FRACTAL DESCRIPTION OF CEREBRAL CORTICAL PATTERNS IN FRONTAL-LOBE EPILEPSY

The convoluted pattern of normal cerebral cortex resists description b y Euclidean geometry. However, subtle abnormalities often unrecognised in vivo may underlie a wide range of neurological disorders. Abnormal ities of cortical morphology frequently characterise these lesions, an d we applied fractal geometry in an attempt to quantify these abnormal ities. We have demonstrated typical fractal scaling properties for the cortical-white matter interface on axial and coronal MR images, with a fractal dimension (D-f) of 1.45 + 0.06 (mean + 1 standard deviation) in normal subjects. We have also applied this to 16 patients with fro ntal lobe epilepsy, a condition associated with subtle disruptions of the cortical ribbon, all of whom had no obvious abnormality on visual inspection of the images. Nine of these 16 had a D-f <1.27 (mean -3 st andard deviations). A control group of 10 patients with temporal lobe epilepsy with a focal foreign tissue lesion (vascular or tumoural) all had D-f in the normal range. Analysis of shape using this method iden tifies subtle abnormalities of the cortical ribbon, and has potential application to images of the human brain in a wide range of clinical a nd pathophysiological settings.