title: Fractional anisotropy asymmetry and the side of seizure origin for partial onset-temporal lobe epilepsy.
abstract: This paper presents a fractional anisotropy asymmetry (FAA) method to detect the asymmetry of white matter (WM) integrity and its correlation with the side of seizure origin for partial onset temporal lobe epilepsy (TLE) using diffusion tensor image (DTI). In this study, FAA analysis is applied to 30 patients of partial TLE (15 left, 15 right) and 14 matched normal controls. Specifically, after registering all the images with the JHU-DTI-MNI template the average FA value of each FA skeleton section is calculated using the tract-based spatial statistics (TBSS) method. Then, FAA is calculated to quantify the WM diffusivity asymmetry of the corresponding region-pairs between the left and right hemispheres. Using FAA the regional asymmetry contributing significantly to the group differences of controls and left/right TLE, as well as the left and right TLE, is identified. As a comparison, the ROI-based average FA values for WM and corresponding FAAs are also calculated. TBSS-based analysis reflects the average of local maximal FA values along the white matter skeleton sections, and ROI-based analysis shows the average of WM FA values within each anatomical region. The FAA statistical results indicated that the FA values of anatomical region-pairs are asymmetric in the ipsilateral hemisphere with seizure origin against the contralateral hemisphere. Particularly, FAA values within the temporal lobe (superior, middle, and inferior temporal WM) are significantly different between the left and right TLE patients, consistently found from both analysis methods. The study suggests that FAA values can be potentially used to identify the seizures of origin of TLE and to help understand the relationship between fiber tracts with the side of seizure origin of TLE.
authors.affiliation: Department of Systems Medicine and Bioengineering, Houston Methodist Research Institute, Weill Cornell Medical College, Houston, TX, United States; Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Science, Hefei, China.
authors.forename: Hai
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Systems Medicine and Bioengineering, Houston Methodist Research Institute, Weill Cornell Medical College, Houston, TX, United States. Electronic address: zxue@houstonmethodist.org.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Xue
authors.affiliation: Department of Neurosurgery, Houston Methodist Hospital, Weill Cornell Medical College, Houston, TX, United States.
authors.forename: Mario F
authors.initials: MF
authors.lastname: Dulay
authors.affiliation: Department of Neurosurgery, Houston Methodist Hospital, Weill Cornell Medical College, Houston, TX, United States.
authors.forename: Amit
authors.initials: A
authors.lastname: Verma
authors.affiliation: Department of Neurosurgery, Houston Methodist Hospital, Weill Cornell Medical College, Houston, TX, United States.
authors.forename: Christof
authors.initials: C
authors.lastname: Karmonik
authors.affiliation: Department of Neurosurgery, Houston Methodist Hospital, Weill Cornell Medical College, Houston, TX, United States.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Grossman
authors.affiliation: Department of Systems Medicine and Bioengineering, Houston Methodist Research Institute, Weill Cornell Medical College, Houston, TX, United States.
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Wong
mesh_terms: D000328:Adult; D016880:Anisotropy; D056324:Diffusion Tensor Imaging; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D012640:Seizures / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014463:Ultrasonography
keywords: Diffusion tensor imaging (DTI); Fractional anisotropy asymmetry (FAA); Temporal lobe epilepsy; Tract-based spatial statistics (TBSS)