying an active light source such as a halogen light and laser diodes in reflecting and transparent mode. Middle infrared images are measured by an infrared camera, which can detect short wavelengths less than 3.0 microns. Far infrared images are taken by a dynamic thermographic instrument to measure radiated rays. Using projected infrared rays of 880 nm, the vascular network in subcutaneous tissue has been observed in transparent and reflective mode. Using infrared rays of 760 nm and 800 nm, blood volume and oxygenation images of subcutaneous tissue have been obtained in dynamic mode. A near infrared image of subcutaneous tissue combined with a thermal image of skin surface which was simultaneously taken by an image overlapping method, and the pathophysiological function of cutaneous tissue was analyzed