Deeper Tissue Imaging with Total Detection

摘要

If you simply held your finger in front of a strong source of light, you would see that visible light passes through centimeters of the tissue held in front of it. Even more light passes through tissue at near-infrared wavelengths, but even if you could see it, you would still not be able to distinguish between the bone and flesh, or other internal structures. The reason is that light scatters multiple times in the tissue, and the image blurs; resolution and contrast decrease as we try to look deeper into tissue. Other instrumental methods-such as x-ray tomography, ultrasound, and magnetic resonance imaging (MRI)-can "see through" nontransparent objects and have been revolutionary in medicine and material science, yet we are still unable to use visible light and its accompanying spec-troscopic information to look inside tissues. Recently, Combs et al. (1, 2) found a way to improve the amount of fluorescent light collected from highly scattering samples, thereby increasing the sharpness of images at depth that was never reached before. By constructing a light collector all around the surface being imaged, they increased the depth from which images could be obtained by about a factor of 2.