Paranasal sinusitis
The MRI signals in the frontal, maxillary, and sphenoid sinuses were
classified as follows 20:
0. Absence of signal: normal
1. Visible illumination of the sinus mucosa, although <5 mm:
normal
2. Thickening of the mucosal membrane ≥5 mm, although occupying less
than 50 % of the cross-section of the sinus: pathological
3. The mucosa occupies more than 50 % of the cross-sectional area,
although the sinus still contains some air: pathological
4. Total sinus opacification or fluid level: pathological
5. Polyp or retention cyst: a lesion with rounded edges surrounded by
air: pathological
6. Other: anatomic abnormalities presumed to be attributable to previous
nasal or sinus surgery: pathological
The MRI signals in the ethmoid sinuses were classified as follows20:
0. Absence of signal: normal
1. Minimal or moderate sinus opacification: normal
4. Marked or total sinus opacification: pathological
Paranasal sinusitis was defined as the presence of abnormal findings in
at least one of the paranasal sinuses detected by head MRI.