Seven tesla MRI improves detection of focal cortical dysplasia in patients with refractory focal epilepsy

Abstract

SummaryObjectiveThe aim of this study is to determine whether the use of 7 tesla (T) MRI in clinical practice leads to higher detection rates of focal cortical dysplasias in possible candidates for epilepsy surgery.MethodsIn our center patients are referred for 7 T MRI if lesional focal epilepsy is suspected, but no abnormalities are detected at one or more previous, sufficient‐quality lower‐field MRI scans, acquired with a dedicated epilepsy protocol, or when concealed pathology is suspected in combination with MR‐visible mesiotemporal sclerosis—dual pathology. We assessed 40 epilepsy patients who underwent 7 T MRI for presurgical evaluation and whose scans (both 7 T and lower field) were discussed during multidisciplinary epilepsy surgery meetings that included a dedicated epilepsy neuroradiologist. We compared the conclusions of the multidisciplinary visual assessments of 7 T and lower‐field MRI scans.ResultsIn our series of 40 patients, multidisciplinary evaluation of 7 T MRI identified additional lesions not seen on lower‐field MRI in 9 patients (23%). These findings were guiding in surgical planning. So far, 6 patients underwent surgery, with histological confirmation of focal cortical dysplasia or mild malformation of cortical development.SignificanceSeven T MRI improves detection of subtle focal cortical dysplasia and mild malformations of cortical development in patients with intractable epilepsy and may therefore contribute to identification of surgical candidates and complete resection of the epileptogenic lesion, and thus to postoperative seizure freedom.

MP2RAGE multispectral voxel‐based morphometry in focal epilepsy

“…Consequently, patients have worse surgical outcomes compared to cases with visible lesions on MRI (Tellez‐Zenteno, Hernandez Ronquillo, Moien‐Afshari, & Wiebe, ). Technical advances of the static magnetic fields from 1.5 to 3 T and higher field strengths of 7 T can aid in detecting epileptogenic lesions that are otherwise difficult to perceive (De Ciantis et al, ; Knake et al, ; Veersema et al, ; Zijlmans et al, ). Also, computational methods have been shown helpful in detecting subtle lesions, previously missed in the visual analysis (Kotikalapudi et al, ; Martin, Bender, & Focke, ; Martin et al, ).…”

“…Technical advances of the static magnetic fields from 1.5 to 3 T and higher field strengths of 7 T can aid in detecting epileptogenic lesions that are otherwise difficult to perceive (De Ciantis et al, 2016;Knake et al, 2005;Veersema et al, 2017;Zijlmans et al, 2009). Also, computational methods have been shown helpful in detecting subtle lesions, previously missed in the visual analysis Martin, Bender, & Focke, 2015;Martin et al, 2017).…”

MP2RAGE and Susceptibility‐Weighted Imaging in Lesional Epilepsy at 7T

“…In the remaining subgroup of 15 patients with known lesions, MRI at 3T allowed for better delineation in 33% . Veersema et al in a series of 40 patients at 7T MRI identified additional lesions in 23% of patients not seen at 1.5 and 3T. The data suggest that higher magnetic field MRI has great potential to identify and better characterize inconspicuous epileptogenic lesions.…”

“…Over the past few years, ultra‐high‐field (UHF) 7T MRI machines have been available in a few research centers for in vivo human brain imaging. The increased signal‐to‐noise ratio, improved spatial structural resolution, and enhanced image contrast allow for better depiction, characterization, and visualization of millimetric anatomical structures and lesions such as FCD than 3T that offers the chance to reveal new features of neurological diseases that may change clinical diagnosis . Among sequences specifically designed for higher magnetic fields, magnetization‐prepared two rapid acquisition gradient echoes (MP2RAGE) is a 3‐dimensional T1‐weighted sequence with strong contrast between gray and white matter and minimal effect of B1 inhomogeneity.…”

Functional brain imaging in neuropsychology over the past 25 years.

“…In the near future, systems of 12T and possibly even 20T (Budinger et al, 2016) will become available, offering the ability to visualize new features in resolution of about 0.1 millimeters (current 3T can capture about 1mm) (Budinger & Bird, 2017). Currently, use of 7T is well tolerated (Theysohn et al, 2008) and produces higher functional sensitivity in clinical studies, including pre-surgical planning (Beisteiner et al, 2011) as well as increased morphological specificity in Alzheimer’s disease (Nakada, Matsuzawa, Igarashi, Fujii, & Kwee, 2008), Parkinson’s disease (Cho et al, 2010), multiple sclerosis (Kollia et al, 2009; Metcalf et al, 2010), epilepsy (Veersema et al) and brain lesions (Moenninghoff et al, 2010; Tallantyre et al, 2009). Moreover, it will provide additional insight into neurotransmitter systems that are not easily resolved at lower field strengths (Cai et al, 2012; D.…”