| ObjectiveIn this study, we evaluated extratemporal abnormalities in young patients with TLE utilizing DTI images. Meanwhile, we evaluated the involved fibers in young patients with TLE utilizing DTI fiber tracking.Materials and MethodsSubjectsFrom May to November2011, we recruited20young patients with unilateral TLE (10females; aged22.70±4.23years, range18-32years;10left/10right laterality TLE; age of epilepsy onset was11.62±6.98years, range0.5-29years; duration of epilepsy was11.08±4.70years, rang3-18years). The selection criteria for TLE patients were two of the following ones at least:①a clinical diagnosis of TLE;②epileptic activity localized to the temporal lobe by video-EEG;③no other neurological disorders. All patients had undergone EEG, AEEG and MRI scan and been diagnosed as unilateral TLE by neurologists.20controls were enrolled (10females; aged23.95±4.17years, range18-31years). The selection criteria for controls:①matched with patients on the basis on age and sex;②had no nerve system disease before and no obvious positive signs of clinical neurological examination;③had no obvious anomalous signals in convention MRI scan. All participants were right-handed, and informed consent had been obtainer from those who participate.MRI acquisitionMRI data was obtained using a3.0-T GE Signa EXCITE MR imaging scanner (General Electric, Milwaukee, USA), with an eight-phase array head coil.1. Convention MRI scanConvention MR imaging consisted of a variety of sequences including:axial and sagittal T,(TR/TE=2500/24ms), axial T2(TR/TE=5100/130ms), slice thickness=5mm, interslice spacing=1.5cm, NEX=2, matrix=320×250; oblique coronal T2FLAIR obtained perpendicular to the long axis of hippocampus (TR/TE=9000/125ms), slice thickness=5mm, interslice spacing=lmm, NEX=2, matrix=512×288. FOV=230x230mm.2. DTI scanDTI was performed in the axial and sagittal plan using signal shot diffusion-weighted echo planar imaging, with the following parameters:axial plan: TR/TE=10000/88ms, slice thickness=3mm, interslice spacing=0,25noncolinear directions with a "b" value of1000s/mm,34slices, duration of the scan=4min40s; sagittal plan:TR/TE=7000/91.5ms, slice thickness=3mm, interslice spacing=0,25noncolinear directions with a "b" value of1000s/mm,25slices, duration of the scan=3min20s.Imaging analysis1. SoftwareAll of the DTI data were processed through the Functool software of GE company’s AW4.3workstation. Firstly, all the images underwent mobile correction to eliminate the misregistration caused by participants’slight moving during scan. Secondly, choosed the plane of basal ganglia to set the threshold value, the upper limit to maximum and the lower limit just to eliminate background noise without loss of useful information. Lastly, setted ROIs and tracked fibers. 2. ROIs and evaluation indexWe obtained T2WI map(b=0), color-coded map, FA map, ADC map and three eigenvalue maps through Functool software. Our ROIs included the anterior limb of the internal capsule(AIC), the posterior limb of the internal capsule(PIC), the external capsule(EC), the head of caudate nucleus(HCN), the lenticular nucleus(LN), the thalamus(TL),the frontal lobe(FL) white matter, the occipital lobe(OL) white matter, the cingulum(CG) and the fornix(FR), the genu of the corpus callosum(GCC), the body of the corpus callosum(BCC), the splenium of the corpus callosum(SCC). The ROIs were setted on axial T2WI map(b=0) and color-coded map except the FR and FR were setted on sagittal T2WI map(b=0) and color-coded map. Five DTI parameters were used to quantitatively analyze the ROIs:FA, ADC, λ1, λ2and λ3. We choosed FA, ADC, λ∥and λ⊥as the evaluation index, λ∥=λ1,λ⊥=(λ2+λ3)/2.3. Fiber trackingWe obtained T2WI map(b=0), color-coded map and FA map through Functool software. Our ROIs included CC, CG, FR.Terminage conditions of fiber tracking were:FA<0.18, ADC>0.01, Steps<160. Therefrom, we obtained default map and FA map of fibers.Statistical analysesAll data were subjected to1-Sample Kolmogorov-Smirnov test for normality. When our data met normal distribution, we used parametric test:A Paired-Samples T Test was used to compare the bilateral DTI data of all subjects. A Independent-Sample T Test was used to compare the ipsilateral and contralateral data of patients with controls. A Pearson correlation analysis was used to examine the correlation between the onset age and duration of epilepsy, and the DTI parameters. When our data didn’t meet normal distribution, we used nonparametric test. A Wilcoxon signed rank test was used to compare the bilateral DTI data of all subjects. A Wilcoxon two-sample test was used to compare the ipsilateral and contralateral data of patients with controls. A Spearman correlation analysis was used to examine the correlation between the onset age and duration of epilepsy, and the DTI parameters. Futhermore, a partial correlation analysis was used to evaluate the correlation between the onset age (duration) of epilepsy and the parameters, after controlling for the duration(/onset age) of epilepsy. Statistical analyses were performed using SPSS version13.0. AP-value of<0.05was considered statistically significant.ResultsNormality testUsing1-Sample Kolmogorov-Smirnov test for normality, we found our data met normal distribution.Comparison between the bilateral data of all subjectsThere were no statistically significant differences between the bilateral data for the four DTI parameters in the controls. Nor were there any significant differences between the bilateral data for the four DTI parameters in the patients, with the exception of FA for the TL and CG; the ipsilateral TL and CG had decreased FA compared with the contralateral thalamus in the TLE patientsComparison between patients and controlsAs there were no significant differences between the bilateral data of the four DTI parameters in the controls, we used the mean value of the bilateral data to represent the controls. In comparison to controls, TLE patients showed:lower FA in all ROIs; higher ADC in the bilateral ECs, HCNs, TLs and FR, BCC; lower λ∥in the ipsilateral LN, bilateral AICs, TLs, FLs, OLs, CGs and FR, GCC; and higher λ⊥in all the ROIs except the contralateral PIC.Correlation between DTI parameters and onset age,duration of epilepsyUsing Pearson correlation analysis, we found a negative correlation between ADC of bilateral FLs and GCC and the epilepsy onset age; and a positive correlation between ADC of GCC and the duration of epilepsy; and a negative correlation between λ∥of ipilateral PIC and the epilepsy onset age; and a positive correlation between λ∥of ipilateral FL and the duration of epilepsy; and a negative correlation between λ⊥of bilateral FLs and the epilepsy onset age; and a negative correlation between λ⊥of contralateral AIC and the duration of epilepsy; and a positive correlation between λ⊥of GCC and the duration of epilepsy. Using partial correlation analysis, after controlling for duration of epilepsy, we found a positive correlation between FA of contralateral HCN and the epilepsy onset age; and a negative correlation between λ∥of ipilateral PIC and BCC and λ⊥of ipilateral FL and the epilepsy onset age. Nevertheless, after controlling for onset age of epilepsy, we found a positive correlation between FA of ipilateral FL and the duration of epilepsy.Fiber trackingWe had tracked CC, CG and FR through Functool software. Comparing with controls, we found that CC, CG and FR were thinner and discontinued in default map in TLE group. In FA map, we found CC, CG and FR had smaller and lighter right areas and lager and darker green areas in TLE group when compared with controls. This represented than CC, CG and FR had decreased FA in TLE group.Conclusion:1. DTI can be used to evaluated the extratemporal lobe changes in young patients with TLE noinvasively and effectively.2. There are bilateral extratemporal abnormalities in TLE patients compared with controls; however, in our study, there was no significant difference between ipsilateral and contralateral ROIs except for FA of the TL and CG, a finding which needs further investigation.3. The young patients with TLE with an younger onset age or longer duration of epilepsy have more serious extratemporal changes.4. We can track the target fibers through DTT and evaluate the integrity of the fibers. |
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