Epileptogenic lesions in the Australian epilepsy project: A harmonized 3-T magnetic resonance imaging protocol and its diagnostic yield.
TL;DR
The AEP 3-T MRI research protocol is feasible at multisite national scale, and sensitive for detection of subtle lesions when read by neuroradiologists with expertise in epilepsy.
Abstract
Objective
Detection of epilepsy-causing structural brain lesions on magnetic resonance imaging (MRI) is critical for diagnosis, prognosis, and treatment planning in people with epilepsy. We aimed to establish an epilepsy-directed multisite harmonized 3-T MRI acquisition protocol for the Australian Epilepsy Project (AEP) and describe the clinical structural brain findings in the initial participant cohort.
Methods
The AEP MRI protocol was designed to meet clinical diagnostic and research needs. It includes HARNESS-MRI sequences plus targeted views (temporal pole), susceptibility and diffusion imaging, quantitative measurements (T1, T2), and selected functional MRI tasks. A total of 1330 adults were enrolled and completed imaging assessment at seven sites. Diagnoses at referral were 146 people with first unprovoked seizure only (FUS), 325 with newly diagnosed epilepsy (NDE), 468 with drug-resistant focal epilepsy (DRE), and 391 healthy controls. Imaging data were curated via a centralized platform, relevant sequences were clinically reported by subspecialist epilepsy neuroradiologists, and the report findings were classified. Findings were compared to prior reports from standard clinical MRI.
Results
A structural brain lesion considered to be epileptogenic was detected in 12% in FUS, 18% in NDE, and 39% in DRE, compared with 2% in healthy controls. The most common epileptogenic lesions included hippocampal sclerosis, acquired cortical injury, malformations of cortical development, long-term epilepsy associated tumors, and vascular malformations. Potentially epileptogenic lesions included temporal pole encephaloceles, which were detected in 12% of epilepsy participants versus 7% of healthy controls. In 682 participants with an available prior clinical MRI report, 62 (9.1%) had a new epileptogenic lesion detected on the AEP scan, indicating greater sensitivity of the AEP imaging and reporting process for detection of epileptogenic lesions over standard care (p < .001).
Significance
The AEP 3-T MRI research protocol is feasible at multisite national scale, and sensitive for detection of subtle lesions when read by neuroradiologists with expertise in epilepsy. When added to current Australian clinical practice, this strategy yields significantly more epileptogenic findings.