The Role of MRI in the Treatment of Drug-Resistant Focal Epilepsy

Abstract

<b><i>Background:</i></b> Epilepsy is a prevalent chronic condition affecting about 50 million people worldwide. A third of patients with focal epilepsy suffer from seizures unresponsive to medication. Uncontrolled seizures damage the brain, are associated with cognitive decline, and have negative impact on well-being. For these patients, the surgical resection of the brain region that gives rise to seizures is the most effective treatment. <b><i>Summary:</i></b> Magnetic resonance imaging (MRI) plays a central role in detecting epileptogenic brain lesions. In this review, we critically discuss advances in neuroimaging acquisition, analytical post-acquisition techniques, and machine leaning methods for the detection of epileptogenic lesions, prediction of clinical outcomes, and identification of disease subtypes. <b><i>Key Message:</i></b> MRI is a mandatory investigation for diagnosis and treatment of epilepsy, particularly when surgery is being considered. Continuous progress in imaging techniques, combined with machine learning, will continue to push the boundaries of lesion visibility and provide increasingly precise predictors of clinical outcomes. Current efforts aiming at strengthening the competences of epileptologists in neuroimaging will ultimately reduce the need for invasive diagnostics.

Impact of an optimized epilepsy surgery imaging protocol for focal epilepsy: A monocentric prospective study

“…This rate is in line with previous data 6,10,33 . Many patients have subtle lesions that might be undetected on routine MRI but have an histopathological correlation 9,33 . The crucial need to detect surgically amenable lesions in patients with focal epilepsy has motivated the development of sophisticated detection methods 27,34–36 .…”

“…In 2002, von Oertzen and colleagues 11 pointed that the application of an epilepsytailored MRI protocol plus an expert neuroradiologist reading resulted in a failure rate significantly lower than a "standard" MRI and nonexperts reports (9% in the former situation versus 61% in the latter). Similar conclusions were reported later 8,9,18 and different time-effective epilepsy-MRI protocol for drug-resistant epilepsy have been published so far. [11][12][13]18,19 A recent systematic review and meta-analysis demonstrated that a dedicated MRI protocol benefits the detection rate in epilepsy surgery candidates, particularly for FCD.…”

“…6,10,33 Many patients have subtle lesions that might be undetected on routine MRI but have an histopathological correlation. 9,33 The crucial need to detect surgically amenable lesions in patients with focal epilepsy has motivated the development of sophisticated detection methods. 27,[34][35][36] Our findings by confirming a relatively consistent rate of MRI negative even adopting an optimized protocol, highlights the intrinsic limits of the visual MRI inspection and support, in specific situations, the efforts of computer-aided methods to contribute revealing the structural lesion.…”

“…Previous studies showed that 30%–46% of examinations at first considered MRI negative were instead positive (i.e., with a lesion linked to the patient's epilepsy) after improved MRI acquisition (field strength and sequence selection) and/or experienced evaluation 7,8 . Furthermore, lesions might not be visible on MRI but can have histopathological correlates 9 …”

“…7,8 Furthermore, lesions might not be visible on MRI but can have histopathological correlates. 9 In 2019, the International League Against Epilepsy (ILAE) published the official recommendation of structural MRI for focal epilepsy. 10 In that, the following sequences were recommended as the minimum required protocol: 3D millimetric T1-weighted images (T1WI) and fluid-attenuated inversion recovery (FLAIR) images, and 2D sub millimetric coronal T2-weighted images (T2WI) acquired perpendicular to the long axis of the hippocampus.…”