Laser Doppler perfusion imaging (LDI) is currently used in a variety of clinical applications, however, LDI instruments produce images of low resolution and have long scan times. A new optical perfusion imager using a laser speckle measurement technique and its use for in vivo blood flow measurements are described. Measurements of human skin and surgically exposed rabbit tissue made using this instrument were compared with a commercial laser Doppler perfusion imaging instrument. Results from blood flow measurements showed that the laser speckle imager measured an 11-67% decrease in blood flow under arterial occlusion. Under similar conditions, the laser Doppler imager measured blood flow decreases of 21-63%. In comparison with LDI, it was observed that the higher temporal resolution of the laser speckle imager was more sensitive to measuring the hyperaemic response immediately following occlusion. This in vivo study demonstrated some of the several advantages laser speckle imaging has over conventional LDI, making the new instrument more versatile in a clinical environment.

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Laser Doppler imaging (LDI) has become a standard method for optical measurement of tissue perfusion, but is limited by low resolution and long measurement times. We have developed an analysis technique based on a laser speckle imaging method that generates rapid, high-resolution perfusion images. We have called it laser speckle perfusion imaging (LSPI). This paper investigates LSPI output and compares it to LDI using blood flow models designed to simulate human skin at various levels of pigmentation. Results show that LSPI parameters can be chosen such that the instrumentation exhibits a similar response to changes in red blood cell concentration (0.1%-5%, 200 microL/min) and velocity (0-800 microL/min, 1% concentration) and, given its higher resolution and quicker response time, could provide a significant advantage over LDI for some applications. Differences were observed in the LDI and LSPI response to tissue optical properties. LDI perfusion values increased with increasing tissue absorption, while LSPI perfusion values showed a slight decrease. This dependence is predictable, owing to the perfusion algorithms specific to each instrument, and, if properly compensated for, should not influence each instrument's ability to measure relative changes in tissue perfusion.

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The kinetics of blood flow during excisional wound healing in the red Duroc model are comparable with that previously observed in laser Doppler imaging of healing human skin wounds and hypertrophic scars. These results therefore confirm that the red Duroc is a good model of human wound healing, and further indicates that the LSPI is an excellent technique for evaluating angiogenesis and neovascularization during healing in this and other models.