Table 1.
Demographic data of patients and controls.
Fig 1.
Flowchart of the sulcus-based analysis.
A) Processing steps for the controls. First, based on T1-weighted MRI (T1w MRI), cortical sulci were extracted. They were then automatically labeled (one color per label). The sulcus energy maps derived from this recognition process were then generated (blue to red colors, reflecting a sulcus pattern with a good match to the learning database and a bad match, respectively). These maps were averaged to obtain mean and standard deviation (SD) maps. B) Processing steps for a single FCD patient. Cortical sulci extraction, labeling, and generation of sulcus energy map were done as described in A. Finally, a sulcus energy z-score map was computed by dividing the difference between the sulcus energy of the patient and the mean sulcus energy of controls by the standard deviation of controls (blue to red colors, reflecting an increasing z-score).
Fig 2.
Visual identification of FCD sulci in a MR+ patient.
The hyperintensities in FLAIR (A) and the slight cortical thickening visible in T1 MRI (B) allowed to locate the lesion in the depth of an ascending branch of the left central sulcus (white arrows), at the intersection of the main branch of the central sulcus. These two sulci are automatically labeled (C): « superior branch of the pre-central sulcus» (orange) and « central sulcus » (red) and considered as FCD sulci.
Fig 3.
Sulci of the left central area, based on BrainVisa nomenclature (http://brainvisa.info), lateral (A) and medial (B) views: The central sulcus (S.C.) is surrounded by the superior postcentral sulcus (S.Po.C.sup), the retrocentral transverse ramus of the lateral fissure (F.C.L.r.retroC.tr), the inferior postcentral ramus of the intraparietal sulcus (F.I.P.Po.C.inf), the median frontal sulcus (S.F.median) and the median (S.Pe.C.median), marginal (S.Pe.C.marginal), superior (S.Pe.C.sup.), intermediate (S.Pe.C.inter.) and inferior (S.Pe.C.inf.) branches of the pre-central sulcus.
The ramifications of the central sulcus were composed of the central sylvian sulcus (S.C.sylvian), the paracentral lobule (S.C.LPC.) and the paracentral sulcus (S.p.C). Right hemisphere not shown.
Table 2.
List of FCD sulci for each patient.
Table 3.
Demographic data of MR+ and MR- patient subgroups.
Fig 4.
Illustrative examples of patients with maximum z-scores pointing to an FCD sulcus.
Z-score maps superimposed on gray–white matter interface surface models. For each patient, a color palette from blue to red was adjusted to the maximum z-score. Black arrow indicated the lesion. In Case 1, the maximum z-score (z = 3.4) pointed exactly to the FCD (red blob, arrow), in the depth of an ascending branch of the left central sulcus. In Case 2, the lesion was located on the right marginal precentral sulcus, which had a maximum z-score of 1.52. Of note, the right superior precentral sulcus (in red) also had a high, albeit not maximum, z-score (1.49). In Cases 3 and 4, the maximum z-scores (z = 2 and 0.4 respectively) pointed to the FCD sulcus, which stood-out from the neighboring sulci with much lower z-scores. In Case 5, the maximum z-score (z = 2.6) pointed to an FCD sulcus but there were other sulci with high local z-score beyond the FCD. In Case 6, even if the FCD was associated with a maximum z-score (z = 7.6), this high energy sulcus had a wide spatial extent, beyond the site of FCD.
Fig 5.
Sensitivity and specificity for quantitatively derived abnormal sulci compared with FCD sulci.