Yehonatan Nizan Turner MD, Presenter: Nothing to Disclose

Nir Hirshoren MD, Abstract Co-Author: Nothing to Disclose

Jacob Sosna MD, Abstract Co-Author: Consultant, ActiViews Ltd Research grant, Koninklijke Philips Electronics NV

Aviv Hirschenbein MD, Abstract Co-Author: Medical Director, CMT Medical Technologies Ltd, Israel

In patients with acute rhinosinusitis and associated purulent discharge, an air fluid level is often noted. Our aim was to evaluate whether air density changes above the air fluid level may serve as an adjunct sign for acute rhinosinusitis.

Our Institutional Review Board approved this study. We retrospectively analyzed 50 CT studies of the sinuses performed at our institution in 2009. Mean patient age was 43.3 years (range 18-72). 25 patients had acute rhino-sinusitis based on clinical and CT findings; 25 patients were referred to CT for neuro-ophthalmological assessment, and had normal sinuses. Air density within each maxillary sinus was measured using a square ROI of 1 cm2, drawn 0.5 cm away from the sinus wall by an experienced radiologist. The mean and SD of the sinus air density for each maxillary sinus were calculated from five sequential CT slices. The means and SDs for 29 inflamed sinuses in 25 patients, and for 50 normal sinuses in 25 patients, were compared. Air density external to the patient was also measured for control.

Average sinus air density was significantly higher in the inflamed sinuses compared to normal aerated sinuses (-832HU vs -976 HU respectively, p<0.05). The SD for sinus air density, an expression of the heterogeneity of the air cavity, was higher in inflamed versus normal sinuses (80HU vs 4.7 HU respectively, p<0.05). Air density outside the body was almost equal in all patients, and ranged from -998.8, to -1001.9 HU.  

Air density is significantly higher in inflamed versus normal aerated sinuses, with increased heterogeneity (SD), potentially representing purulent aerosol.   

CT air density may serve as an adjunct sign in the diagnosis of acute rhinosinusitis. A larger scale study is currently underway.  

Turner, Y, Hirshoren, N, Sosna, J, Hirschenbein, A, CT Air Density as an Adjunct Sign for Acute Rhinosinusitis.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9003610.html