Following-up the regeneration of injured rat muscle through the average pixel intensity of ultrasound biomicroscopic images

Ultrasound biomicroscopic (UBM) images can be used, in vivo, to monitor changes within the skeletal muscle of small animals such as the changes due to degeneration and regeneration processes that are associated with variations in the image echo intensity. The present work accounted the follow-up of alterations in image brightness (echo intensity) during the regeneration process of a muscle submitted to a laceration injury. UBM images of muscles from control (left) and operated (right) legs were acquired before and after operation (immediately, 7, 14, 21 and 28 days) and the echo intensity, expressed as the mean value of image pixel values corresponding to a region-of-interest (2×2mm), calculated. Mean echo intensity for the injured region was significantly lower immediately, 7, 14 and 21 days after injury and significantly higher 28 days after, than the value for the corresponding region before operation. This pattern can be associated with modifications of the tissue during the regeneration. Thus, the average pixel intensity of UBM images has proven its applicability to monitor adaptations of skeletal muscle tissue after injury.