The Positioning Research Of Apparent Diffusion Coefficient(ADC Value)and Fractional Anisotropy(FA Value)in Spinal Cord Injury Range Of Tethered Cord Syndrome

IntroductionThe tethered cord syndrome is a series of neurological disorders caused by innate or acquired factors of conus medullaris position up obstacles.Its main clinical manifestations including lower limb sensory-motor disorders,bowel and bladder dysfunction syndrome and other neurological damage based.Currently the tethered cord syndrome diagnosis method is conventional MRI scan,but conventional MRI can only determine whether low conus,the degree and rank of damage to the spinal cord can not accurately determined.This study investigate the accuracy and feasibility to judgment the spinal cord injury range through apparent diffusion coefficient(ADC value)and fractional anisotropy(FA value)in tethered cord syndrome.SECTION ONE: Optimization of the scan parameter for MRI diffusion tensor imaging of the thoracolumbar spinal cordObjective:Explore the influence of different diffusion tensor imaging(DTI)scan parameters to the image quality to obtain the optimal thoracolumbar spinal cord scan sparameters.Metheds:30 normal adult healthy volunteers were randomly divided into 3 groups,:the b values group,the diffusion gradient directions group and the thickness / layer spacing group.Scanning the thoracolumbar spinal cord by DTI and measuring the FA value and ADC value of the four segments above the spinal conus.Results:When the number of diffusion gradient directions is 32,its average result is 2.6 ± 0.323,and it had a statistically significant difference(P <0.05)compared with 15(2.2 ± 0.426)and 6(1.6± 0.316).When the b value was 800 s / mm2,its average result is 2.7 ± 0.357.It had no statistic differences compared with 1000 s / mm2(2.6 ± 0.320).When the b value is 600 s / mm2,the average result was 2.0± 0.499,compared with the other two groups,the differences were statistically significant.When the layer thickness / layer spacing is 2mm / 0 mm,the average result is 2.7 ± 0.329.When the thickness / layer spacing is 3 mm / 0 mm,the average result is 2.6 ± 0.319.When the thickness / layer spacing is 4 mm / 0 mm,the average result is 2.7 ± 0.264,the differences were not statistically significant in the 3 groups(P> 0.05).Conclusion:(1)The ADC value and FA value can be accurately obtained by setting different DTI scan parameters of thoracolumbar spinal cord,for this research and clinical application.(2)This study suggests that for lumbar spinal clinical application of diffusion tensor MRI scan optimal scanning parameters are: number of diffusion gradient directions is 32,b value is 800 s / mm2,thickness / layer spacing is 2 mm / 0 mm.SECTION TWO: The positioning research of apparent diffusion coefficient(ADC value)and fractional anisotropy(FA value)in spinal cord injury range of tethered cord syndromeObjective:Explore the feasibility of MRI diffusion tensor imaging show the tethered cord syndrome;Assess the FA value and ADC value differences,in order to determine the tethered cord syndrome spinal cord injury range.Methods:This study including 15 healthy volunteers and 15 patients with urinary incontinence.All examinations were using Philips Achieva 3.0T TX MRI dual-source scanner,gradient field strength of 80 m T / m,gradient field switching rate of 200 T / m / s.Coil selection Philips 16 Channel Torso XL coil.Scanning all the people's four segments above the conus and measuring the average FA values and ADC values at the FA and ADC maps.Results:(1)All the FA values and ADC values can be measured from the DTI in healthy volunteers and patients.(2)The average ADC value is 1.244± 0.061 on the all segments of the control group,compared to the experimental group(1.052±0.045),the difference was statistically significant(p <0.05).The average FA value is 0.866±0.030 on the all segments of the control group,compared to the experimental group(1.079+0.049),the difference was statistically significant(p <0.05).(3)Compare each segment separately,the experimental group conical section IV FA value is 0.480 ± 0.002,compared to the control group(0.563 ± 0.041),the difference was statistically significant(p <0.05).Conclusion:(1)DTI can accurately quantify the spinal cord injury of tethered cord syndrome by measuring the FA values and ADC values.(2)The tethered cord syndrome patients who showed by urodynamic barriers with spinal cord injury,the damage range mainly in the fourth segment above the conus.(3)This study suggest that urinary incontinence symptoms in patients with tethered cord syndrome is associated with the injury thoracolumbar hypogastric nerve,according to the results of DTI,combined with the innervation of the bladder and urine flow mechanics test.