Visualization of the microcirculation by laser Doppler perfusion imaging

Abstract

Over the last decade a number of emerging technologies have become available for the study of microvascular blood flow. Some of these methods traumatize the tissue and seriously disturb the microcirculation; others have practical limitations in clinical use. Methods for clinical studies of the blood flow in small vessels should therefore preferably be non-invasive, versatile and easy to use. Most of the available methods that fulfill these conditions are based on optical measurement technology e.g. videomicroscopy [Fagrell et al., 1977], photopletysmography [Challoner 1979] and laser Doppler flowmetry [Nilsson et al., 1980 a,b]. Among these methods, the fiber based laser Doppler technique is the most common. This technique makes possible continuous recording of tissue blood flow at one or several sites. Because of the large spatial variation in tissue blood flow [Braverman et al., 1990] it would, however, be preferable to record the perfusion from a larger area allowing visualization of the spatial variations in tissue blood flow. This paper describes a non-invasive and nocontact system for mapping tissue perfusion, laser Doppler perfusion imaging (LDI). In addition, some potential clinical applications are illustrated.