Acute crush injuries of skeletal muscle of mice with ice-compression therapy: a dynamic study with diffusion tensor imaging

Abstract

Objective To evaluate the value of ice-compression therapy in mice skeletal muscle after acute crush injuries and correlate treatment effect with different compression time by MR DTI. Methods Forty Weistar mice were randomly divided into 4 groups by random number table method: control group (A), 5 min compression time group( B), 15 min compression time group(C) and 30 min compression time group(D). Diffusion tensor imaging examinations were performed before, immediately after, 24, 48 and 72 hours after injuries. ADC and FA values were calculated by fiber tracking tool. The morphological changes were confirmed by histopathology, and immunohistochemical methods were used for the assessment of Desmin expression with mean of A value. Statistical analysis by LSD-t test and Spearman rank correlation.Results (1) For every group before injuries, ADC valueswere (1.38±0.04) ×10-3,(1.38±0.08) ×10-3, ( 1.34 ± 0. 05 ) × 10 -3, ( 1.36 ± 0. 09 ) × 10 -3 mm2/s respectively, FA value were 0. 46 ± 0. 05,0. 45 ±0. 03,0. 45 ± 0. 05,0. 48 ± 0. 04 respectively. ADC values increased significantly and FA values reduced in each group immediately after injuries compared with pre-injury values. ADC values were ( 1.84 ±0. 10) × 10-3, ( 1.79 ±0. 09) × 10-3, ( 1.55 ±0. 07) × 10-3, ( 1.57 ±0. 04) × 10 -3mm2/s respectively,FA value were 0. 21 ±0. 04, 0. 26 ±0. 03, 0. 31 ±0. 02, 0. 30 ±0. 04 respectively. ADC values were still higher and FA values lower than pre-injury values at 24 hours after injury in A, B groups. ADC values were (1.54±0.13) ×10-3, (1.57±0.13) × 10-3mm2/s, FA value were 0.25 ±0.03, 0.26±0.02. (2)DTT showed fibers distorted and the number of fiber bundles reduced, some separation and displacement in each group immediately after injury. C, D groups improved more than A, B groups over time. (3) The disorder arrangement of skeletal muscle cells with edema and filaments separation were found in HE staining after injury, but the degree mitigated in C, D groups. Desmin staining became lighter with fuzzy edge immediately and 24 hours after injury, and changed more than 72 hours after injury. (4) The correlation coefficients of ADC, FA values and A value were respectively - 0. 789 and 0. 763 ( P ＜ 0. 05 ). Conclusions DTI can non-invasively reflect the pathological changes after acute crush injuries of muscles of mice and ice compression therapy. It is a useful method to guide ice compression treatment after acute crush injuries. Key words: Muscle,skeletal; Magnetic resonance imaging