Diffusion Tensor MRI-Based Dynamic Study Of Acute Injury And Frozen Recovery In Rat Skeletal Muscle

ObjectiveTo evaluate the application value in mice skeletal muscle after acute injury and rehabilitation effect with different frozen time by DT-MRI.Methods and materials28 weistar mice(female,387.96g±37.14g) were randomized into 4 groups(one control group,three experimental groups).The skeletal muscle trauma models were made in left leg muscle by Microcomputer-controlled electronic pressure instrument (Pressure was 500N,Velocity was 100mm/min).Among them,control group did not give any interference after injury.Experimental groups were given ice compress immediately after injury 5 minutes,15 minutes and 30 minutes.DTI(Philips Intera Achieva 3.0T MRI) was performed before the injury,immediately after the injury,24 hours,48 hours and 72 hours.Scan parameters:TR/TE=1857/65ms,b=600 s/mm²,six diffusion probing gradient directions,5mm thickness and zero spacing.ADC and FA values were calculated by fiber tracking tool.The morphological change of mice skeletal muscle was assessed by HE staining and immunohistochemical method of Desmin and HSP70.Results(1) ADC and FA values were 1.36±0.08 x 10-³mm²/s and 0.46±0.05 and had no statistical differences in each group before the injury.(2) ADC values were increased to 1.86±0.12 and 1.54±0.15×10^-3mm²/s,and FA values were decreased to 0.21±0.04 and 0.25±0.04 for controls in immediately after the injury and 24 hours.(3)ADC values were respectively 1.79±0.10,1.55±0.09 and 1.57±0.08x10-3mm2/s, and FA values were respectively 0.26±0.03,0.314±0.06 and 0.30±0.04 at the 5,15 and 30 minutes groups in immediately after injury.ADC values were respectively 1.57±0.13,1.42±0.06 and 1.48±0.08x10-3mm2/s,and FA values were respectively 0.26±0.02,0.37±0.03 and 0.35±0.05 in the three experimental groups in 24 hours after injury.So the control group and 5 minutes group were no statistical differences and the range of change in the ADC and FA values were reduced in 15 and 30 minutes groups.(4) The ADC and FA values had no significant difference between the control and experimental groups in 48 and 72 hours.(5) The disorder arrangement of skeletal muscle cells with edema and filaments separate were found in HE staining after injury,but the degree mitigated in 15 and 30 minutes groups.Desmin staining changed thinningz and fuzzy edge in immediately after the injury and 24 hours,and increased in staining after 48 hours.HSP70 staining were high-level expression in each times after injury.ConclusionsDTI can non-invasively reflect the recovery process after acute injury of muscle. Using appropriate ice compress time could mitigate edema of skeletal muscle.