Disclaimer: This is the world of the radiologist and the neurologist. Obviously trust them if something like this has come up on a family member’s imaging. They will put their heads together with your internist to decide what’s next.

This review applies to the unfortunate patient who has just found out that there is a ring lesion showing up on their “CT” or MRI. Since the scope of this website is starting to circle the globe well beyond the US and Canada, I’ll cover the important possibilities here and elsewhere.
These are the important things that your physician has memorized to be your advocate should such a finding come up on your radiographic imaging.


There are three general groups of people that present with ring enhanced lesions in their brain as per CT or MRI.

  1. If someone presents who is elderly, has a fever, has a sinus infection, and there has been some sort of history of a procedure, surgical or interventional or otherwise, in their head, then the most likely thing they have is a brain abscess.
  2. If the patient is in a Third World country or has traveled to a Third World country and has returned back to the US or Canada, and has a seizure which represents their first seizure ever, then this is most likely to be caused by neurocysticercosis. This is a condition produced by a tapeworm that’s found in pork. This may be ingested by mouth directly. Or the exposure might be as a result of bad hygiene because pigs live in the waters of Third World countries, and that expose the eggs of the tapeworm to the water in which people bathe or drink.
  3. The third presentation of a ring in enhanced lesion in the brain as per CT or MRI is in the HIV patient. AIDS patients, when their CD4 (a lymphocyte count which guides there well being and care) falls to a critical level, are highly at risk for developing toxoplasmosis. This is a bug that is found in cat feces and raw meat. It doesn’t bother people that aren’t immunocompromised. But it’s devastating to a patient with AIDS, again, with particularly low CD4 counts, or unborn babies, or the particularly elderly. All of these are immunocompromised hosts suitable for toxoplasmosis to hurt.


Three main presentations of patients with ring enhanced lesions in radiographic imaging like CT and MRI:
Old, Fever, sinusitis, procedure: brain abscess.3rd world, 1st seizure: neurocysticercosis (<- a tapeworm found in pig; oral intake or bad hygiene).HIV: toxoplasmosis (cat feces, raw meat).
In many of these presentations, neurosurgery is there next step to remove these brain lesions. The outcome is extremely variable. These are very unfortunate patients.