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)

Abstract

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...

Focal Cortical Dysplasia in Pediatric Epilepsy

“…This MP2RAGE can be a suitable sequence to delineate the lesion with high gray-white matter contrast, such as FCD [60]. A new sequence called fluid and white matter suppression (FLAWS) has been reported to be useful for the detection of FCD EZs [61]. FLAWS sequence acquires two images of 3D high spatial resolution images with white-matter signal suppression and cerebrospinal fluid (CSF) signal suppression.…”

High‐resolution multi‐T1–weighted contrast and T1 mapping with low sensitivity using the fluid and white matter suppression (FLAWS) sequence at 7T

“…This GM‐specific contrast is similar in purpose to the T 2 ‐weighted double‐inversion recovery contrast, 11 which is used to detect WM and intracortical lesions in multiple sclerosis 12 . These FLAWS properties suggest that this sequence has potential for the detection and segmentation of brain lesions 8,13,14 . The FLAWS sequence has also been shown to be of interest to visualize basal ganglia structures 15,16 and to perform brain tissue segmentation 17 …”

“…12 These FLAWS properties suggest that this sequence has potential for the detection and segmentation of brain lesions. 8,13,14 The FLAWS sequence has also been shown to be of interest to visualize basal ganglia structures 15,16 and to perform brain tissue segmentation. 17 Despite the potential clinical interest provided by the FLAWS sequence, its use has been limited for 7T imaging as it could not provide a bias-reduced T 1 -weighted image and its associated T 1 map.…”

Fluid and White Matter Suppression Imaging and Voxel-Based Morphometric Analysis in Conventional Magnetic Resonance Imaging-Negative Epilepsy

“…However, reports of FLAWS in epilepsy are rare because of its novelty. In a pilot study, we found that FLAWS was superior to conventional MRI sequences [T1, T2, and fluid-attenuated inversion recovery (FLAIR)] in visually identifying epileptic lesions among patients with both MRI-positive and MRI-negative focal cortical dysplasia (FCD) ( 8 ).…”