As a first stage, we selected all nodes in the top 1% of the projection onto the FCD unit vector, then retained all clusters containing 5 or more nodes.
For each surviving cluster, we computed the mean cluster , calculated as area \(\times\)mean FCD probability, as well as the cluster's rank among surviving clusters in that subject.
Statistical Analysis
All statistical analysis was carried out using XXX. For the logistic regression feature prediction models, performance was evaluated for each model using the coefficient of determination \(r{^2}\); effect size was reported as in \cite{cohen1988statistical}: \(r=0.1\) as small, \(r=0.3\) as medium, and \(r=0.5\) as large. For each distance-wise comparison between patches, Welch's t-test was used to estimate the effect size of the differences, reported as in \cite{cohen1988statistical}: \(d=0.2\) as small , \(d=0.5\) as medium, and \(d=0.5\) as large.
Sensitivity of each classifier was assessed initially for MRI+ patients and then for all patients. We calculated a receiver operating characteristics (ROC) curve and area under the curve (AUC). True positives were defined as MRI+ patients with co-localization of a detected cluster and the manual lesion mask, and for MRI- patients, as overlap of a detected cluster with the resection mask. False positives were defined as HVs with detected clusters detected above a given threshold. The optimal threshold to apply to the resulting clusters for each method was determined using the Youden Index (calculated as sensitivity + specificity - 1 for each threshold). Lesion detection and number of extralesional clusters (outside of the lesion or resection masks or in HVs) were assessed for all patients and HVs individually.
Results
Study Participants
A total of 15 patients with drug resistant focal epilepsy and FCD (median age 27, range 15-53, 11 females) and 30 healthy controls (median age 23, range 8-63, 12 females) were included in this study. FCDs were identified in the radiological reports in 6/15 patients, an additional 5 patients had lesions identifiable on post-hoc analysis (MRI+ n=11). See Table 1 for further details.