Multimodal Imaging Laboratory, University of California, San Diego, CA 92103-8756, USA.
AJNR Am J Neuroradiol. 2009 Oct;30(9):1740-7. doi: 10.3174/ajnr.A1650. Epub 2009 Jun 9.
Noninvasive imaging plays a pivotal role in lateralization of the seizure focus in presurgical patients with temporal lobe epilepsy (TLE). Our goal was to evaluate the utility of diffusion tensor imaging (DTI) tractography in TLE.
Twenty-one patients with TLE (11 right, 10 left TLE) and 21 controls were enrolled. A 1.5T MR imaging scanner was used to obtain 51 diffusion-gradient-direction images per subject. Eight pairs of white matter fiber tracts were traced, and fiber tract fractional anisotropy (FA) was calculated and compared with controls. Fiber tract FA asymmetry and discriminant function analysis were evaluated in all subjects and fiber tracts respectively.
Compared with controls, patients with TLE demonstrated decreased FA in 5 ipsilateral fiber tracts. Patients with left TLE had 6 ipsilateral and 4 contralateral fiber tracts with decreased FA. Patients with right TLE had 4 ipsilateral but no contralateral tracts with decreased FA compared with controls. Right-sided FA asymmetry was demonstrated in patients with right TLE for 5 fiber tracts, and left-sided asymmetry, for patients with left TLE for 1 fiber tract. Discriminant function analysis correctly categorized patients into left-versus-right TLE in 90% of all cases (100% correct in all patients without hippocampal sclerosis) by using uncinate fasciculus and parahippocampal fiber tracts.
We found widespread reductions in fiber tract FA in patients with TLE, which were most pronounced ipsilateral to the seizure focus. Patients with left TLE had greater, more diffuse changes, whereas patients with right TLE showed changes that were primarily ipsilateral. Disease was lateralized to a high degree independent of identifiable hippocampal pathology noted on conventional MR imaging.
非侵入性成像在颞叶癫痫（TLE）术前患者的致痫灶侧别定位中发挥着关键作用。我们的目的是评估弥散张量成像（DTI）示踪技术在 TLE 中的应用价值。
共纳入 21 例 TLE 患者（11 例右侧 TLE，10 例左侧 TLE）和 21 例对照。使用 1.5T 磁共振成像扫描仪对每位受试者获得 51 张弥散梯度方向图像。追踪 8 对脑白质纤维束，计算并比较纤维束各向异性分数（FA）。分别对所有受试者和各纤维束的纤维束 FA 不对称性和判别函数分析进行评估。
与对照组相比，TLE 患者 5 条同侧纤维束的 FA 值降低。左侧 TLE 患者的 6 条同侧纤维束和 4 条对侧纤维束的 FA 值降低，而右侧 TLE 患者同侧纤维束中只有 4 条 FA 值降低，对侧纤维束中没有 FA 值降低。右侧 TLE 患者的 5 条纤维束出现右侧 FA 不对称，左侧 TLE 患者的 1 条纤维束出现左侧 FA 不对称。使用钩束和海马旁纤维束，判别函数分析可正确地将 90%的 TLE 患者（所有无海马硬化的患者均 100%正确）分为左侧 TLE 与右侧 TLE。
我们发现 TLE 患者的纤维束 FA 值普遍降低，以与致痫灶同侧最为明显。左侧 TLE 患者的变化更广泛且更弥散，而右侧 TLE 患者的变化主要在同侧。即使在常规磁共振成像上未发现可识别的海马病变，也能高度准确地对疾病进行侧别定位。
