FOCAL CORTICAL DYSPLASIA - APPEARANCE OF MR-IMAGES

PURPOSE: To clarify the magnetic resonance (MR) imaging characteristic s of focal cortical dysplasia (FCD). MATERIALS AND METHODS: The author s reviewed the MR images of 14 patients with FCD, which was confirmed with histologic examination. RESULTS: MR images exhibited FCD in 13 of the 14 patients. All lesions were localized to part of one hemisphere . T2-weighted images showed blurring of the gray matter-white matter j unction and abnormal signal intensity in the white matter in 11 patien ts. T1-weighted images showed blurring of the gray matter-white matter junction in seven patients, broad gyri in nine, thick cortices in nin e, abnormal sulci in 10, and focal enlargement of the overlying subara chnoid space or adjacent ventricle in eight. Surgical specimens exhibi ted disruption of cortical lamination without abnormal gyration in all patients, cytomegalic neurons in the cortex in three, disorganized bi zarre glial cells in the cortex in seven, ectopic neurons or bizarre g lial cells in the white matter in nine, and blurring of the gray matte r-white matter junction in one. CONCLUSION: Blurring of the gray matte r-white matter junction with abnormal signal intensity in the white ma tter on T2-weighted images is characteristic of FCD. The presence of e ctopic neurons and bizarre glial cells, dysmyelination, and a reductio n in the number of myelinated fibers might have been responsible for t he MR imaging characteristics.