Objective To distinguish the edema

injury

or rupture in the traumatic skeletal muscle fiber in vivo using diffusion tensor imaging （DTI） and tractography on magnetic resonance imaging （MRI）. Methods The skeletal muscle trauma models were made in 4 rabbits （eight hindlimbs） by iron discus （weight 1.0 kg

diameter 6 cm） falling down vertically from 45 cm height to rabbits’ thighs. Conventional sequences and two-dimensional （2D） diffusion-weighted （DW） spin-echo （SE） echo planar imaging （EPI） sequence with fat suppression （b=600 s/mm

2

） were performed on 1.5T MRI scanner. The grading of edema

injury

and fiber rupture in the damaged muscle were made according to their histopathological views

which was consistent with the images. The mean apparent diffusion coefficient （ADC） values and fractional anisotropy （FA） values were measured from the region of interests （ROIs） of all groups on 2D DW images used for tractography. Analysis of variance test was performed to analyze all data. Results ADC values of the areas in normal muscle

edema muscle

injury muscle

and ruptured muscle were （6.12±1.34）×10

-3

（6.38±1.30）×10

-3

（8.06±0.97）×10

-3

and （9.57±0.93）×10

-3 mm

2 /s

respectively. There was significant difference among groups （P

<

0.001）

but no difference between edema muscle and normal muscle group （P

>

0.05）. The FA values of normal muscle

edema muscle

injury muscle

and ruptured muscle were 0.42±0.12

0.36±0.12

0.26±0.09

0.12±0.08

respectively

with a significant difference among groups （P

<

0.001）. In the edema muscle

the tracking cross-fiber could be seen but it decreased slightly. In the injury muscle

the tracking fiber decreased markedly. In the ruptured muscle

the transverse-orientation tracking fiber vanished

yet some interrupted longitudinal-orientation tracking fiber could be found. Conclusion The edema

injury

and rupture of muscle fiber in rabbit damaged skeletal muscle can be verified according to the ADC and the FA on DTI and tractography.