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Purpose Focal cortical dysplasias (FCD) type IIb and cortical tubers in tuberous sclerosis complex (TSC) are histopathologically similar and are both epileptogenic lesions frequently causing pharmacoresistant epilepsies. Morphometric analysis of T1- and T2-weighted MRI volume data sets can enhance visualization of FCD. Here, we retrospectively investigated whether morphometric MRI analysis is of equal benefit for visualizing cortical tubers. Materials and methods Morphometric analysis was applied to T1- and partly also T2-weighted 1.5T or 3T MRI volume data sets of 15 TSC patients using a fully automated MATLAB ® script (i.e. MAP07) commonly used for FCD detection. In this study, focus was on the most sensitive of the resulting morphometric feature maps (i.e. the ‘junction image') which highlights blurring of the gray–white matter junction in comparison to a normal database. The visualization of tubers in these ‘junction images' was quantitatively compared with that in conventional MR sequences. Results In all patients, morphometric analysis visualized almost all tubers detected in the normal MRI, and additionally highlighted on average 23% (range 3–50%) more tubers which were not detected by visual analysis of the conventional MR sequences. When T2 volume data sets from a 3T scanner were available for postprocessing, the rate of additionally detected tubers increased to 29% on average. These formerly overlooked tubers were usually smaller than the tubers already found in the conventional MRI. Conclusion Morphometric analysis of MRIs in TSC can highlight cortical tubers which are likely to be overlooked in conventional MRI sequences alone. Additionally detected tubers may be of potential importance for both presurgical evaluation and initial diagnosis of TSC.

Summary Purpose To describe and evaluate a novel MRI post-processing technique for automated quantitative hippocampal FLAIR analysis in patients with hippocampal sclerosis (HS). Patients and methods Based on a method for FLAIR analysis presented by Focke et al. (2009) , T1 and coregistered FLAIR scans of individual subjects were processed together in SPM5 to conduct both a spatial and an intensity normalization of the FLAIR scans. In a further development described here, the resulting normalized FLAIR images were thresholded and weighted by a probabilistic hippocampal mask to determine the average FLAIR intensities of left and right hippocampus. The method was applied to the MRI data of 103 HS patients and 131 controls. Using a 95% confidence region calculated from the FLAIR intensities of controls as threshold, the performance in discriminating both groups was assessed. Results One hundred of 103 patients and among those all 23 patients with histologically confirmed HS fell outside the 95% confidence region, amounting to 97.1% sensitivity. All but 6 controls (=95.4%) were found within the confidence region, corresponding to the expected specificity. The method could also distinguish bilateral HS and visualize signal changes after status epilepticus. Conclusion Automated FLAIR analysis is a promising tool to quantify hippocampal signal alterations, to support the detection of HS, and to monitor the temporal evolution of the disease.

Summary Purpose Focal cortical dysplasias (FCD) are highly epileptogenic lesions frequently accounting for pharmaco-resistant focal epilepsy. Visual MRI analysis combined with morphometric analysis of T1-weighted MRI data was shown to be of higher diagnostic sensitivity in detecting and delineating FCD than conventional visual analysis alone. Here we investigate whether morphometric analysis of T2-weighted MRI volume data sets is of equal benefit or perhaps more helpful for visualizing FCD. Materials and methods Morphometric analysis was applied to T1- and T2-weighted MRI volume data sets of 20 epilepsy patients with FCD using a fully automated MATLAB script with scanner- and sequence-specific normal databases for T1 and T2 images. For each modality, a new feature map (i.e., ‘junction image') highlighting the FCD-typical blurring of the gray–white matter junction and quantifying this feature in comparison to the normal database in terms of z -scores was calculated. The resulting T1 and T2 ‘junction images' were compared for conspicuity and recognizability of the FCD both qualitatively by visual assessment and quantitatively by analysis of the mean z -scores inside and outside the lesions. Results In 80% of the cases, the FCD presented with higher contrast and/or clearer delineation in the T2 than in the T1 ‘junction images' and were thus easier to recognize in these images. The quantitative analysis supported this impression: in 95% of cases, the ratio of mean z -scores inside and outside the FCD was higher in T2- than in T1-based ‘junction images'. For the T2 ‘junction images', this ratio amounted to 8.7 on average and was thus more than twice as high as the corresponding T1 result of 3.7 ( p Conclusion Concerning visualization of FCD by highlighting blurring of the gray–white matter junction, the results of the present study indicate that morphometric analysis of T2-weighted MRI data on average is superior to T1-based morphometry.

Purpose Focal cortical dysplasia (FCD), a frequent cause of partial epilepsy, is often associated with blurring of the gray–white matter junction in magnetic resonance images (MRI). To improve the recognition and delineation of FCD we developed a novel voxel-based image post-processing method for enhanced visualization of blurred gray–white matter junctions. Methods Using standard algorithms of statistical parametric mapping software (SPM99) a T1-weighted MRI volume data set is normalized and segmented. The distribution of gray and white matter is analyzed on a voxelwise basis and compared with a normal database. Based on this analysis, a three-dimensional feature map is created which highlights brain areas with blurred gray–white matter transition. This method was applied to the MRI data of 25 epilepsy patients with histologically proven FCD. Results In 18/25 patients the new feature maps clearly showed that the dysplastic lesions were accompanied by blurring of the gray–white matter junction. Combined with a formerly published method of voxel-based 3D MRI analysis, 21/25 FCD lesions were shown to be associated with either blurring or abnormal extension of gray matter beyond the normal cortical ribbon, including four cases with lesions not or incompletely recognized on conventional MRI. Conclusions The MRI post-processing presented here improves the visualization of FCD and may increase the diagnostic yield of MRI. Thereby, it provides a valuable additional diagnostic tool in the presurgical evaluation of epilepsy patients.