Three-dimensional volumetric measurements and analysis of the maxillary sinus.

Background: Multiple chronic rhinosinusitis (CRS) staging systems have been developed in an attempt to correlate symptoms with radiological imaging results. Currently, no perfect system exists. We sought to analyze the maxillary sinus (MS) using three-dimensional volumetric measurements and advanced high-resolution CT imaging.

Methods: We reviewed MS CT scans from 50 control subjects and 50 subjects with documented CRS involving at least one MS. The following measurements were recorded: (1) volume of MS free air, (2) MS mucosal thickening, and (3) MS lateral wall bony thickness. Average Hounsfield unit (HU) values for mucosal thickening among CRS subjects were also recorded. Values are expressed as mean ± SD and median. Values from the CRS patients were compared with healthy controls using Student's t-tests.

Results: Among controls (n = 50), volumes (mL) of right and left MS were 24.1 ± 9.7 and 24.7 ± 9.0, respectively. Among CRS patients (n = 50), the portion of mucosal disease to total sinus volume was 51.8% (right) and 50.7% (left). Mean bony thickness (mm) in controls was 0.98 ± 0.2 (right) and 1.0 ± 0.3 (left). CRS patients had significantly greater bony thickness 1.9 ± 0.8 (right) and 2.0 ± 0.9 (left; p = 0.0001). HU for diseased MS were 30.1 ± 18.7 (right) and 35.7 ± 22.1 (left).

Conclusion: Three-dimensional volumetric analysis combined with HU calculations and bony thickness measurements represents a new and unique way to evaluate CT scans in patients with CRS. Additional studies correlating symptoms with imaging findings as well as analysis of all paranasal sinuses is the next step toward a novel staging system.