Abstracts

Rationale: The long term effects of chronic temporal lobe epilepsy (TLE) on memory and cognition are incompletely understood. There are progressive global and regional changes in brain structure and function in patients with TLE which are similar to pathophysiological changes in Alzheimer s disease, including senile plaque deposition. (Mackenzie IR, Miller LA. Senile plaques in temporal lobe epilepsy. Acta Neuropathol (Berl) 1994;87:504-10., Noebels J. A perfect storm: Converging paths of epilepsy and Alzheimer's dementia intersect in the hippocampal formation. Epilepsia 2011;52 Suppl 1:39-4) Florbetapir PET/CT imaging is a relatively new FDA-approved imaging technique that provides the ability to detect the presence and location of amyloid in the brain. We chose to use this technology to investigate perfusion patterns of dynamic uptake as well as amyloid deposition in the whole brain of patients with chronic TLE. We report preliminary findings showing perfusion changes.Methods: We plan to recruit ten subjects with chronic TLE. To be included, a subject should be at least twenty years old, have had epilepsy for at least 20 years, and have EEG and MRI findings which support TLE. Subjects who have already undergone epilepsy surgery, have a history of a significant head trauma or chronic alcohol abuse, have another significant neurological disorder other than epilepsy, women who were pregnant or breastfeeding, and those found to be apolipoprotein E4 homozygotes were excluded. Well-selected subjects underwent a 60 minute dynamic PET/CT scan starting immediately after intravenous injection of Florbetapir with the following framing sequence: 4 x 15 seconds, 4 x 30 seconds, 3 x 60 seconds, 3 x 120 seconds, 2 x 240 seconds, 8 x 5 minutes. Initial perfusion patterns were qualitatively assessed by a blinded neuroradiologist (JM) trained to clinically interpret Florbetapir imaging. Perfusion patterns were correlated with EEG and MRI data to assess for concordance of localizing findings.Results: Three subjects have completed the study. Qualitative comparison of sequentially-timed dynamic uptake images following Florbetapir injection revealed temporal hypoperfusion ipsilateral to the epileptogenic side within the first 1-2 minutes of the scan in two out of three cases. The third case revealed no lateralized perfusion pattern.Conclusions: Preliminary data analysis suggests that dynamic Florbetapir PET/CT started immediately after injection may reveal similar hypoperfusion patterns compared to other functional imaging modalities used in the evaluation of TLE. Initial changes in perfusion seen with Florbetapir PET/CT may be an important factor in quantitative analysis of amyloid deposition and interpretation of results.