DTIand DTT Of Lumbar Nerve Roots: The Preliminary Results

Objectives: The purpose of this preliminary study were to demonstrate thefeasibility of diffusion tensor imaging （DTI） and tractography in human lumbar nerveroots, and to assess potential differences in the DTI parameters of the lumbar nervesbetween healthy volunteers and patients suffering from disc herniation.Materials and Methods:20disc herniation patients were performed withunilateral sciatica （11cases of left,9cases of right）,20volunteers were choosed ascontrol group. GE Signa HDxt3.0T superconducting magnetic resonance machine withspinal8channel phased-arrayed coil were employed for all the patients and volunteers.The same FOV, slice thickness, gap and slice number as for the axial T2-weightedsequence images were used in order to allow the anatomical correlation. Transfered allthe images to workstation and tracked the patients and volunteers’ lumbar nerve rootswith FUNCTOOL4.3software,fustioning with the T2WI image as a anatomicbackground, observe compressed nerve roots and the contralateral nerve roots inpatients after fibre tracking, and observe both sides of lumbar nerve roots in volunteersafter DTT performed. DTI post-processing software application generated color codingFA and ADC maps, measuring the FA value and ADC values of compression nerve rootand the corresponding level of contralateral side; Corresponding to the same areameasurement volunteers bilateral nerve root of the FA value and ADC values thanks forthe T2WI image fusion as anatomical background; Statistical software SPSS17.0wasused. P values inferior to0.05were considered statistically significant,Because of thesmall sample size of patients, statistical analysis was performed with t test.Results:1.group of patients:（1）T2EPI shows the signal of the pressure areas lower than the corresponding regional of contralateral and volunteers’ nerve roots, there is part of the form, and shiftchange such as flat; Color coded FA map showed mainly blue and green color-codepixels; Color coded pixels ADC map showed mainly blue and green.（2）Fiber tracer imaging: Combined with T2WI image as anatomical background,transforming T2WI level to observe visually in3D of the pressurized side nerve rootwith migration, bending, sparse change.（3）DTI parameters: The mean FA value of compression nerve roots is0.197±0.032, ADC values is(1.48±0.13×10^-3mm²/s; The mean of FA value is0.351±0.044, ADC values is（1.32±0.14）, the mean FA values were statistically lowerin the compressed nerve root than in the contralateral nerve root and the lumbar nerveroots of the volunteers. ADC values were significantly higher in the compressed nerveroot than in the contralateral nerve root and the lumbar nerve roots of volunteers.2. Group of volunteers:（1）DTI performance: T2-EPI showed the section of lumbar backbone is round,oval, or triangle, compare to the soft tissue around is obviously high signal; Color codedFA map showed mainly red color-code pixels with some yellow and green around;Color coded pixels ADC map showed mainly blue and green.（2）Fiber tracking: Combined with T2WI image as anatomical background,transforming T2WI level to observe visually in3D of the pressurized side nerve rootwithout sparse, interruption, migration.（3）DTI parameters: the mean FA value of volunteers left nerve root is0.319±0.059,ADC values is （1.38±0.27）×10^-3mm²/s; The mean FA value of right nerve rootis0.326±0.046, ADC values is （1.39±0.28）×10^-3mm²/s was the/s; The mean FA valueof Volunteers L5nerve root is0.332±0.068, ADC values is （1.29±0.19）×10^-3mm²/s,the mean FA value of S1nerve root is0.312±0.060, ADC values is （1.47±0.22）×10^-3mm²/s, there was no significant difference in FA or ADC between left and right nerveroots at the same level, and between L5and S1roots （p>0.05）.Conclusion:1.DTI and DTT of healthy volunteers and patients suffering from disc herniationperformance:（1） T2-EPI: all hyper intense;（2） Color coded FA map: red color reducein compression nerve roots;（3） Color coded ADC map: yellow, green color increase incompression nerve roots levels;（4） Fiber tracking: As T2WI image for anatomicalbackground, never roots observed in3d directly.2.In healthy volunteers, there was no significant difference in FA or ADC between left and right nerve roots at the same level, and between L5and S1roots （p>0.05）.3.In patients, the mean FA values were statistically lower in the compressednerve root than in the contralateral nerve root and the lumbar nerve roots of thevolunteers. ADC values were significantly higher in the compressed nerve root than inthe contralateral nerve root and the lumbar nerve roots of volunteers.