Detecting focal cortical dysplasia lesions from FLAIR-negative images based on cortical thickness

Abstract

Background: Focal cortical dysplasia (FCD) is a neuronal migration disorder and is a major cause of drug-resistant epilepsy. However, many focal abnormalities remain undetected during routine visual inspection, and many patients with histologically confirmed FCD have normal fluid-attenuated inversion recovery (FLAIR-negative) images. The aim of this study was to quantitatively evaluate the changes in cortical thickness with magnetic resonance (MR) imaging of patients to identify FCD lesions from FLAIR-negative images. Methods: We first used the three-dimensional (3D) Laplace method to calculate the cortical thickness for individuals and obtained the cortical thickness mean image and cortical thickness standard deviation (SD) image based on all 32 healthy controls. Then, a cortical thickness extension map was computed by subtracting the cortical thickness mean image from the cortical thickness image of each patient and dividing the result by the cortical thickness SD image. Finally, clusters of voxels larger than three were defined as the FCD lesion area from the cortical thickness extension map. Results: The results showed that three of the four lesions that occurred in non-temporal areas were detected in three patients, but the detection failed in three patients with lesions that occurred in the temporal area. The quantitative analysis of the detected lesions in voxel-wise on images revealed the following: specificity (99.78%), accuracy (99.76%), recall (67.45%), precision (20.42%), Dice coefficient (30.01%), Youden index (67.23%) and area under the curve (AUC) (83.62%). Conclusion: Our studies demonstrate an effective method to localize lesions in nontemporal lobe regions. This novel method automatically detected FCD lesions using only FLAIR-negative images from patients and was based only on cortical thickness feature. The method is noninvasive and more effective than a visual analysis for helping doctors make a diagnosis.

Focal Cortical Dysplasia Type Ⅲ Related Medically Refractory Epilepsy: MRI Findings and Potential Predictors of Surgery Outcome

“…sequence, the cortical and subcortical hyper-signal is easier to detect [11,12]. Neuroimaging abnormalities have been reported in patients with FCD, such as expand/atrophic cortical, indistinctness of the gray-white matter junction, hyperintensity changes, etc., but most of these reports are from patients with FCD type Ⅰ and/or type Ⅱ.…”

“…Generally, MRI is the preferred imaging technique for detecting the structural basis of epilepsy [9,10]. In the T2W fluid-attenuated inversion recovery (T2W FLAIR) imaging sequence, the cortical and subcortical hyper-signal is easier to detect [11,12]. Neuroimaging abnormalities have been reported in patients with FCD, such as expand/atrophic cortical, indistinctness of the gray-white matter junction, hyperintensity changes, etc., but Diagnostics 2021, 11, 2225 2 of 11 most of these reports are from patients with FCD type I and/or type II.…”

Malformation of the Cortical Development Associated with Severe Clusters of Epileptic Seizures

“…FCD is classified in type I, II, and III depending on the morphology, the expression of the proteins and the association with other brain lesions [ 19 ]. Human MRI in FCD I usually shows no visible changes, while in FCD II, the focal cortical thickening, fuzziness between the gray and white matter, the white matter hyperintensity on T2 weighted images (T2WI) and fluid attenuated inversion recovery (FLAIR), the widened gyri, and abnormal sulci can be observed [ 20 ]. There are some available techniques used for the precise detection of the FCD lesions in human medicine, which show a good performance, mostly based on automated methods [ 20 ].…”

Improved detection of focal cortical dysplasia in normal‐appearing FLAIR images using a Bayesian classifier

“…Cortical thickness ranged from 1.5 to 4.5 mm 13 . Some studies have focused on cortical thickness to identify lesions 10,14,15 . Currently, the most commonly used cortical thickness measurement tools include Civet‐CLASP, 16,17 Free surfer, 18 and differential homeomorphisms 19 .…”

“…13 Some studies have focused on cortical thickness to identify lesions. 10,14,15 Currently, the most commonly used cortical thickness measurement tools include Civet-CLASP, 16,17 Free surfer, 18 and differential homeomorphisms. 19 A recent study used cortical thickness extracted from surface morphology as a feature to identify cortical lesions with up to 92% sensitivity and 96% specificity and successfully distinguished patients with FCD from those without.…”