Authors :
Presenting Author: Callum Taylor, BS, Hons – Monash
Janet Leung, PhD – Monash
Pablo Casillas-Espinosa, MD, PhD – Monash University
Mathew Heald, PhD – Cyclotek
Robert brkljaca, PhD – Monash
Terrence J. O'Brien, MB, BS, MD, FRACP, FRCPE, FAHMS, FAES – Monash University, Melbourne, VIC, Australia
Bianca Jupp, PhD – Monash
Rationale:
Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy and has high rates of drug resistance. Often, resective surgery to remove the epileptogenic zone (EZ) is the only way to achieve seizure freedom, however, this relies on the accurate delineation of the EZ. e. Traditionally, research in epilepsy has focussed on neuronal dysfunction, however, there is increasing interest in the role of astrogliosis in epilepsy. [18F]F-DED is a novel positron emission tomography (PET) tracer which is specific to monoamine oxidase B (MAO-B), and can image astrogliosis in the living brain. This study investigated 18F-FDED PET as a tool for imaging astrogliosis in an animal model and patients with TLE.
Methods:
90-minute dynamic [18F]-FDED PET scans were acquired from male Sprague-Dawley rats from a kainic acid status epilepticus (KASE) cohort (n=17) or controls (n=13), with scans performed at 1, 4, and 8 weeks post-kainic acid administration. Following the final scan, animals underwent video electroencephalography (vEEG) for 1 week to confirm recurrent seizure.
7 patients with unilateral drug resistant TLE and hippocampal sclerosis, (including one with dysembryoplastic neuroepithelial tumour) as well as 4 healthy controls underwent 60-minute dynamic PET scans with [18F]F-DED. Blinded visual assessment of FDED SUV images, were independently assessed by 2 raters to attempt to localise the EZ. Localisation rate was then compared with FDG PET.
Results:
[18F]F-DED %ID was not seen to be significantly different between epileptic and control rats in any brain region.
The EZ correctly localised in 3/7 (~43%) patients using [18F]F-DED, with disagreements between raters in 3/7 (~43%), and 1/7 not localised. In those correctly localised high uptake was seen unilaterally in the mesial temporal lobe (FIGURE 1). All controls 4/4, 100%) were correctly identified. FDG PET correctly localised the EZ in all patients (7/7, 100%).
Figure 1: SUV image of [18F]F-DED PET in a patient with drug resistant TLE demonstrating increased uptake in the left hippocampus
Conclusions:
[18F]F-DED uptake was not seen to be significantly different between epileptic and control rats in a rodent model of TLE, however, improved modelling will allow for full quantification of [18F]F-DED and may elucidate changes between the epileptic and non-epileptic brain.
[18F]F-DED PET was able to be used to identify the EZ in patients with drug resistant TLE. Pharmacokinetic modelling of [18F]F-DED PET is ongoing and may improve localisation rates.
Funding: NA