Optical coherence tomography: a novel technique for the study of tissue microcirculation.

ABSTRACT

Background: Three-dimensional (3D) observation techniques are useful for understanding organ microcirculation. Optical coherence tomography (OCT) is one of the 3-D imaging techniques and is increasingly applied for tissue microcirculatory studies. Objective: This article reviews the current and prospective usages of OCT in microcirculation. Methods: OCT is an optical technique to obtain tomographic images of highly scattering media like living tissues by means of coherence gating, whose spatial resolution is down to 10 μm. It is also capable of obtaining velocity profiles of blood flow by use of Doppler frequency shift (Doppler OCT). Results: The OCT technique has been applied for observation of microvessels in rat skin, hamster dorsal skin, rat brain etc. Small microvessels down to 20 μm have been detected with the aid of Doppler OCT. Doppler OCT also revealed that the blood flow in microvessels is a quasi-steady laminar flow. The OCT signal from the cerebral cortex was found to change following neural activation, probably reflecting the functional hyperemia. Conclusion: The OCT technique combined with Doppler OCT technique has a great potential for in vivo observation of 3-D structures of microvessels and blood flow distribution. Further OCT is expected to be a depth-dependent imaging tool for the study of brain function.