Machine learning to detect brain lesions in focal epilepsy

Abstract

<strong>PURPOSE:</strong> Identifying areas of abnormality on MRI brain scans in individuals with focal epilepsy is funda- mental to the diagnosis and treatment of the condition. However, in about a third of patients with focal epilepsy, brain scans appear to be normal (MRI-negative) as human observers cannot detect any abnormality with cur- rent imaging technology. The objective of this paper is to provide a novel approach in presenting localization using machine learning in order to locate areas of abnormality on patients with focal epilepsy on a per-voxel basis by comparing them with healthy controls. As a proof-of-concept, the technique is first applied to patients with visible lesions providing a ground truth (MRI-positive), but future work will extend this to MRI-negative subjects. <strong>METHODS:</strong> Our data consists of multi-modal brain MR images from 62 healthy control subjects and 44 MRI- positive patients with focal epilepsy. We utilized a support vector machine (SVM) as our probabilistic classifier and train it with two classes of data. We generate probability maps applying our machine learning classifier on all voxels of a test subjects to visualize the predictions. Overlap scores are used to evaluate the classifier performance in MRI-positive patients. <strong>RESULTS:</strong> Our model reached 83% specificity, 91% sensitivity, and an Area Under the Curve (AUC) of 0.896 for the task of voxel-based classification of normal versus abnormal voxels. In addition, Dice scores of up to 0.66 were achieved for the overlap measure of lesion probability map and the ground truth labels annotated by a neurologist. <strong>CONCLUSION:</strong> We demonstrated a novel approach in presenting localization using machine learning tech- niques to localize focal epilepsy lesions from multi-modal MR images.