Gray-white differentiation is indistinct and overall signal is increased in the left cerebral hemisphere, with relative lack of sulcation in the left parietal region.
Generalized atrophy is present on the right.
A diffuse glioma could have a similar appearance, but a higher signal intensity would be expected, and the abnormal sulcation would be unexplained. Hemimegalencephaly represents a diffuse migrational anomaly involving an entire cerebral hemisphere. The parenchyma is disorganized, with hamartomatous proliferation, white matter abnormalities, and heterotopic gray matter. The cortex may be calcified and dysplastic. Patients with this anomaly typically have intractible seizures, and may require hemispherectomy.