Time course of diffusion tensor imaging metrics in the chronic spinal cord compression rat model

Background Diffusion tensor imaging (DTI) provides information about water molecule diffusion in spinal cord. Purpose This study was aimed to investigate DTI changes in the different stages of compressive spinal cord induced by water-absorbing material implantation. Material and Methods The spinal cord compression was administered over the fourth cervical vertebral level in rat. Rat models were divided into five subgroups according to compression stages: sham group, group A: three-day compression rat models; group B: 12-day compression rat models; group C: 20-day compression rat models; group D: 60-day compression rat models. DTI including fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in the compressive spinal cord were collected. The relationship between the Basso, Beattie, and Bresnahan (BBB) scores and DTI metrics was further explored. Results Compared with the sham group, BBB scoring of rat model showed a decreased tendency from group A (P < 0.05) to group B (P < 0.05). Then the motor function of rat model hindlimbs was recovered in some degree from group C (P < 0.05) to group D (P < 0.05) but had significant motor defects when compared with the normal level (P < 0.05). The DTI metrics results revealed that chronic spinal cord compression resulted in lower FA value and higher ADC value at the compressive spinal cord level assessed at all four time-points (P < 0.05). DTI metrics also showed a close correlation with motor function (P < 0.05). Conclusion DTI is an optimal pre-clinical imaging tool to reflect locomotor performance and pathological status of compressive spinal cord epicenter in chronic spinal cord compression rat model.