Investigation of microstructural abnormalities in white and gray matter around hippocampus with diffusion tensor imaging (DTI) in temporal lobe epilepsy (TLE)

Bao, Yixin; He, Ruqian; Qing-yuan, Zeng; Zhu, Pan; Zheng, Ran; Xu, Huiqin

doi:10.1016/j.yebeh.2017.12.002

Cited by 21 publications

(26 citation statements)

References 17 publications

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“…Diffusion tensor tractography (DTT) is a computational procedure that reconstructs major fiber bundles in 3D space based on their anisotropy properties. It is a visual and quantitative tool for presenting white matter tracts from DTI data 6,7 . White matter studies using DTI usually rely on the comparison of scalar measures that quantify the diffusion within a voxel.…”

Section: Introductionmentioning

confidence: 99%

“…The most common measures, which are based on the DTI model, are fractional anisotropy (FA), which describes the degree of anisotropy within a voxel and can be attributed to the orientation of the axon fiber, and the mean diffusivity (MD), which quantifies the magnitude of diffusion. Other relevant scalar measures include axial diffusivity (AD) and radial diffusivity (RD) which estimate the diffusion parallel and perpendicular to the principle diffusion axis 6,7 . Reduction in FA represents the disorganization of axon fiber, leading to unrestricted or isotropic diffusion.…”

Section: Introductionmentioning

confidence: 99%

“…Note that up until now, there are still no reference value ranges for DTI and DTT measures in normal, healthy people. Therefore, related studies have been performed with the comparison between the contralateral (normal) and ipsilateral (abnormal) sides, or between the normal subjects (with no neurological diseases) and the patients 6 . A hemispheric based analysis was used to compare the DTI and DTT measures of specific regions of interest from the pathologic side to the healthy side in TLE patients.…”

Section: Introductionmentioning

confidence: 99%

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Hemispheric Regional Based Analysis of Diffusion Tensor Imaging and Diffusion Tensor Tractography in Patients with Temporal Lobe Epilepsy and Correlation with Patient outcomes

Alizadeh

Kozlowski

Muller

et al. 2019

Sci Rep

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Imaging in the field of epilepsy surgery remains an essential tool in terms of its ability to identify regions where the seizure focus might present as a resectable area. However, in many instances, an obvious structural abnormality is not visualized. This has created the opportunity for new approaches and imaging innovation in the field of epilepsy, such as with Diffusion Tensor Imaging (DTI) and Diffusion Tensor Tractography (DTT). In this study, we aim to evaluate the use of DTI and DTT as a predictive model in the field of epilepsy, specifically Temporal Lobe Epilepsy (TLE), and correlate their clinical significance with respect to postsurgical outcomes. A hemispheric based analysis was used to compare the tract density, as well as DTI indices of the specific regions of interest from the pathologic hemisphere to the healthy hemisphere in TLE patients. A total of 22 patients with TLE (12 males, 10 females, 22–57 age range) underwent either a craniotomy, Anterior Temporal Lobectomy (ATL), or a less invasive method of Selective Laser Amygdalohippocampectomy (SLAH) and were imaged using 3.0 T Philips Achieva MR scanner. Of the participants, 12 underwent SLAH while 10 underwent ATL. The study was approved by the institutional review board of Thomas Jefferson University Hospital. Informed consent was obtained from all patients. All patients had a diagnosis of TLE according to standard clinical criteria. DTI images were acquired axially in the same anatomical location prescribed for the T1-weighted images. The raw data set consisting of diffusion volumes were first corrected for eddy current distortions and motion artifacts. Various DTI indices such as Fractional Anisotropy (FA), Mean Diffusivity (MD), Radial Diffusivity (RD) and Axial Diffusivity (AD) were estimated and co-registered to the brain parcellation map obtained by freesurfer. 16 consolidated cortical and subcortical regions were selected as regions of interest (ROIs) by a functional neurosurgeon and DTI values for each ROI were calculated and compared with the corresponding ROI in the opposite hemisphere. Also, track density imaging (TDI) of 68 white matter parcels were generated using fiber orientation distribution (FOD) based deterministic fiber tracking and compared with contralateral side of the brain in each epileptic group: left mesial temporal sclerosis (LMTS) and right MTS (RMTS)). In patients with LMTS, MD and RD values of the left hippocampus decreased significantly using two-tailed t-test (p = 0.03 and p = 0.01 respectively) compared to the right hippocampus. Also, RD showed a marginally significant decrease in left amygdala (p = 0.05). DTT analysis in LMTS shows a marginally significant decrease in the left white matter supramarginal parcel (p = 0.05). In patients with RMTS, FA showed a significant decrease in the ipsilateral mesial temporal lobe (p = 0.02), parahippocampal area (p = 0.03) and thalamus (p = 0.006). RD showed a marginally significant increase in the ipsilateral hippocampus (p = 0.05) and a significant increase in the ipsilatera...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hemispheric Regional Based Analysis of Diffusion Tensor Imaging and Diffusion Tensor Tractography in Patients with Temporal Lobe Epilepsy and Correlation with Patient outcomes

Alizadeh

Kozlowski

Muller

et al. 2019

Sci Rep

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“…Consistently, it has been shown that WM changes associated with TLE are not restricted to the affected medial temporal lobe and involve a larger epileptogenic network (5, 6), reflecting underlying seizure-related WM alterations. Numerous neuroimaging studies on unilateral TLE revealed further temporal and extra-temporal WM changes (7–10).…”

Section: Introductionmentioning

confidence: 99%

Distinctive Patterns of Seizure-Related White Matter Alterations in Right and Left Temporal Lobe Epilepsy

et al. 2019

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Background: We hypothesized that right and left temporal lobe epilepsy (RTLE and LTLE, respectively) have distinctive spatial patterns of white matter (WM) changes that can be differentiated and interpreted with the use of multiple diffusion parameters. We compared the global microstructure of fiber bundles with regard to WM alterations in both RTLE and LTLE, addressing some of the methodological issues of previous studies.Methods: Diffusion tensor imaging data from 17 patients with RTLE (age: 40.7 ± 10.4), 15 patients with LTLE (age: 37.3 ± 10.4), and 15 controls (age: 34.8 ± 11.2) were used in the study. WM integrity was quantified by fractional anisotropy (FA), mean diffusivity (MD), longitudinal diffusivity (LD), and radial diffusivity (RD). The diffusion parameters were compared between the groups in tracts representing the core of the fiber bundles. The volumes of hippocampi and amygdala were subsequently compared across the groups, while the data were adjusted for the effect of hippocampal sclerosis.Results: Significantly reduced FA and increased MD, LD, and RD were found bilaterally over widespread brain regions in RTLE. An increase in MD and RD values was observed in widespread WM fiber bundles ipsilaterally in LTLE, largely overlapping with regions where FA was lower, while no increase in LD was observed. We also found a difference between the LTLE and RTLE groups for the right hippocampal volume (with and without adjustment for HS), whereas no significant volume differences were found between patients and controls.Conclusions: It appears that patients with RTLE exhibit a more widespread pattern of WM alterations that extend far beyond the temporal lobe in both ipsilateral and contralateral hemisphere; furthermore, these changes seem to reflect more severe damage related to chronic degeneration. Conversely, more restrained changes in the LTLE may imply a pattern of less severe axonal damage, more restricted to ipsilateral hemisphere. Comprehensive finding of more prominent hippocampal atrophy in the RTLE raises an interesting issue of seizure-induced implications on gray matter and WM microstructure that may not necessarily mean a straightforward causal relationship. Further correlations of diffusion-derived metrics with neuropsychological and functional imaging measures may provide complementary information on underlying WM abnormalities with regard to functional hemispheric specialization.

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“…To some extent, this has been performed with PET used together with BOLD [13,14] MR imaging during epilepsy imaging evaluation to select patients for resection to lower risk of loss of valuable memory or language function. However, the most common non-conventional imaging MR sequence, diffusion-weighted imaging is rarely utilized [15]. BOLD could be used on future PET/MR cases and correlating it with PET would be a useful direction for further study.…”

Section: Discussionmentioning

confidence: 99%

Subsequent experience in hybrid PET-MRI for evaluation of refractory focal onset epilepsy

Oldan

Shin

Khandani

et al. 2018

Seizure

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Investigation of microstructural abnormalities in white and gray matter around hippocampus with diffusion tensor imaging (DTI) in temporal lobe epilepsy (TLE)

Cited by 21 publications

References 17 publications

Hemispheric Regional Based Analysis of Diffusion Tensor Imaging and Diffusion Tensor Tractography in Patients with Temporal Lobe Epilepsy and Correlation with Patient outcomes

Hemispheric Regional Based Analysis of Diffusion Tensor Imaging and Diffusion Tensor Tractography in Patients with Temporal Lobe Epilepsy and Correlation with Patient outcomes

Distinctive Patterns of Seizure-Related White Matter Alterations in Right and Left Temporal Lobe Epilepsy

Subsequent experience in hybrid PET-MRI for evaluation of refractory focal onset epilepsy

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