Sinus CT scan results - what to expect?

I am not entirely sure which specific "cavity" you are referring to—when looking at a sinus scan, one has to analyze the maxillary, sphenoid, frontal, and ethmoid sinuses (which is quite a collection of "cavities," wouldn't you say?)
Even if one sinus appears more aerated than its counterpart on the image, that might simply be due to how you were positioned during the scan or perhaps just the unique shape of your bone structure—it doesn't necessarily mean there is an issue with drainage. That is precisely why these scans are ordered—to shed light on those exact variables.

So, unfortunately... yes, it is impossible to give you a definitive answer to your question without seeing the actual imaging.

My MRI results
"There is marginal thickening of the mucosa in the maxillary, ethmoid, and frontal sinuses."

Does "marginal" mean just a little? Is it not much?
And does "marginal" mean it's only along the edges, leaving the center clear?

Thanks