Quantitative assessment of changes in skeletal muscle injury by computer-aided analysis based on two-dimensional ultrasonography combined with contrast-enhanced ultrasonography and estimated by a modified semi-quantitative scoring system: An experimental study in a contusion model

The aim of this study was to investigate the potential application of computer-aided analysis in the quantitative assessment of changes in skeletal muscle injury in the rabbit contusion model. Forty healthy rabbits were randomly divided into control (n = 5) and contusion (n = 35) groups. Rabbits in the contusion group were used to construct a muscle contusion model induced by a hammer hitting the right gastrocnemius, while the muscles of rabbits in the control group were non-injured. Two-dimensional ultrasound (2D US) and contrast-enhanced ultrasonography (CEUS) were performed on the rabbits that had received skeletal muscle contusion injury at 1 h, and 1, 3, 7, 14, 21 and 28 days after injury. Afterwards, a multiscale blob feature (MBF) method was used to extract the textural features from the 2D US, and the muscle injuries were quantitatively evaluated. The eight textural parameters of skeletal muscle analysed by MBF at 1 h, and 1, 3 and 7 days post-injury were found to be significantly higher in the contusion group than in the control group (p < .05). On Day 14, the textural parameters (e.g., greyscale mean [Mean], greyscale standard deviation [SDev], number of blobs, average size of blobs, homogeneity of distribution, periodicity of distribution [POD] and irregularity) were also evidently higher in the contusion group than in the control group (p < .05). On Day 28, Mean, SDev and POD in the contusion group were markedly higher (p < .05). After that, the microcirculation in the injured areas increased from Day 7 to Day 21 after injury, but decreased on Day 28 after injury. Thus the quantitative assessment of changes in skeletal muscle injury (SMI) using computer-aided analysis allowed us to describe the geometric features of injured muscle fibres and the microperfusion changes estimated by the modified semi-quantitative scoring system. This provides a scientific basis for the development of a novel approach for the evaluation of SMI and rehabilitation process.