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Hyperspectral imaging, image analysis and diffusion theory were used to visualize skin vasculature and to monitor the development of fresh skin bruises. Bruises were inflicted in a porcine model, and the development of the hemorrhage was monitored using white light hyperspectral imaging (400-1000 nm). Hyperspectral images from human volunteers were also included in the study. Statistical image analysis was used to classify bruised regions and to visualize the skin vasculature. Biopsies were collected from the animals to reveal the true depth of the bruising. A three-layer diffusion model and an analytic hemoglobin transport model were used to model the reflectance spectra from the images. The results show that hyperspectral images contain depth information, and that the approximate depth and extent of bruises can be retrieved using a combination of statistical image analysis and diffusion theory. This technique also shows potential to visualize vascular structures in human skin., (2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background and Objective: Bruises are currently evaluated by visual inspection, and little is known about the first phase after injury. The temporal development of fresh injuries must be accurately described to be able to age bruises in a reliable manner. Color changes in a bruise caused by hemoglobin breakdown products will depend on the severity of the trauma, and thus on the local immune response in the skin. It is therefore important to relate the nature of the impact to the temporal tissue responses., Materials and Methods: Controlled injuries were inflicted on anesthetized domestic pigs. Trauma was induced either by a pendulum device, or by paintballs released using pressurized air. The speed of the projectiles was recorded using a high speed camera. Biopsies and reflection spectra (400-850 nm) were collected from normal and bruised skin. The experiments were approved by the national animal research authority., Results: The temporal development of the injury was found to depend strongly on the weight and speed of the object. Low speed, blunt objects did not cause persistent skin changes. However, deep muscular bleeding could be found in most cases. High speed, light weight objects caused a rapidly developing bruise. These bruises were fully developed within 15-20 minutes. No deep muscular hemorrhages were observed in those cases. White blood cells (neutrophilic granulocytes) could be found in biopsies from high speed injuries. The amount of white blood cells depended on the time between injury and collection of the biopsies., Conclusion: Further investigations utilizing a larger range of object weight and velocities are required to be able to fully classify minor traumatic injuries. Preliminary results indicate that this can be achieved by controlled experiments using a porcine model. Reflectance spectroscopy was found to be a useful tool to study immediate skin reactions to the trauma., ((c) 2007 Wiley-Liss, Inc.)