Acute Neck Trauma Of MR Diffusion Tensor Imaging

Background and ObjectiveCervical spine trauma has become a common clinical emergency, severe cases can cause paralysis and even death. Therefore, early rapid and accurate assessment of the severity and scope is valuable for formulating appropriate treatment schedule and reducing secondary impairment caused by delayed treatment. In recent years, diffusion tensor imaging (DTI) and fiber tracer (FT) technology are used in clinic more widely, which is the only non-invasive organism imaging methods quantify the diffusion size and orientation of water molecule in tissues, so as to show the intact of white matter tracts and detect subtle change of spinal cord. This study is designed to investigate the change of the values of ADC and FA in posterior limb of internal capsule and cervical spinal cord, and explore the value of DTI and FT in the evaluation of acute spinal cord injury.Materials and MethodsTwenty-eight patients with acute neck trauma (injury time<3d) were collected in our hospital from September 2014 to October 2015, contained traffic accident 13 cases, fall injury from high space 9 cases, crash or fall injury 6 cases. All patients underwent routine MR imaging and DTI of head and neck. Spinal cord function were evaluated according to muscle strength, muscle tone, feel and function stool, and divided into three degrees of spinal cord injury:mild, moderate and severe. The patients were divided into two groups according to spinal cord signal on T2WI:A group with high signal and B group with normal signal. Thirty five matched healthy volunteers were collected as control. DTI of brain and cervical spinal cord was acquired with SE-EPI sequence, and b value was 1000s/mm2. ROI was placed in bilateral posterior limb of internal capsule and cervical spinal cord with high signal on T2WI or maximum compression segment. The DTI data were post-processed with Functool software, to get the spinal cord fiber bundles images, ADC and FA artifact color images of head and spinal cord. The values of ADC and FA were measured and compared. Using SPSS16.0 statistical software for statistical analysis, quantitative data were expressed as mean ± standard deviation (x±s) that the groups comparison of measurement data used ANOVA; comparison between groups used Q test (Newlnan-keuls Test), and P<0.05 was considered statistically significant.ResultTwenty eight cases of patients with acute traumatic cervical spinal cord injury had varying degrees of symptoms; there were varying degrees change of limb muscle strength and muscle tone in 28 cases, sensation change in 19 cases, sphincter disorder in 7 cases. According to clinical classification,13 cases were mild cervical spinal cord injury,9 cases were moderate spinal cord injury,6 cases were severe spinal cord injury. The brain of all patients and healthy controls were normal on conventional MR imaging. Seventeen patients had cervical spinal cord high signal on T2WI and brought into A group,11 cases with normal signal were included in B group.The ADC values of mild, moderate and severe spinal cord injury groups were (0.91 ± 0.05)× 10-3mm2/s, (0.99 ± 0.24) × 10-3mm2/s and (1.3± 0.03)× 10-3mm2/s, respectively, the difference was statistically significant among three groups (F= 11.36, P= 0.0011). The FA values of three groups were (0.52±0.04), (0.46±0.07) and (0.39±0.03), respectively, the difference was statistically significant among three groups (F= 9.67, P= 0.0058). The ADC values had no statistical difference between three groups and controls (F= 3.83, P= 0.0526]. The FA value was lower in sever spinal cord injury group than that in control (F= 7.67, P= 0.0301).The ADC values in group A, group B and control were (1.20+0.27) X 10-3mm2/s, (0.95±0.20) ×10-3mm2/s and (0.80±0.20) X 10-3mm2/s, there are significant differences among groups (F= 9.85, P= 0.0023). The FA values in group A, group B and control were (0.41±0.07), (0.50±0.07) and (0.66±0.09), the difference was statistically significant (F= 9.59, P= 0.0061) among groups.The fiber bundle structure was acceptable, without significant decrease and course change in mild cervical spinal cord injury patients; which showed decrease significantly with integrity reducing and fuzzy structure in moderate cervical spinal cord injury patients; and displayed tow scarce with destruction interrupted in severe cervical spinal cord injury patients. The cervical fiber bundle displayed sparse, shift and part twisted fracture in group A, which showed part of the sparse change without significant shift and distortion fracture in group B. The fiber bundle was full with clear structure and running naturally in control.ConclusionDTI is more sensitive than conventional MRI scans for spinal cord injuries, can detect occult spinal cord injury that can not be displayed with conventional MR imaging. The ADC and FA values of cervical spinal cord are different in three degrees injury. The FA values of bilateral posterior limb of internal capsule decreases in severe cervical spinal cord injury. FT can directly observe fiber bundle sparse, twisted, fracture and displacement.