Dynamic assessment of high-resolution MRI with multi-planar reconstruction increases the yeld of lesion detection in patients with patial epilepsy

RESUMO

To investigate the presence and type of lesions associated with partial epilepsies by routine high resolution MRI and multi-planar reconstruction (MPR) and correlate the MRI abnormalities with semiology and EEG findings. We studied 100 consecutive patients followed in the epilepsy clinic of our Hospital with partial epilepsy who underwent MRI investigation. THE MRI protocol included 6 mm sagittal T1-weighted, 3-4 mm axial T1 and T2-weighted, 3 mm coronal T1 inversion recovery and T2-weighted images that were printed on a radiographic film for routine analysis. The clinical and EEG findings were tabulated independently, and results were comapred using Chi-square of Fisher exact test when appropriate. The patients were divided into 10 groups according to their etiological classification (structural lesions) establihed by MRI. Mesial temporal sclerosis (MTS) was the largest group (40 per cent). There were 65 women and 35 men. Mean age was 23.9 (+- 5.7) years and mean age of onset of recurrent seizures was 9.9 (+-0.8) years. The most frequent risk factors were family history of seizures (23 per cent), head trauma (10 per cent), peri-natal anoxia (5 per cent) and infection (9 per cent). High resolution MRI including thin coronal slices, in addition to a "dynamic" analysis in a workstation with MPR, allowed a significant improvement in lesion detection compared to the traditional analysis with radiographic films (94 per cent versus 80 per cent) (p<0.05). The lesions previously undetected were focal cortical dysplasia and subtle MTS. There was a good concordance between MRI lesions and clinical and EEG findings. High resolution MRI including thin coronal slices, in addition to a "dynamic" analysis in a workstation with MPR allowed a significative improvement in lesion detection compared to the traditional analysis with radiographic films 94 per cent versus 80 per cent). Patients with partial epilepsy and "normal" MRI need to to investigated further with thin slices and post-processing techniques using volume acquisitions tha allow adequate multi-planar re-slicing