Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; Department of Neurology, The Walton Centre NHS Foundation Trust, Liverpool, United Kingdom.
Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; Royal Society, London, United Kingdom.
Neuroimage Clin. 2019;24:102024. doi: 10.1016/j.nicl.2019.102024. Epub 2019 Oct 17.
To investigate the agreement between manually and automatically generated tracts from diffusion tensor imaging (DTI) in patients with temporal lobe epilepsy (TLE). Whole and along-the-tract diffusivity metrics and correlations with patient clinical characteristics were analyzed with respect to tractography approach.
We recruited 40 healthy controls and 24 patients with TLE who underwent conventional T1-weighted imaging and 60-direction DTI. An automated (Automated Fiber Quantification, AFQ) and manual (TrackVis) deterministic tractography approach was used to identify the uncinate fasciculus (UF) and parahippocampal white matter bundle (PHWM). Tract diffusion scalar metrics were analyzed with respect to agreement across automated and manual approaches (Dice Coefficient and Spearman correlations), to side of onset of epilepsy and patient clinical characteristics, including duration of epilepsy, age of onset and presence of hippocampal sclerosis.
Across approaches the analysis of tract morphology similarity revealed Dice coefficients at moderate to good agreement (0.54 - 0.6) and significant correlations between diffusion values (Spearman's Rho=0.4-0.9). However, within bilateral PHWM, AFQ yielded significantly lower FA (left: Z = 4.4, p<0.001; right: Z = 5.1, p<0.001) and higher MD values (left: Z=-4.7, p<0.001; right: Z=-3.7, p<0.001) compared to the manual approach. Whole tract DTI metrics determined using AFQ were significantly correlated with patient characteristics, including age of epilepsy onset in FA (R = 0.6, p = 0.02) and MD of the ipsilateral PHWM (R=-0.6, p = 0.02), while duration of epilepsy corrected for age correlated with MD in ipsilateral PHWM (R = 0.7, p<0.01). Correlations between clinical metrics and diffusion values extracted using the manual whole tract technique did not survive correction for multiple comparisons. Both manual and automated along-the-tract analyses demonstrated significant correlations with patient clinical characteristics such as age of onset and epilepsy duration. The strongest and most widespread localized ipsi- and contralateral diffusivity alterations were observed in patients with left TLE and patients with HS compared to controls, while patients with right TLE and patients without HS did not show these strong effects.
Manual and AFQ tractography approaches revealed significant correlations in the reconstruction of tract morphology and extracted whole and along-tract diffusivity values. However, as non-identical methods they differed in the respective yield of significant results across clinical correlations and group-wise statistics. Given the absence of excellent agreement between manual and AFQ techniques as demonstrated in the present study, caution should be considered when using AFQ particularly when used without reference to benchmark manual measures.
探讨在颞叶癫痫（TLE）患者中，从弥散张量成像（DTI）手动和自动生成束的一致性。针对轨迹追踪方法，分析了整体和沿束弥散性指标与患者临床特征的相关性。
我们招募了 40 名健康对照者和 24 名 TLE 患者，他们接受了常规 T1 加权成像和 60 个方向的 DTI。使用自动（自动纤维定量，AFQ）和手动（TrackVis）确定性追踪方法来识别钩束（UF）和海马旁白质束（PHWM）。针对自动和手动方法之间的一致性，分析了束扩散标量指标（Dice 系数和 Spearman 相关性），以及癫痫起始侧和患者临床特征，包括癫痫持续时间、癫痫起始年龄和海马硬化的存在。
在两种方法中，束形态相似性分析均显示出中等至较好的 Dice 系数（0.54-0.6），并且扩散值之间存在显著相关性（Spearman 的 Rho=0.4-0.9）。然而，在双侧 PHWM 内，AFQ 生成的 FA 值显著降低（左：Z=4.4，p<0.001；右：Z=5.1，p<0.001），MD 值升高（左：Z=-4.7，p<0.001；右：Z=-3.7，p<0.001），与手动方法相比。使用 AFQ 确定的整个束 DTI 指标与患者特征显著相关，包括 FA 中的癫痫起始年龄（R=0.6，p=0.02）和同侧 PHWM 的 MD（R=-0.6，p=0.02），而校正年龄后的癫痫持续时间与同侧 PHWM 的 MD 相关（R=0.7，p<0.01）。使用手动全束技术提取的临床指标与扩散值之间的相关性在进行多次比较校正后不再显著。手动和自动沿束分析均显示出与患者临床特征的显著相关性，例如起始年龄和癫痫持续时间。与对照组相比，左侧 TLE 患者和海马硬化患者表现出最强和最广泛的同侧和对侧弥散性改变，而右侧 TLE 患者和无海马硬化患者则未表现出这些强烈影响。
手动和 AFQ 束追踪方法在束形态重建和提取的整体及沿束弥散性值方面显示出显著的相关性。然而，由于它们是不同的方法，在各自产生与临床相关性和组间统计的显著结果方面存在差异。鉴于在本研究中手动和 AFQ 技术之间没有显示出优异的一致性，因此在使用 AFQ 时应谨慎，特别是在没有参考基准手动测量值的情况下使用时。
