[18F]DPA-714 PET Imaging in the Presurgical Evaluation of Patients With Drug-Resistant Focal Epilepsy

Abstract

Background and objectives: Translocator protein 18 kDa (TSPO) PET imaging is used to monitor glial activation. Recent studies have proposed TSPO PET as a marker of the epileptogenic zone (EZ) in drug-resistant focal epilepsy (DRFE). This study aims to assess the contributions of TSPO imaging using [¹⁸F]DPA-714 PET and [¹⁸F]FDG PET for localizing the EZ during presurgical assessment of DRFE, when phase 1 presurgical assessment does not provide enough information.

Methods: We compared [¹⁸F]FDG and [¹⁸F]DPA-714 PET images of 23 patients who had undergone a phase 1 presurgical assessment, using qualitative visual analysis and quantitative analysis, at both the voxel and the regional levels. PET abnormalities (increase in binding for [¹⁸F]DPA-714 vs decrease in binding for [¹⁸F]FDG) were compared with clinical hypotheses concerning the localization of the EZ based on phase 1 presurgical assessment. The additional value of [¹⁸F]DPA-714 PET imaging to [¹⁸F]FDG for refining the localization of the EZ was assessed. To strengthen the visual analysis, [¹⁸F]DPA-714 PET imaging was also reviewed by 2 experienced clinicians blind to the EZ location.

Results: The study included 23 patients. Visual analysis of [¹⁸F]DPA-714 PET was significantly more accurate than [¹⁸F]FDG PET to both, show anomalies (95.7% vs 56.5%, p = 0.022), and provide additional information to refine the EZ localization (65.2% vs 17.4%, p = 0.019). All 10 patients with normal [¹⁸F]FDG PET had anomalies when using [¹⁸F]DPA-714 PET. The additional value of [¹⁸F]DPA-714 PET seemed to be greater in patients with normal brain MRI or with neocortical EZ (especially if insula is involved). Regional analysis of [¹⁸F]DPA-714 and [¹⁸F]FDG PET provided similar results. However, using voxel-wise analysis, [¹⁸F]DPA-714 was more effective than [¹⁸F]FDG for unveiling clusters whose localization was more often consistent with the EZ hypothesis (87.0% vs 39.1%, p = 0.019). Nonrelevant bindings were seen in 14 of 23 patients in visual analysis and 9 patients of 23 patients in voxel-wise analysis.

Discussion: [¹⁸F]DPA-714 PET imaging provides valuable information for presurgical assessments of patients with DRFE. TSPO PET could become an additional tool to help to the localization of the EZ, especially in patients with negative [¹⁸F]FDG PET.

Trial registration information: Eudract 2017-003381-27. Inclusion of the first patient: September 24, 2018.

Classification of evidence: This study provides Class IV evidence on the utility of [¹⁸F]DPA-714 PET compared with [¹⁸F]FDG PET in identifying the epileptic zone in patients undergoing phase 1 presurgical evaluation for intractable epilepsy.