Voxel-based analysis of diffusion tensor imaging in patients with mesial temporal lobe epilepsy

Sanches, Patrícia; Fujisao, Elaine Keiko; Braga, Aline M.S.; Cristaldo, Nathalia Raquel; Reis, Roberto dos; Yamashita, Seizo; Betting, Luiz Eduardo

doi:10.1016/j.eplepsyres.2017.03.004

Cited by 8 publications

(5 citation statements)

References 35 publications

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“…Prior TLE research involving DTI has shown microstructural abnormalities at the whole hippocampal level 8,9 . Studies using whole brain voxelwise analysis and tract‐based spatial statistics have found that FA and radial diffusivity (RD) are more commonly abnormal in TLE patients than other metrics such as axial diffusivity (AD) and MD 10 . In the immediate postictal period, some inconsistent changes in apparent diffusion coefficient 11,12 and MD have been reported 8,13 .…”

Section: Introductionmentioning

confidence: 99%

“…8,9 Studies using whole brain voxelwise analysis and tract-based spatial statistics have found that FA and radial diffusivity (RD) are more commonly abnormal in TLE patients than other metrics such as axial diffusivity (AD) and MD. 10 In the immediate postictal period, some inconsistent changes in apparent diffusion coefficient 11,12 and MD have been reported. 8,13 In the interictal period, a previous meta-analysis found decreased FA and increased MD in the ipsilateral side at the group level.…”

Section: Introductionmentioning

confidence: 99%

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High‐resolution hippocampal diffusion tensor imaging of mesial temporal sclerosis in refractory epilepsy

et al. 2022

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We explore the possibility of using diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) to discern microstructural abnormalities in the hippocampus indicative of mesial temporal sclerosis (MTS) at the subfield level. Methods:We analyzed data from 57 patients with refractory epilepsy who previously underwent 3.0-T magnetic resonance imaging (MRI) including DTI as a standard part of presurgical workup. We collected information about each subject's seizure semiology, conventional electroencephalography (EEG), highdensity EEG, positron emission tomography reports, surgical outcome, and available histopathological findings to assign a final diagnostic category. We also reviewed the radiology MRI report to determine the radiographic category. DTIand NODDI-based metrics were obtained in the hippocampal subfields.Results: By examining diffusion characteristics among subfields in the final diagnostic categories, we found lower orientation dispersion indices and elevated axial diffusivity in the dentate gyrus in MTS compared to no MTS. By similarly examining among subfields in the different radiographic categories, we found all diffusion metrics were abnormal in the dentate gyrus and CA1. We finally examined whether diffusion imaging would better inform a radiographic diagnosis with respect to the final diagnosis, and found that dentate diffusivity suggested subtle changes that may help confirm a positive radiologic diagnosis. Significance:The results suggest that diffusion metric analysis at the subfield level, especially in dentate gyrus and CA1, maybe useful for clinical confirmation of MTS.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High‐resolution hippocampal diffusion tensor imaging of mesial temporal sclerosis in refractory epilepsy

et al. 2022

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“…The most widely applied DWI technique is diffusion tensor imaging (DTI), which provides measures of fractional anisotropy (FA) and mean diffusivity (MD) that have been interpreted as microstructural indices of white matter structural integrity (2,3). However, many features of tissue microstructure, both biophysical as well as neuropathological (4)(5)(6)(7)(8), can alter FA and MD in similar ways and thereby limit our ability to more specifically associate changes in white matter structural integrity to the specific molecular and cellular changes that underlie complex neurologic and neuropsychiatric disorders. In an effort to obtain greater specificity and to advance our understanding of white matter microstructure from the diffusion signal, modern DWI methods employ a multi-compartment approach that (i) considers the signal in a voxel to be the sum of contributions from several different compartments and (ii) models the signal from each compartment as biologically salient features of tissue microstructure such as a neuronal (intracellular) compartment and an extra-axonal (extracellular) compartment (9).…”

Section: Introductionmentioning

confidence: 99%

Microglial Density Alters Measures of Axonal Integrity and Structural Connectivity

Stowe

Barnett

et al. 2020

Biological Psychiatry: Cognitive Neuroscience and Neuroimaging

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“…Several studies employed TBSS to evaluate WM changes in TLE patients in comparison to healthy controls (9, 12–14); however, most of the reported TLE-related WM alterations were described without consideration of the affected side or possible discrepancies resulting from lateralization of brain function. We hypothesized that right and left TLE (RTLE and LTLE, respectively) have different spatial patterns of WM changes that can be differentiated and interpreted with the use of multiple diffusion parameters.…”

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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Voxel-based analysis of diffusion tensor imaging in patients with mesial temporal lobe epilepsy

Cited by 8 publications

References 35 publications

High‐resolution hippocampal diffusion tensor imaging of mesial temporal sclerosis in refractory epilepsy

High‐resolution hippocampal diffusion tensor imaging of mesial temporal sclerosis in refractory epilepsy

Microglial Density Alters Measures of Axonal Integrity and Structural Connectivity

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

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