There are many causes of ring-enhancing lesions. Abscesses usually have smooth and thin rims, with restricted diffusion, and lots of surrounding vasogenic edema. Necrotic neoplasms (GBM, mets) often have thick and irregular rims with increased central diffusion - also with vasogenic edema. Fluid-secreting tumors, usually low-grade pilocytic astrocytoma or hemangioblastoma) have a nodule or only a partial rim of wall enhancement. Tumefactive demyelinating lesions (TDL) often have an incomplete rim usually without surrounding vasogenic edema.
20 авг 2013
