Monitoring free tissue transfer using laser speckle imaging

摘要

Blood velocity information can be extracted by analyzing, either temporally or spatially, laser speckle (LS) patterns generated when a laser source illuminates the tissue. While a temporal analysis, such as that used for laser Doppler velocimetry (LDV), provides high spatial resolution, the time required to obtain flow data in vivo on large areas of tissue limits its utility. The LS imaging (LSI) technique combines the nonscanning, full-field, LS method and the modified multiple scattering algorithms developed for LDV analysis to retrieve blood velocity parameters. It provides a noninvasive means for realtime, quantitative measurements of subtle changes in the tissue vasculature. This paper describes the use of the LSI technique on free flap measurements of a swine model and compares the results with those obtained using an LDV probe. Both the LSI and the LDV measurements showed similar results - blood velocity and flow decreased about 10%-33% from the tip to the caudal base of the flap, respectively. The difference between the tip and the caudal base is a measure of flap ischemia. However, tissue pigmentation affects the blood flow parameters retrieved from the LDV measurements, it does not affect the blood velocity parameters retrieved from the LSI measurements. Both techniques were also used during free tissue transfer procedures in patients to demonstrate the utility of the LSI for monitoring the status of the graft.