title: Maxillary air density measurements for differentiating between acute and chronic rhinosinusitis.
abstract: OBJECTIVE
  Maxillary sinus air-fluid levels and sinus opacification may appear similar in cases of acute and chronic rhinosinusitis. Our aim was to evaluate whether air density analysis in addition to air-fluid level can be used as a metric to differentiate between cases of acute and chronic rhinosinusitis.
  
  
  METHODS
  A prospective study of three patient groups (n = 73) who underwent sinus CT was performed. A study group composed of 23 patients with clinical acute rhinosinusitis was compared with two different control groups (one with chronic rhinosinusitis and the other with healthy sinuses) with 25 patients in each. In each case air density within the maxillary sinus was measured using a region of interest of 1 cm(2), 0.5 cm away from the sinus wall. The mean and SD of air density of each maxillary sinus were calculated from five sequential CT slices. We compared the results of each group using a paired Student t test and analysis of variance.
  
  
  RESULTS
  Mean air density was significantly higher in the acutely inflamed sinuses compared with chronic sinusitis and healthy aerated sinuses (-846.6 vs -980 and -975.8 HU, respectively; p < 0.05). Sinus air density SD was greater in the acutely inflamed sinus than in chronic sinusitis and healthy sinuses (78.3 vs 17.9 and 6.8 HU, respectively; p < 0.05).
  
  
  CONCLUSIONS
  Increased sinus air density and heterogeneity may help differentiate acute from chronic rhinosinusitis.
authors.affiliation: 1 Department of Otolaryngology/Head and Neck Surgery, The Hebrew University School of Medicine, Hadassah Medical Center, Hadassah Ein-Kerem, Jerusalem, 91120, Israel.
authors.forename: Nir
authors.initials: N
authors.lastname: Hirshoren
authors.forename: Yehonatan N
authors.initials: YN
authors.lastname: Turner
authors.forename: Jacob
authors.initials: J
authors.lastname: Sosna
authors.forename: Aviv
authors.initials: A
authors.lastname: Hirschenbein
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000388:Air; D016022:Case-Control Studies; D002908:Chronic Disease; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012220:Rhinitis / Q000473:pathology*; D012852:Sinusitis / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*