Incidental CT Findings Influence Subjective, Objective Chronic Rhinosinusitis Scores

Axial plain / sagittal cut of CT scan showing inflammation of both sides maxillary sinuses

The 22-item Sinonasal Outcome Test (SNOT-22) is a widely used patient-reported measure of the burden of chronic rhinosinusitis. However, multiple studies have shown it doesn’t correlate well with radiologic scores. This presents a quandary because when considered individually, both subjective and objective scores are reliable for assessing chronic rhinosinusitis.

Researchers at Brigham and Women’s Hospital sought to answer whether the association between SNOT-22 and CT results could be improved by rating partial opacification more precisely. They determined that the relationship between the two assessment methods is affected by incidental causes of opacification.

Allen Zhou, MD, resident at the Harvard Combined Otolaryngology–Head and Neck Surgery Residency Program, Anthony Prince, MD, otolaryngologist in the Division of Otolaryngology–Head and Neck Surgery at Brigham and Women’s Hospital, Alice Maxfield, MD, otolaryngologist and the site program director, Carleton Eduardo Corrales, MD, a surgeon in the division, and Jennifer J. Shin, MD, an otolaryngologic surgeon and vice chair of Faculty Development in the Department of Surgery, and colleagues detail the findings in Otolaryngology—Head and Neck Surgery.


The researchers studied 233 adults (70% female; mean age 50) who had a primary complaint of rhinosinusitis or nasal drainage and underwent sinus CT within one month of completing the SNOT-22. In order to include the full range of normal and abnormal subjects, the study was not restricted to those diagnosed with chronic rhinosinusitis.

Three systems were used to score CT images:

  • The Lund–Mackay scale is widely used to score each of the paired paranasal sinuses and osteomeatal complexes as 0 (no abnormality), 1 (partial opacification) or 2 (complete opacification). Thus, for example, patients with 2% opacification of a sinus receive the same score as those with 98% opacification
  • The Zinreich scale is a modification of the Lund–Mackay scale that provides additional nuance for scoring the ”partial” state. Each of the paired paranasal sinuses and osteomeatal complexes is scored as 0 (no opacification), 1 (1–25%), 2 (26–50%), 3 (51–75%), 4 (76–99%), or 5 (100%)
  • Direct measurement of the maximum thickness of the mucosa in each of the paired sinuses and osteomeatal complexes

Overall Results

SNOT-22 nasal scores were significantly associated with CT results when excluding those with incidental findings, regardless of the radiologic scoring mechanism utilized:

  • Lund-Mackay regression coefficient 0.321, p=0.046
  • Zinreich 0.340, p=0.033
  • Maximum mucosal thickness 0.316, p=0.040

However, when incidental findings were present, this relationship subsided. They found that SNOT-22 overall scores, sleep scores, and psychological domain scores had no significant association with imaging results, regardless of the radiologic scoring system utilized.

Impact of Incidental Findings

CT results showed that 22% of patients had mucous retention cysts, and 2% had periapical dental disease.

The investigators then stratified SNOT-22 scores by the domain (nasal, ear, sleep and psychological). When incidental findings were absent, worse SNOT-22 nasal scores were associated with worse results on all CT scoring systems:

  • Lund-Mackay coefficient, 0.321 (P=0.046)
  • Zinreich, 0.340 (P=0.033)
  • Maximal mucosal thickness, 0.316 (P=0.040)

Whether or not these incidental findings were present, the lack of relationship between SNOT-22 overall scores and imaging results persisted.

Negative associations were detected between SNOT-22 ear scores and imaging results when incidental findings were present:

  • Lund-Mackay coefficient, −0.735 (P=0.011)
  • Zinreich, −0.584 (P=0.049)
  • Maximal mucosal thickness, −0.723 (P=0.015)


Clinicians reflexively distinguish between true rhinosinusitis imaging findings and comorbid nasal conditions or incidental findings. CT scoring systems, however, account only for opacification.

That distinction may become increasingly troublesome. In clinical trials, predefined criteria can exclude patients whose CT findings are not truly positive for chronic rhinosinusitis. However, a growing number of studies are based on retrospective chart reviews using national registries and other databases. For that research, current methods of CT scoring could be improved by formally accounting for incidental findings.

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