Diagnosis of subtle focal dysplastic lesions: Curvilinear reformatting from three-dimensional magnetic resonance imaging

Focal cortical dysplasia is a frequent cause of medically intractable parti al epilepsy. These lesions are being increasingly identified by high qualit y images provided by magnetic resonance imaging (MRI), resulting in improve d seizure control of surgically treated patients. Small dysplastic lesions are often missed by conventional MRI methods. The identification of subtle structural abnormalities by rectilinear slices is often limited by the comp lex convolutional pattern of the brain. We dec-eloped a method of curviline ar reformatting of three-dimensional MRI data that improves the anatomical display of the gyral structure of the hemispheric convexities. It also redu ces the asymmetric sampling of gray-white matter that may lead to false-pos itive results. We present 5 patients in whom conventional two-dimensional a nd three-dimensional MRI with multiplanar reformatting was initially consid ered normal. Subsequent studies using curvilinear reformatting identified l esions in all. Four patients underwent surgery with histological diagnosis of focal cortical dysplasia. Three patients are seizure-free and 1 had sign ificant improvement in seizure control. These results indicate that an incr ease in the detection of subtle focal dysplastic lesions may be accomplishe d when one improves the anatomical display of the brain gyral structure by performing curvilinear reformatting.