Introduction: Our objective was to quantify the connectivity strength (based on probabilistic DTI) of fiber tracts that originate in the seizure onset region (based on intracranial ECoG) and that project to remote cortical areas characterized by F18-deoxyglucose (FDG) PET abnormalities that are electrophysiologically normal.

Methods: We developed a computational framework that allows quantitative assessment of the spatial relationship between multi-modality neuroimaging data (PET, DTI, ECoG). The framework is based on the parcellation of the cortical surface in native space using landmark-constrained conformal mapping, which yields finite cortical elements (FCEs) that are homotopic across subjects. The FCEs were used as source/target regions for probabilistic fiber tracking (55 direction), allowing the calculation of a connectivity score (CS). We applied this approach to 7 young children (3–12 yrs) with non-lesional epilepsy and compared the obtained connectivity pattern against 12 age-matched normal children.

Results: CS reproducibility was assessed in the normal group for three major fiber tracts (arcuate, SLF and ILF), yielding a COV of 5.3 + 4.7%. Comparison of the CS between the normal group and the patient group showed either unchanged or decreased CS for major fiber tracts, with the decreases more pronounced on the ipsilateral side (22% vs. 14%). Connectivity strength analysis between the epileptogenic cortex and remote FDG PET abnormalities showed a similar pattern with highly significant decreases in both ipsi- (>80%) and contralateral (~50%) hemisphere.

Conclusion: Our findings indicate that fiber connectivity between the primary focus and remote FDG PET abnormalities is significantly decreased as compared to controls.