Thin isotropic FLAIR MR images at 1.5T increase the yield of focal cortical dysplasia transmantle sign detection in frontal lobe epilepsy

Kokkinos, Vasileios; Kallifatidis, Alexandros; Kapsalaki, Eftychia Z.; Papanikolaou, Nikolaos; Garganis, Kyriakos

doi:10.1016/j.eplepsyres.2017.02.018

Cited by 14 publications

(9 citation statements)

References 46 publications

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“…The improved visualization of epileptogenic zones on FLAWS is primarily due to the following factors: (1) gray matter-specific contrast is suitable for displaying the predominant histopathological abnormalities in subtle epileptogenic zones, including altered cortical organization and cytological anomalies at the bottom of the sulcus ( Bernasconi et al, 2011 ; Blümcke et al, 2011 ). It is consistent with our results that the most common feature of FCD was “blurred junction of the gray-white matter;” (2) the 1-mm isotropic voxel size can increase the spatial resolution and reduce partial volume effects ( Kokkinos et al, 2017 ); (3) the epileptogenic zones at the bottom of the sulcus, which cannot be detected in the 2D images, can be displayed well by using multi-planar reformatting of 3D images. According to our results, some epileptogenic lesions, which cannot be identified on conventional MRI or even on 3D-FLAIR images, could be detected on the FLAWS images.…”

Section: Discussionsupporting

confidence: 90%

Gray-matter-specific MR imaging improves the detection of epileptogenic zones in focal cortical dysplasia: A new sequence called fluid and white matter suppression (FLAWS)

Chen

Qian

Kober

et al. 2018

NeuroImage: Clinical

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ObjectivesTo evaluate the diagnostic value and characteristic features of FCD epileptogenic zones using a novel sequence called fluid and white matter suppression (FLAWS).Materials and methodsThirty-nine patients with pathologically confirmed FCD and good surgery outcomes (class I or II, according to the Engel Epilepsy Surgery Outcome Scale) were retrospectively included in the study. All the patients underwent a preoperative whole-brain MRI examination that included conventional sequences (T2WI, T1WI, two-dimensional (2D) axial, coronal fluid-attenuated inversion recovery [FLAIR]) and FLAWS. An additional 3D-FLAIR MRI sequence was performed in 17 patients. To evaluate the sensitivity and specificity of FLAWS and investigate the cause of false-positives, 36 healthy volunteers were recruited as normal controls. Two radiologists evaluated all the image data. The detection rates of the FCD epileptogenic zone on different sequences were compared based on five criteria: abnormal cortical morphology (thickening, thinning, or abnormally deep sulcus); abnormal cortical signal intensity; blurred gray-white matter junction; abnormal signal intensity of the subcortical white matter, and the transmantle sign. The sensitivity and specificity of FLAWS for detecting the FCD lesions were calculated with the reviewers blinded to all the clinical information, i.e. to the patient identity and the location of the resected regions. To explore how many features were sufficient for the diagnosis of the epileptogenic zones, the frequency of each criterion in the resected regions and their combinations were assessed on FLAWS, according to the results of the assessment when the reviewers were aware of the location of the resected regions. Based on the findings of the 17 patients with an additional 3D-FLAIR scan when the reviewers were aware of the location of the resected regions, quantitative analysis of the regions of interest was used to compare the tissue contrast among 2D-axial FLAIR, 3D-FLAIR, and the FLAWS sequence. Visualization score analysis was used to evaluate the visualization of the five features on conventional, 3D-FLAIR, and FLAWS images. Finally, to explore the reason for false-positive results, a further evaluation of the whole brain FLAWS images was conducted for all the subjects.ResultsThe sensitivity and specificity for detecting the FCD lesions on the FLAWS sequence were 71.9% and 71.1%, respectively. When the reviewers were blinded to the location of the resected regions, the detection rate of the FLAWS sequence was significantly higher than that of the conventional sequences (P = 0.00). In the 17 patients who underwent an additional 3D FLAIR scan, no statistically significant difference was found between the FLAWS and the 3D-FLAIR (P = 0.25). All the patients had at least two imaging features, one of which was “the blurred junction of the gray-white matter.” The transmantle sign, which is widely believed to be a specific feature of FCD type II, could also be observed in type I on the FLAWS sequence. The relative ti...

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Section: Discussionsupporting

confidence: 90%

Gray-matter-specific MR imaging improves the detection of epileptogenic zones in focal cortical dysplasia: A new sequence called fluid and white matter suppression (FLAWS)

Chen

Qian

Kober

et al. 2018

NeuroImage: Clinical

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“…The cortical tubers also show MR imaging findings, known as the radially oriented white matter band, that are similar to the TMS of FCD type IIb. [27][28][29] Magnetization transfer contrast is a technique for improving image contrast in MR imaging, based on the difference in magnetic field-induced frequencies between mobile free water protons and macromolecular bound protons. 26,30 Pinto Gama et al 25 noted that the density of cells and calcium deposition may also play a role by causing shortening of the water T1, leading to a decrease in the effectiveness of signal suppression by magnetization transfer contrast.…”

Section: Discussionmentioning

confidence: 99%

Radiologic and Pathologic Features of the Transmantle Sign in Focal Cortical Dysplasia: The T1 Signal Is Useful for Differentiating Subtypes

Kimura

Shioya

Saito³

et al. 2019

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE: The transmantle sign is a characteristic MR imaging finding often seen in focal cortical dysplasia type IIb. The transmantle sign is typically hyperintense on T2WI and FLAIR and hypointense on T1WI. However, in some cases, it shows T1 high signal. We evaluated the imaging and pathologic findings to identify the causes of the T1 high signal in the transmantle sign. MATERIALS AND METHODS: We retrospectively reviewed the preoperative imaging data of 141 consecutive patients with histologically proved focal cortical dysplasia. We selected 25 patients with focal cortical dysplasia with the transmantle sign and divided them into groups based on the pathologic focal cortical dysplasia subtype and T1 signal of the transmantle sign. We evaluated the clinical, radiologic, and pathologic findings, including the number of balloon cells and dysmorphic neurons and the severity of gliosis or calcifications and compared them among the groups. RESULTS: Nine of the 25 patients had a T1-high-signal transmantle sign; the other 16 patients did not. All 9 patients with a T1-high-signal transmantle sign were diagnosed as type IIb (group A). Of the 16 patients with no T1-high-signal transmantle sign, 13 were diagnosed as having type IIb (group B), and the other 3 patients, as type IIa (group C). The number of balloon cells was significantly higher in group A than in the other groups, but there were no differences regarding dysmorphic neurons, the severity of gliosis, or calcifications. CONCLUSIONS: Approximately 6% (9/141) of this patient series had a T1-high-signal transmantle sign, and all were type IIb. The signal may reflect a rich density of balloon cells. This finding could support the differentiation of subtypes, especially type IIb.

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“…Relying on a written radiological report may be insufficient, as putative anomalies may have been overlooked due to poor image quality or lack of the reader's expertise in neuroimaging of epilepsy. 12 It is thus utterly important to repeat the examination with an optimized protocol, 48 particularly in patients with drug-resistant epilepsy and previous "normal" MRI, as this may reveal a lesion in 30%-65% of cases [49][50][51] ; when MRI is combined with image postprocessing, sensitivity may be as high as 70%, 52 thereby significantly improving clinical decision making. Given the evidence for progressive brain atrophy developing over 1-3 years in both patients with refractory and patients with well-controlled seizures, 37,44-46 repeated MRI may have prognostic value.…”

Section: The Importance Of Repeating the Mrimentioning

confidence: 99%

“…44,47 Finally, the diagnostic yield depends heavily upon logistics, including image resolution, magnetic field strength, number of phased-array head coils, and expertise of the reader. 12 It is thus utterly important to repeat the examination with an optimized protocol, 48 particularly in patients with drug-resistant epilepsy and previous "normal" MRI, as this may reveal a lesion in 30%-65% of cases [49][50][51] ; when MRI is combined with image postprocessing, sensitivity may be as high as 70%, 52 thereby significantly improving clinical decision making. Notably, imaging in the first year of life may be helpful in identifying FCD associated with very subtle signal changes on later images of the postmyelinated, matured brain and should be retained for comparison.…”

Section: The Importance Of Repeating the Mrimentioning

confidence: 99%

Recommendations for the use of structural magnetic resonance imaging in the care of patients with epilepsy: A consensus report from the International League Against Epilepsy Neuroimaging Task Force

et al. 2019

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Structural magnetic resonance imaging (MRI) is of fundamental importance to the diagnosis and treatment of epilepsy, particularly when surgery is being considered. Despite previous recommendations and guidelines, practices for the use of MRI are variable worldwide and may not harness the full potential of recent technological advances for the benefit of people with epilepsy. The International League Against Epilepsy Diagnostic Methods Commission has thus charged the 2013‐2017 Neuroimaging Task Force to develop a set of recommendations addressing the following questions: (1) Who should have an MRI? (2) What are the minimum requirements for an MRI epilepsy protocol? (3) How should magnetic resonance (MR) images be evaluated? (4) How to optimize lesion detection? These recommendations target clinicians in established epilepsy centers and neurologists in general/district hospitals. They endorse routine structural imaging in new onset generalized and focal epilepsy alike and describe the range of situations when detailed assessment is indicated. The Neuroimaging Task Force identified a set of sequences, with three‐dimensional acquisitions at its core, the harmonized neuroimaging of epilepsy structural sequences—HARNESS‐MRI protocol. As these sequences are available on most MR scanners, the HARNESS‐MRI protocol is generalizable, regardless of the clinical setting and country. The Neuroimaging Task Force also endorses the use of computer‐aided image postprocessing methods to provide an objective account of an individual's brain anatomy and pathology. By discussing the breadth and depth of scope of MRI, this report emphasizes the unique role of this noninvasive investigation in the care of people with epilepsy.

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Thin isotropic FLAIR MR images at 1.5T increase the yield of focal cortical dysplasia transmantle sign detection in frontal lobe epilepsy

Cited by 14 publications

References 46 publications

Gray-matter-specific MR imaging improves the detection of epileptogenic zones in focal cortical dysplasia: A new sequence called fluid and white matter suppression (FLAWS)

Gray-matter-specific MR imaging improves the detection of epileptogenic zones in focal cortical dysplasia: A new sequence called fluid and white matter suppression (FLAWS)

Radiologic and Pathologic Features of the Transmantle Sign in Focal Cortical Dysplasia: The T1 Signal Is Useful for Differentiating Subtypes

Recommendations for the use of structural magnetic resonance imaging in the care of patients with epilepsy: A consensus report from the International League Against Epilepsy Neuroimaging Task Force

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