HIGH RESOLUTION DIFFUSION TENSOR IMAGING IN PATIENTS WITH CORTICAL DYSPLASIA - A STUDY AT 3 TESLA
Abstract number :
B.03
Submission category :
Year :
2003
Submission ID :
3588
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
M. Halko, S. Knake, P.E. Grant, D.H. Salat, D.S. Tuch, S.S. Stufflebeam, H. Shriaishi, E.B. Bromfield, D.L. Schomer, E. Halgren MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charles
Cortical dysplasias (CD) are a common cause of epilepsy that are associated with pathologic cortical and white matter organization. The ability to localize focal cortical dyplasia considerably modifies the postsurgical outcome. The aim of this study is to investigate whether DTI is able to detect subtle microstructural changes in the white matter (wm) organization associated with CD.
Five patients (mean age 25.2 years) with temporal lobe epilepsy (TLE) and CD in the affected temporal lobe and three patients (mean age 25.3 y) with focal, non-lesional, extra temporal epilepsies (ETE) were investigated. In 3 of the TLE patients, the diagnosis of CD was confirmed histologically. CD have been diagnosed using an 8-channal array surface coil MRI. DTI was collected using a multi-shot high-resolution echo-planar imaging technique (2 mm slices), gap 0 mm, TR = 12000 ms, TE = 69 ms, 128x128 acquisition matrix, b-value 700 s/mm2) with a 3T whole body scanner (Siemens Trio, Siemens, Erlangen, Germany). Diffusion weighted images were acquired during an 8 min scan with 60 averages. Whole brain fractional anisotropy (FA)-maps were coregistered to a low-b image. Mean FA was calculated within a 5mm diameter spherical region of interest (ROI) deep in the central white matter of the temporal lobe in all patients. The fractional change ratio was defined by subtracting the FA from the pathologic side from the one of the healthy side and dividing it by the FA of the normal side.
CD showed significantly widespread increased FA-values despite smaller visible detectable lesions in the ROI of the affected side (p=0.014). Table 1 gives an overview of the results. The mean difference was 0.15. There were no hemispheric differences in ETE (p=0.4).
DTI seems to be a promising, non-invasive tool to detect even subtle structural changes of white matter organization. The method needs further validation seems to be a promising new tool, especially for detecting CD in patients with non-lesional focal epilepsies and might be integrated in the presurgical workup in the future. [table1]
[Supported by: MIND Institute]