The Study Of Magnetic Resonance Diffusion Tensor Imaging And Biomechanical Characteristics Of Skeletal Muscle Injury In Different Periods

Objective: using 7.0 T high field strength MRI imaging system and the universal material testing machine in rat skeletal muscle injury within 24 h,72 h,5 days,7 days,9 days,2 weekes for the damage to the muscles for dynamic DTI scan and biomechanical characteristics of the test,get the radiographic images of different time points after injury of skeletal muscle and mechanical performance,study the dynamic change characteristics of skeletal muscle injury after MRI imaging,clinical sports trauma in order to achieve high field strength MRI in diagnosis,monitoring,curative effect observation,evaluate the application of the respect such as injury to provide experimental reference and theoretical basis.Methods: 106 only 3 months,SPF female SD rats which were randomly divided into 2 groups: skeletal muscle contusion model group(P group,n = 92),blank control group(group S,n = 14),two groups of rats fed alone for a week.P group rats skeletal muscle contusion model,respectively at the end of the building with each group randomly take 14 rats in 24 h,72 h,five days,7 days,9 days,2 weekes 6 point in time the gastrocnemius of 7.0 T magnetic resonance diffusion tensor imaging in vivo dynamic scan,dynamic observation in vivo changes of skeletal muscle anatomy.In addition,eight rats were randomly selected to be executed.Histopathological techniques were used to verify the changes of muscle fiber anatomy and fine structure.At each time,7 rats were randomly selected to be executed,and some rats were selected to take skeletal muscle specimens for fixation,and the fiber structure was observed by light microscope and electron microscope.Remaining rats were randomly selected in each time point 7 only executed by universal material testing machine for different time points after the contralateral side damage and damage of the biomechanical performance of the skeletal muscle when single tensile test.After the execution of some rats,the complete damaged skeletal muscle(including the bone with attachment points in both ends)was taken,and the universal material experimental machine was used to pull and pull until the muscle was broken.The computer automatically describes the load deformation curve,automatically processes and output the maximum tensile strength and maximum tensile rate data to understand the biomechanical characteristics of various stages after skeletal muscle injury.MRI results were compared with pathology and biomechanical results.The results of MRI at the same time were correlated with the results of histopathology and biomechanics.Through interview with radiology experts,seminars,and clinical skeletal muscle injury MRI image alignment method to analyze the results of the study,the different time points after injury of skeletal muscle of high field strength MRI imaging results demerit and biomechanical characteristics of high field strength MRI in skeletal muscle injury research application and value.Results: the results showed that the ADC value increased significantly in the 24 h gastrocnastus region after the injury,and the decrease of 72 h gradually increased to the normal level.After the injury,the value of 24hT1 decreased to 72 h,and then gradually decreased,and then returned to normal level 9 days after the injury.T2 was not significantly changed after 24 h after the injury,and 72 h significantly increased,then gradually decreased,and returned to normal level after 9 days after the injury.Universal material testing machine tensile experiments show that 24 h after injury of skeletal muscle tensile strength and the maximum tensile distance significantly decreased,72 h reached the lowest,then start to rise,9 days back to normal level after the injury.Histopathological examination showed that skeletal muscle contusion was more severe at 24 h and 72 h,and 5days,7days,9days and 2weeks were in the recovery stage of skeletal muscle injury.Conclusion :(1)7.0T MRI diffusion tensor imaging can obtain high resolution images of skeletal muscle in different periods of skeletal muscle.Verified by histopathology after skeletal muscle injury in different periods of the anatomy of the muscle fibers and fine structure characteristics,magnetic resonance diffusion tensor imaging results and histopathological findings are consistent.(2)the biomechanical characteristics of skeletal muscle were detected by universal material testing machine,indicating significant changes in the maximum tensile strength and maximum stretching distance of skeletal muscle in different periods after injury.Therefore,the recovery criteria for the detection of skeletal muscle injury should include the recovery of skeletal muscle strength and toughness.(3)correlation analysis between MRI results and biomechanical results showed a high correlation between the two test results.At the same time points T1,T2 MRI imaging,ADC values,respectively,and in vitro correlation analysis of monitoring results of biomechanics,T1,T2,ADC values and the maximum tensile strength and the maximum tensile range with high correlation.