Development of a laser speckle imaging system for measuring relative blood flow velocity

Abstract

Determining the viability of damaged or surgically reconstructed tissue is critical in most plastic and reconstructive surgery procedures. Information about tissue blood flow in the region in question can make this determination much easier. Laser speckle imaging (LSI) is one technique that could potentially aid in making this determination. LSI is a non-contact full-field imaging technique with simultaneous high spatial and temporal resolution. Tissue is illuminated with diffuse red laser light and the spatial and/or temporal statistics of the resulting speckle pattern can be used to calculate relative flow velocities. We have developed a LSI system that produces relative velocity blood flow images. Bench tests of the system indicate that it may be used to distinguish between normal, decreased, and increased blood flow states of a human finger. The system has also been used to take some initial laboratory measurements using an animal model - an epigastric free flap on a rat. Preliminary results indicate that the method may be used to distinguish states of venous or arterial occlusion from unoccluded states of the skin flap. While further experimentation is necessary, these initial results indicate that LSI could be a useful aid to the plastic surgeon for assessing tissue viability.