Volumetric computed tomography analysis of the olfactory cleft in patients with chronic rhinosinusitis

Abstract

Background: Commonly used computed tomography (CT) staging systems for chronic rhinosinusitis (CRS) focus on the sinuses and do not quantify disease in the olfactory cleft. The goal of the current study was to determine whether precise measurements of olfactory cleft opacification better correlate with olfaction in patients with CRS.

Methods: Olfaction was assessed using the 40-item Smell Identification Test (SIT-40) before and after sinus surgery in adult patients. Olfactory cleft opacification was quantified precisely using three-dimensional (3D), computerized volumetric analysis, as well as via semiquantitative Likert scale estimations at predetermined anatomic sites. Sinus opacification was also quantified using the Lund-Mackay staging system.

Results: The overall cohort (n = 199) included 89 (44.7%) patients with CRS with nasal polyposis (CRSwNP) and 110 (55.3%) with CRS without nasal polyposis (CRSsNP). The olfactory cleft opacified volume correlated with objective olfaction as determined by the SIT-40 (Spearman's rank correlation coefficient [Rs ] = -0.461; p < 0.001). The correlation was significantly stronger in the CRSwNP subgroup (Rs = -0.573; p < 0.001), whereas no appreciable correlation was found in the CRSsNP group (Rs = -0.141; p = 0.141). Correlations between sinus-specific Lund-Mackay CT scoring and SIT-40 scores were weaker in the CRSwNP (Rs = -0.377; p < 0.001) subgroup but stronger in the CRSsNP (Rs = -0.225; p = 0.018) group when compared to olfactory cleft correlations. Greater intraclass correlations (ICCs) were found between quantitative volumetric measures of olfactory cleft opacification (ICC = 0.844; p < 0.001) as compared with semiquantitative Likert grading (ICC = 0.627; p < 0.001).

Conclusion: Quantitative measures of olfactory cleft opacification correlate with objective olfaction, with the strongest correlations seen in patients with nasal polyps.

Trial registration: ClinicalTrials.gov NCT01332136.

Keywords: X-ray computed; cone-beam computed tomography; sinusitis; smell; tomography scanners.

© 2015 ARS-AAOA, LLC.

Figures

Figure 1

3-dimensional (3-D) volume of the olfactory cleft. Orange color shows the segmented 3-D volume of the olfactory cleft, the red shaded area represents the anterior coronal section of the segmented olfactory cleft, and the blue outline is the middle coronal section of the segmented olfactory cleft.

Figure 2

Segmentation of the olfactory cleft in a patient with chronic rhinosinusitis without nasal polyps; A=anterior (36.9%); B=middle (42.1%); C=posterior (49.5%). The total 3-D volumetric opacification=45.2%.

Figure 3

Segmentation of the olfactory cleft in a patient with chronic rhinosinusitis with nasal polyps; A=anterior (83.5%); B=middle (52.7%); C=posterior (78.2%). The total 3-D volumetric opacification is 76.3%.

Figure 4

Linear correlations between olfactory cleft opacified volume and objective SIT-40 olfaction scores in CRSsNP (n=110; Rs= −0.141; p=0.141) and CRSwNP (n=89; Rs= −0.573; p<0.001). Lines represent best linear fit. CRSsNP, chronic rhinosinusitis without nasal polyposis; CRSwNP, chronic rhinosinusitis with nasal polyposis; SIT-40, 40-item Smell Identification Test.

Figure 5

Linear correlations between SIT-40 olfaction scores and sinus-specific Lund-Mackay CT scores in CRSsNP (n=110; Rs= −0.225; p=0.018) and CRSwNP (n=89; Rs= −0.275; p=0.009). Lines represent best linear fit. Solid black line indicates correlation for entire cohort (Rs= −0.490; p<0.001). CT, computed tomography; CRSsNP, chronic rhinosinusitis without nasal polyposis; CRSwNP, chronic rhinosinusitis with nasal polyposis; SIT-40, 40-item Smell Identification Test.