Mazyar Eghbal Ahmadi MD, Presenter: Nothing to Disclose

Donald Hagler PhD, Abstract Co-Author: Nothing to Disclose

Carrie McDonald, Abstract Co-Author: Nothing to Disclose

Vicente Iragui, Abstract Co-Author: Nothing to Disclose

Anders M. Dale PhD, Abstract Co-Author: Founder, CorTechs Labs, Inc Stockholder, CorTechs Labs, Inc Scientific Advisory Board, CorTechs Labs, Inc

Eric Halgren, Abstract Co-Author: Nothing to Disclose

We wished to use diffusion tensor imaging (DTI) tractography to quantify the extent of white matter pathology in patients with temporal lobe epilepsy (TLE) compared to controls, and determine if the information could assist in lateralization of the seizure focus in pre-surgical patients.

21 TLE patients with lateralized seizure focus (11 left, 10 right) and 21 age/gender/education matched controls were enrolled. Images were scanned using a 1.5 Tesla MR scanner. 51 diffusion gradient directions using b-value of 1,000 mm2/s were obtained in each patient. Cingulum fibers (CG), parahippocampal fibers (PH), superior longitudinal fasciculus (SLF), temporal component of SLF (tSLF), inferior longitudinal fasciculus (ILF), uncinate fasciculus (UF), fornix (FORX), anterior thalamic radiations (ATR), and inferior fronto-occipital fasciculus (IFOF) were traced. Ipsilateral and contralateral fiber fractional anisotropy (FA), and mean diffusivity (MD) were calculated and compared to controls. Within the left and right TLE population, diffusion asymmetry was evaluated.

Compared to controls, TLE population demonstrated decreased fiber FA in the ipsilateral CG, PH, ILF, IFOF, SLF, and tSLF, as well as contralateral PH and IFOF. There was increased fiber MD in the ipsilateral PH, UF, ILF, IFOF, SLF, tSLF, and FORX in the TLE group as compared to controls. Fiber asymmetry was demonstrated in the right TLE group for FA (IFOF, ILF, PH, and CG) and MD (ATR, UF, ILF, IFOF, SLF, tSLF, and FORX.) Left TLE fiber asymmetry was demonstrated for FA (FORX) and MD (CG and UF.)    

We found widespread reductions in fiber FA and gains in MD in TLE patients relative to controls, which were most pronounced ipsilateral to the seizure focus. Interestingly, the degree of fiber asymmetry was more pronounced in patients with right TLE for both FA and MD as compared to the left TLE group. The left TLE patients had greater, more diffuse bilateral white matter changes; whereas, patients with right TLE showed white matter changes that were primarily ipsilateral to their seizure focus.

To delineate TLE versus controls, as-well-as right versus left TLE patients, with overall objective of enhancing existing non-invasive methods of seizure lateralization in pre-surgical patients.

Ahmadi, M, Hagler, D, McDonald, C, Iragui, V, Dale, A, Halgren, E, Diffusion Tensor Imaging Tractography in Temporal Lobe Epilepsy.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6016482.html