Improving Lesion Detection in Children With Magnetic Resonance Imaging (MRI)-Negative Partial Epilepsy Using Diffusion Tensor Imaging
Condition: Localization-related Epilepsy; Partial Epilepsy
MeSH terms: Epilepsy; Epilepsies, Partial
Study type: Observational

Summary: 
      Focal cortical dysplasia is one of the most common lesions responsible for medically
      refractory epilepsy in the pediatric population. In patients with medically intractable
      epilepsy, surgery is the only treatment that will lead to seizure freedom. The outcome of
      epilepsy surgery is worse in patients when there is no lesion identified on routine
      structural MRI, also known as MRI-negative partial epilepsy. Diffusion tensor imaging (DTI),
      a novel MRI technique, can be used to evaluate the integrity of the microstructure of the
      white matter, even when the white matter appears normal on routine MRI.
    

Detailed description: 
      The aims of this study are firstly to identify DTI abnormalities in the white matter of
      children with MRI-negative partial epilepsy and MRI-visible FCD compared to normal controls;
      and secondly to determine if the location of DTI identified abnormalities correlate with the
      epileptogenic zone as defined using magnetoencephalography (MEG) dipole clusters. Our
      hypotheses are firstly DTI can demonstrate the anatomic delineation of white matter
      abnormalities in MRI-negative partial epilepsy and the alteration in DTI indices are similar
      in MRI-negative partial epilepsy and MRI-visible FCD, which is the positive control; and
      secondly the anatomical location of DTI identified abnormalities correlate with the
      epileptogenic zone as defined by MEG dipole clusters. The long-term goal of this study is to
      improve detection of subtle lesions in children with MRI-negative partial epilepsy so as to
      improve the surgical outcome of these patients who undergo epilepsy surgery for seizure
      control.
    

Intervention name(s): Diffusion Tensor Imaging (DTI); Magnetoencephalography
Intervention type(s): Procedure; Procedure
Intervention description(s): MR and DTI: MRI and DTI will be done using 3.0T Philips MR scanner (Philips Medical Systems, Best, The Netherlands) using an eight channel head coil. DTI and axial 3D T1 will be performed on patients and controls.
DTI will be performed using single shot diffusion-weighted echo planar imaging, b=1000s/mm2 and 15 noncollinear directions (TR/TE=10,000/60 ms, slice thickness=2mm, field of view=22cm, matrix=112x112, NEX=2)
Axial 3D T1 (TR/TE=4.9/2.3 ms, slice thickness=1 mm, field of view = 24 cm, matrix=220x220, NEX=1) Patients will have additional sequences (axial and coronal T2, proton density and FLAIR) as part of their clinical scan; MEG will be performed using a whole-head Omega 151-channel gradiometer system (VSM MedTech, Port Coquitalam, BC, Canada). At least 15 2-minute periods of spontaneous data will be recorded with a sampling rate for data acquisition of 625Hz, a bandpass filter of 10 to 70 Hz and a notch filter of 60 Hz.
Other intervention name(s): MEG
Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Patients will be identified from the epilepsy clinic and seizure rounds and who have had
        previous MRI in an outside institution or prior MRI at least two years ago at the Hospital
        for Sick Children.

        Control children will be recruited through hospital publications and from families
        participating in the study (healthy siblings)
      
Keywords: MRI-Negative; Diffusion tensor imaging; Localization-related epilepsy; Partial Epilepsy; Children