Ablation of apparent diffusion coefficient hyperintensity clusters in mesial temporal lobe epilepsy improves seizure outcomes after laser interstitial thermal therapy

Min Jae Kim; Brian Hwang; David Mampre; Serban Negoita; Yohannes Tsehay; Haris Sair; Joon Y Kang; William S Anderson

doi:10.1111/epi.17432

Ablation of apparent diffusion coefficient hyperintensity clusters in mesial temporal lobe epilepsy improves seizure outcomes after laser interstitial thermal therapy

Epilepsia. 2023 Mar;64(3):654-666. doi: 10.1111/epi.17432. Epub 2023 Jan 12.

Authors

Min Jae Kim^{1

2

3}, Brian Hwang¹, David Mampre⁴, Serban Negoita¹, Yohannes Tsehay¹, Haris Sair⁵, Joon Y Kang², William S Anderson^{1

3}

Affiliations

¹ Department of Neurosurgery, Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
² Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
³ Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
⁴ Department of Neurosurgery, University of Florida College of Medicine, Gainesville, Florida, USA.
⁵ Department of Radiology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA.

PMID: 36196769
DOI: 10.1111/epi.17432

Abstract

Objective: Laser interstitial thermal therapy (LiTT) is a minimally invasive surgical procedure for intractable mesial temporal epilepsy (mTLE). LiTT is safe and effective, but seizure outcomes are highly variable due to patient variability, suboptimal targeting, and incomplete ablation of the epileptogenic zone. Apparent diffusion coefficient (ADC) is a magnetic resonance imaging (MRI) sequence that can identify potential epileptogenic foci in the mesial temporal lobe to improve ablation and seizure outcomes. The objective of this study was to investigate whether ablation of tissue clusters with high ADC values in the mesial temporal structures is associated with seizure outcome in mTLE after LiTT.

Methods: Twenty-seven patients with mTLE who underwent LiTT at our institution were analyzed. One-year seizure outcome was categorized as complete seizure freedom (International League Against Epilepsy [ILAE] Class I) and residual seizures (ILAE Class II-VI). Volumes of hippocampus and amygdala were segmented from the preoperative T1 MRI sequence. Spatially distinct hyperintensity clusters were identified in the preoperative ADC map. Proportion of cluster volume and number ablated were associated with seizure outcomes.

Results: The mean age at surgery was 37.5 years and the mean follow-up duration was 1.9 years. Proportions of hippocampal cluster volume (p = .013) and number (p = .03) ablated were significantly higher in patients with seizure freedom. For amygdala clusters, the proportion of cluster number ablated was significantly associated with seizure outcome (p = .026). In the combined amygdalohippocampal complex, ablation of amygdalohippocampal clusters reliably predicted seizure outcome by their volume ablated (area under the curve [AUC] = 0.7670, p = .02).

Significance: Seizure outcome after LiTT in patients with mTLE was associated significantly with the extent of cluster ablation in the amygdalohippocampal complex. The results suggest that preoperative ADC analysis may help identify high-yield pathological tissue clusters that represent epileptogenic foci. ADC-based cluster analysis can potentially assist ablation targeting and improve seizure outcome after LiTT in mTLE.

Keywords: ADC; LiTT; diffusion weighted imaging; epilepsy surgery; mTLE; seizure prediction.

MeSH terms

Drug Resistant Epilepsy* / surgery
Epilepsy, Generalized* / pathology
Epilepsy, Temporal Lobe* / surgery
Hippocampus / pathology
Humans
Laser Therapy* / methods
Lasers
Magnetic Resonance Imaging / methods
Seizures / pathology
Temporal Lobe / surgery
Treatment Outcome