Abstracts

To assess the additional value of 3Tesla (T) magnetic resonance imaging (MRI) and surface coils for the detection and characterization of cerebral lesions in patients with drug resistant epilepsy.
About 30% are refractory to pharmacological treatment and neurosurgical intervention is then an option. Malformation of cortical development is the second most common histopathological finding in these patients. Optimal pre-operative radiological imaging is imperative as it addresses both diagnostic and prognostic issues., 25 patients (mean age 19 years, range 4-51 years) with drug resistant epilepsy undergoing evaluation for epilepsy surgery were examined with high resolution MRI to further improve the morphological evaluation of the brain, especially the cortex. They had previously been examined with MRI at 1.5T or lower field strength. MRI was performed with a 3T scanner (Philips Intera) using a 4-channel head coil and parallel imaging. The protocol included T2-weighted FLAIR and T1-weighted 3D gradient echo sequences covering the entire brain and T1-weighted inversion recovery (IR) sequences in 2 planes covering the region with the suspected epileptogenic zone. In addition, surface coils were applied over the latter region
In MRI negative patients placement of the coils was defined by semiological analysis and extracranial video-EEG, and in selected cases subtraction ictal SPECT co-registered with MRI or by PET. All images were retrospectively evaluated with knowledge of the lateralization of the suspected epileptogenic zone., Pathology was detected on 3T MRI in 12 patients (50%) and no abnormalities were found in the remaining13 patients. The identified, possibly epileptogenic, lesions were cortical dysplasia in 6, heterotopic gray matter in 1, hippocampal sclerosis in 3, white matter lesions in 1, and atrophy in 1 patient. 3T MRI provided new or additional information about the cortex, compared with reports from previous MRI, in 4 patients: 1 patient, previously judged normal, revealed malformation of cortical development (MCD). 3 patients with findings previously characterized as unspecific were classified as MCD. Surface Coil MRI visualized the cortical lesions with somewhat better demarcation and detail, but did not contribute to detection of previously undiagnosed lesions or added information regarding type of lesion in any of the cases reviewed in this study, 3T MRI with high resolution is superior to 1,5T MRI for the detection and characterization of structural lesions, particularly MCD:s, in patients with drug resistant epilepsy. Surface coil imaging at 3T does not provide additional information that would influence the therapeutic decisions.,