Unusual symmetrical structures in brain CT — looking for medical explanations

Hi, I recently had a head CT done for unrelated medical reasons, and while looking at the images I noticed two small, symmetrical, ring-shaped areas in my brain, one on each side. I showed them to a couple of people I know in the medical field, but none of them had a definite explanation.
I’m not a radiologist, so I might just be misunderstanding what I’m seeing, but I haven’t been able to find anything online that looks quite the same. I’d be interested in hearing if anyone here has seen something similar in CT scans, or knows what these kinds of symmetrical patterns might indicate.