The Study Of The Diffusion Tensor Imaging In Patients With Trigeminal Neuralgia

ObjectiveUsing diffusion tensor imaging(DTI) sequence in a3-T magnetic resonance imaging (MRI) scanner, we measured the fraction of anisotropy (FA) and the apparent diffusion coefficient (ADC) in cisternal segment of bilateral trigeminal nerves(TGN) of the control subjects,the vascular compression point of the responsible vessel in the trigeminal neuralgia(TN) groups and the comparing the difference of ADC and FA values in three groups. We also study if there is a correlation between the change of ADC valus and the change of FA values.Besides,we measure the cross-sectional area(CSA) of vascular compression point of the responsible vessel and the corresponding point of the unaffected side in TN groups,and we also study if there is a correlation between the change of CSA and the change of ADC and FA values.To get known of the correlation between the corresponding parameters and TN by measuring the FA value、ADC value and the CSA,trying to establish a noninvasive way to diagnose the microstucture change in pathology.Materials and Methods1. Subjects1.1Normal group40healthy volunteers(who had agreed and signed the informd consent before the examination)underwent the DTI examination,and they all have no clinical symptoms associated with TN.20cases were male,and20cases were female;age range,20to83years old;mean age.51.2years old.1.2TN group40cases of TN confirmed by the neurosurgery department of our hospital were collected from September2012to December2013.16cases were male,24cases were females;age range,21-74years old;mean age,53.3years old.The course of disease from3years to20years,mean5.7years;all of the TN patients were unilateral facial pain,21cases were left,19right. TN groups were devided into ipsilateral TN groups and the contralateral TN groups2. Equipment and MethodsUsing PHILIPS Achieve3.0T MR scanner,and images were obtained using a dedicated8-channel head coil,and the scanning sequences are:①Routine sequences of control subjects and the TN group:transverse T2WI (TR/TE=3300ms/100ms)、 T1WI(TR/TE=550ms/15ms) and T2FLAIR.(TR/TE=6000ms/120ms)②Morphological sequences of TN group:3D-FIESTA (TR=5.0ms, TE=1.9ms); A plain and contrast enhancement3D-TOF-MRA (TR=16.0ms.TE=3.5ms)③T1WI-3D-TFEsequence (TR/TE=7.5ms/3.5ms) and DTI (TR/TE=7687ms×76.6ms) sequence of control subjects and the TN group.3. Cases of group and image analysisAll of the data was measured in the EWS(Extended MRWorkSpace) workstation applicates Fibertrack and Diffusion software for post-processing.Region of interest(ROI) was circular or point,ADC and Fa values were recorded seperately.In TN group,the CSA of the TGN in both sides were measured.3.1Normal groupOn the combination picture of FA color map and the T1WI-3D-TFE anatomy image.we mesure the starting point of the TGN,the1/3of the cisternal segment, the2/3of the cisternal segment,and the terminal point of the TGN to get the ADC and FA values.Besides,the health group were divided into5groups,less than30group were7cases,30-40group were8cases,40-50group were12cases,50-60group were6cases,above60group were5cases. Comparing the ADC and FA values of four points in both sides separately. In the end,comparing any two point in the unilateral side.3.2TN groupOn the FA map and ADC map generated by Diffusion software,we measured the FA and ADC values in the vascular compression point of the TGN and the corresponding point of the unaffected side. Calculating the mean FA and DTI values in the affected nerve of TN,the unaffected nerve of TN and both nerves of control subjects,whether there were statistically significances or not.Is there a correlation between the change of FA values and the change of ADC values? Besides,comparing the CSA in the vascular compression point of bilateral sides of TGN in TN group.Is there a correlation between the change of CSA and the changeof ADCand FA values?4. Statistical analysisThe statistical analysis Was performed by SPSS18.0statistical software. Mea-surement data was expressed with x±s,values of P<0.05were considered as statist-ically significant differences.①First of all,statistics of each group had to be proceeded the normality test.If they were accorded with the normal distribution,choose t test and one-way analysis of variance(ANOVA);if not,choose the nonparametric tests.②FA and ADC values of bilateral TGN from the different distance of brain stem point in40normal cases were proceeded the pair t test;dividing them into groups by ages.then FA and ADC values of bilateral trigeminal nerves from the different distance of brain stem point were also proceeded the pair t test;in the end,DTI parameters of the adjacent distance in the cisternal segment were proceeded the one-way ANOVA,and the differences of FA and ADC values between any two point of the four different points were proformed the statistical analysis.③FA and ADC values of the TGN in the patients’ affected side(ipsilateral TN),the TGN of the patients’unaffected side(contralateral TN),and both TGNs in the normal control subjects(controls) were compared,using one-way ANOVA,comparison between any two of the three groups.If they were homoscedasticity,using the LSD-t test and the S-N-K;if not,choose the Tamhane’s test.Finally,the relationship between the loss of FA and the increase of ADC was examined using the analysis of the Linear regression,and drew the scatter diagram and the Linear regression plot.④Comparing the CSA of both affected and unaffected sides by using pair t test.In the end, Finally,the relationship between the loss of CSA and the increase of ADC/the loss of FA values was examined.Results: ①each group of data is accorded with the normal distribution.②Control subjects:The mean ADC value of bilateral TGN in the health group was (1.431±0.308)×(10-3mm2/s,left (1.493±0.341)×10-3mm2/s,right (1.369±0.258)×10-3mm2/s; the mean FA was0.423±0.057, left was0.416±0.058, and right was0.431±0.055.In the40-50group, the FA and ADC values of the2/3point in the cisternal segment had a rendering asymmetric.There’s no significant difference in the FA and ADC values between any two point in the unilateral pointl.③TN group:The FA of the ipsilateral TN(0.330±0.056)was lower compared with the contralateral TN (0.408±0.054)(t=-8.448, P<0.05) and control subjects (0.423±0.057)(t=8.432,P<0.05).the FA values had no significantly difference between the contralateral TN and controls(t=1.433,P>0.05).The ADC of ipsilateral TN (2.052±0.473)×10-3mm2/s was significantly higher (P<0.05) compared with the contralateral TN (1.541±0.266)×10-3mm2/s (t=8.830,P<0.05) and control subjects (1.431±0.308)×10-3mm2/s (t=8.432,P<0.05);the ADC values had no significantly difference between the contralateral TN and controls (t=1.433,P>0.05).There’s a negative correlation between the loss of FA and the increase of ADC (r=-0.613, P<0.001).The mean CSA in the ipsilateral TN(3.75±0.35)mm2was significantly lower (t=-27.313, P<0.001) than the contralateral TN(5.21±0.33)mm2The loss of CSA and the loss of FA/the increase of the ADC had a linear relation analized by the Linear regression.Pearson correlation coefficient showed a positive correlation(r=0.526, P<0.001) between the loss of CSA and the loss of FA,and the negative correlation (r=-0.867, P<0.001) between the loss of CSA and the increase of ADC.Conclusion:Control group:1. DTI could distinguish the cistenal segment of TGN to measure the DTI parameters.2. There’s a relationship between the age and the DTI parameters of the different point from the bilateral cisternal segment of TGN in some extent. 3. As the distance from the point of brainstem to some different levels,there’s a change of the FA and ADC values in TGN.And this change was correlated with the anatomy of the cisternal segment.TN group:1. DTI showed the FA value of affected TGN in patients was lower than the unaffected TGN of patients and both TGNs of normal people,while the ADC value was high than them.This conclusion provided the very valuable information for the diagnosis of TN.There’s a negative correlation beteween the loss of FA and the increase of ADC. This phenomenon indicated that the affected side of TGN would have demyelinated obviously caused by vascular pressure which provided very valuable information for TN diagnosis.2. The CSA of affected side was significant smaller than the unaffected side of TN group.There is a strong relationship between TN and the loss of CSA.There’s a positive correlation between the loss of CSA and the loss of FA,and a negative correlation between the loss of CSA and the increase of ADC values. This phenomenon indicated the vascular compression point had the obvious atrophy(the loss of CSA),and this change of morphology was correlated with the demyelination. The more severe the demyelinated,the more serious the atrophy of TGN.3. DTI was good for the diagnosis of neuratrophy and demyelinating changes of TN caused by NVC,which could further guide the diagnosis and treatment of TN.