Ultra-High-Field MR Imaging in Polymicrogyria and Epilepsy

Ciantis, Alessio De; Barkovich, A. James; Cosottini, Mirco; Barba, Carmen; Montanaro, Domenico; Costagli, Mauro; Tosetti, Michela; Biagi, Laura; Dobyns, William B.; Guerrini, Renzo

doi:10.3174/ajnr.a4116

Cited by 101 publications

(58 citation statements)

References 60 publications

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“…The added diagnostic value of 7T, compared to lower field strengths, has been demonstrated for polymicrogyria, 28 vascular malformations, 29 hippocampal sclerosis, 30 brain tumors, 31 stroke, 32 multiple sclerosis, 33 and degenerative brain diseases. 34 However, no studies using a field strength of 7T have addressed its Of note, D, and its magnified image E show normal distinction between white and gray matter in the right superior temporal gyrus and the insula.…”

Section: Discussionmentioning

confidence: 99%

7TMRIin focal epilepsy with unrevealing conventional field strength imaging

Ciantis

Barba

Tassi³

et al. 2016

Epilepsia

137

127

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SUMMARYObjective: To assess the diagnostic yield of 7T magnetic resonance imaging (MRI) in detecting and characterizing structural lesions in patients with intractable focal epilepsy and unrevealing conventional (1.5 or 3T) MRI. Methods: We conducted an observational clinical imaging study on 21 patients (17 adults and 4 children) with intractable focal epilepsy, exhibiting clinical and electroencephalographic features consistent with a single seizure-onset zone (SOZ) and unrevealing conventional MRI. Patients were enrolled at two tertiary epilepsy surgery centers and imaged at 7T, including whole brain (three-dimensional [3D] T 1 -weighted [T1W] fast-spoiled gradient echo (FSPGR), 3D susceptibility-weighted angiography [SWAN], 3D fluid-attenuated inversion recovery [FLAIR]) and targeted imaging (2D T 2 *-weighted dual-echo gradient-recalled echo [GRE] and 2D gray-white matter tissue border enhancement [TBE] fast spin echo inversion recovery [FSE-IR]). MRI studies at 1.5 or 3T deemed unrevealing at the referral center were reviewed by three experts in epilepsy imaging. Reviewers were provided information regarding the suspected localization of the SOZ. The same team subsequently reviewed 7T images. Agreement in imaging interpretation was reached through consensus-based discussions based on visual identification of structural abnormalities and their likely correlation with clinical and electrographic data. Results: 7T MRI revealed structural lesions in 6 (29%) of 21 patients. The diagnostic gain in detection was obtained using GRE and FLAIR images. Four of the six patients with abnormal 7T underwent epilepsy surgery. Histopathology revealed focal cortical dysplasia (FCD) in all. In the remaining 15 patients (71%), 7T MRI remained unrevealing; 4 of the patients underwent epilepsy surgery and histopathologic evaluation revealed gliosis. Significance: 7T MRI improves detection of epileptogenic FCD that is not visible at conventional field strengths. A dedicated protocol including whole brain FLAIR and GRE images at 7T targeted at the suspected SOZ increases the diagnostic yield.

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Section: Discussionmentioning

confidence: 99%

7TMRIin focal epilepsy with unrevealing conventional field strength imaging

Ciantis

Barba

Tassi³

et al. 2016

Epilepsia

137

127

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“…For this reason, polymicrogyria is frequently misdiagnosed as pachygyria or LIS. With use of high-field or ultra-high-field strength MRI with appropriate age-specific protocols, polymicrogyria can be reliably differentiated -especially the classic form of polymicrogyria with perisylvian location, schizencephaly, and several other forms -from other cortical malformations and its extent fully recognized [De Ciantis et al, 2015]. The imaging appearance of polymicrogyria varies with the patient's age.…”

Section: Brain Imagingmentioning

confidence: 99%

Genetic Basis of Brain Malformations

et al. 2016

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Malformations of cortical development (MCD) represent a major cause of developmental disabilities, severe epilepsy, and reproductive disadvantage. Genes that have been associated to MCD are mainly involved in cell proliferation and specification, neuronal migration, and late cortical organization. Lissencephaly-pachygyria-severe band heterotopia are diffuse neuronal migration disorders causing severe global neurological impairment. Abnormalities of the LIS1, DCX, ARX, RELN, VLDLR, ACTB, ACTG1, TUBG1, KIF5C, KIF2A, and CDK5 genes have been associated with these malformations. More recent studies have also established a relationship between lissencephaly, with or without associated microcephaly, corpus callosum dysgenesis as well as cerebellar hypoplasia, and at times, a morphological pattern consistent with polymicrogyria with mutations of several genes (TUBA1A, TUBA8, TUBB, TUBB2B, TUBB3, and DYNC1H1), regulating the synthesis and function of microtubule and centrosome key components and hence defined as tubulinopathies. MCD only affecting subsets of neurons, such as mild subcortical band heterotopia and periventricular heterotopia, have been associated with abnormalities of the DCX, FLN1A, and ARFGEF2 genes and cause neurological and cognitive impairment that vary from severe to mild deficits. Polymicrogyria results from abnormal late cortical organization and is inconstantly associated with abnormal neuronal migration. Localized polymicrogyria has been associated with anatomo-specific deficits, including disorders of language and higher cognition. Polymicrogyria is genetically heterogeneous, and only in a small minority of patients, a definite genetic cause has been identified. Megalencephaly with normal cortex or polymicrogyria by MRI imaging, hemimegalencephaly and focal cortical dysplasia can all result from mutations in genes of the PI3K-AKT-mTOR pathway. Postzygotic mutations have been described for most MCD and can be limited to the dysplastic tissue in the less diffuse forms.

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“…It is conceivable that the increased signal-to-noise and contrast-to-noise ratio and spatial resolution provided by ultra-high-field (7T) MRI could increase the conspicuity of FCD lesions [48,49]. This will also provide the basis for more accurate histopathological correlative studies [50-52].…”

Section: Future Directionsmentioning

confidence: 99%

MRI postprocessing in presurgical evaluation

Wang

Alexopoulos

2016

Current Opinion in Neurology

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Purpose of Review Advanced MRI post-processing techniques are increasingly used to complement visual analysis and elucidate structural epileptogenic lesions. This review summarizes recent developments in MRI post-processing in the context of epilepsy pre-surgical evaluation, with the focus on patients with unremarkable MRI by visual analysis (i.e., “nonlesional” MRI). Recent Findings Various methods of MRI post-processing have been reported to show additional clinical values in the following areas: (1) lesion detection on an individual level; (2) lesion confirmation for reducing the risk of over reading the MRI; (3) detection of sulcal/gyral morphologic changes that are particularly difficult for visual analysis; and (4) delineation of cortical abnormalities extending beyond the visible lesion. Future directions to improve performance of MRI post-processing include using higher magnetic field strength for better signal and contrast to noise ratio, adopting a multi-contrast frame work, and integration with other noninvasive modalities. Summary MRI post-processing can provide essential value to increase the yield of structural MRI and should be included as part of the presurgical evaluation of nonlesional epilepsies. MRI post-processing allows for more accurate identification/delineation of cortical abnormalities, which should then be more confidently targeted and mapped.

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Ultra-High-Field MR Imaging in Polymicrogyria and Epilepsy

Cited by 101 publications

References 60 publications

7TMRIin focal epilepsy with unrevealing conventional field strength imaging

7TMRIin focal epilepsy with unrevealing conventional field strength imaging

Genetic Basis of Brain Malformations

MRI postprocessing in presurgical evaluation

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