Lakshmichand T. Kishore, MD, MBBS, DMRD

Intravenous iodinated contrast agents are generally safe. Though the frequency of side effects has fallen significantly since the introduction of nonionic, monomeric contrast agents,1 however, side effects remain an important issue.

Any fluid-filled cavity or sac that is lined by an epithelium is a cyst, and intracranial cystic lesions are a common finding on CT and MR imaging of the brain.1,2 These lesions contain either cerebrospinal fluid, fluid that is similar to CSF, mucus, or proteinaceous fluid. They are lined by epithelial cells, inflammatory cells, or glial cells. The attenuation characteristics of the cyst on CT and MRI and the contrast enhancement patterns depend on the cyst's contents and the composition of the wall.