In some cases, the findings might include complete or subtotal sinus opacification, generalized or localized mucosal thickening, and the formation of gas-fluid levels, which
[radiopaedia.org]
Comparable with the findings described above, these include mucosal thickening, fluid levels, polypoid masses, and complete sinus opacification.
[ajnr.org]
[…] may represent fluid transudation or bleeding into the sinus 2,3.
[radiopaedia.org]