Preliminary Magnetic Resonance Imaging Study On The Effects Of Marathon On Human Thigh Muscles

Objective:In recent years,with the development of marathon competitions across the country,the lower limb injuries caused by the competition are becoming more and more common.Among them,skeletal muscle damage,especially the hamstring injury,is the most common injury of long-distance runners.However,conventional imaging methods do not detect changes in microscopic molecular levels of skeletal muscle damage at an early stage.Diffusion tensor imaging?DTI?,a new magnetic resonance technique,can reflect changes in cell levels and provide non-invasive and effective information for early diagnosis and treatment of skeletal muscle damage before gross anatomical changes.Therefore,this study used DTI technology to compare the diffusion tensor characteristics between the non-professional marathon runners and the healthy volunteers'thigh muscle tissue—the anisotropic fraction^[1]value and the apparent diffusion coefficient?ADC?value to detect the effect of marathon motion on the microscopic molecular level of the human thigh muscle.At the same time,DTI fiber tractography technology is used to realize 3D visualization of bilateral thigh muscles.Methods:30 male non-professional marathon runners?group A?and 20male healthy volunteers?group B?were selected to meet the inclusion criteria.All subjects underwent bilateral thigh axial T1WI,T2WI and DTI scans.After the post-processing analysis and measurement of the obtained images using the Siemens Neuro 3D DTI post-processing software,the bilateral thigh anterior compartment muscles?left and right rectus femoris,left and right vastus medialis,left and right vastus lateralis,left and right vastus intermedius?,the medial compartment muscles?left and right adductor magnus,left and right adductor longus?and the posterior compartment muscles?left and right biceps femoris long head,left and right semitendinosus,left and right semimembranosus?a total of 18 muscle DTI parameters:FA value and ADC value were obtained.Two independent sample T-tests were used to compare the differences in DTI parameters between the bilateral thigh muscles of non-professional marathon runners and healthy volunteers.Results:No significant positive signs were found on the conventional T1 and T2 weighted graphs of the bilateral thigh muscles of non-professional marathon runners.There were no statistically significant differences in age,height,weight,and body mass index?BMI?among non-professional marathon runners and healthy volunteers who did not exercise regularly.The average FA value of the thigh muscles measured by the non-professional marathon runners was?0.24±0.03?,which was significantly lower than that of the healthy subjects?0.27±0.03?.The difference was statistically significant?P<0.01?.The average ADC value was?1.74±0.10?×10^-3mm²/s,which was higher than that of group B?1.70±0.09?×10^-3mm²/s,the difference was statistically significant?P<0.05?.The FA value of the thigh muscles of the anterior compartment muscles?the rectus femoris,the vastus medialis,the vastus lateralis and the average of anterior muscles?,and the posterior compartment muscles?the long biceps femoris,semitendinosus,semimembranosus and the average of posterior muscles?are less than in the healthy subjects,the difference was statistically significant?P<0.05?.There was no statistically significant difference in the FA value?adductor magnus,adductor longus?between the medial compartment muscles.The ADC value of group A was greater than that of group B in the vastus medialis,vastus intermedius and the long biceps femoris,the difference was statistically significant?P<0.05?.Conclusions:In the absence of a positive finding in conventional magnetic resonance imaging,DTI technology can non-invasively assess the subtle changes in the bilateral thigh muscles of non-professional marathon runners early in the microscopic molecular level,providing an important imaging evidence for the early changes of skeletal muscle caused by marathon.