Roger Siemund MD,PhD, Presenter: Nothing to Disclose

Åke Forssell, Abstract Co-Author: Nothing to Disclose

Gunilla Holje, Abstract Co-Author: Nothing to Disclose

Radiography commonly used in imaging of suspected sinusitis has reportedly low sensitivity and specificity. The purpose was to evaluate CT of the paranasal sinuses at lower dose levels than modern computed radiography in cases of suspected acute sinusitis.

31 consecutive patients, referred for conventional radiography of the paranasal sinuses because of clinical signs of sinusitis, were included. Instead of radiography, CT examinations with parameters optimized for lowest possible radiation dose were performed on a multislice-CT (Philips Mx8000 IDT, 16 row). Axial and coronary MPR sections (2 mm) were reconstructed and used for reading. Two experienced radiologists rated the images for visibility of mucosal thickening, fluid levels in the large sinuses and visibility of anatomical key structures (infundibulum of maxillary sinus, ethmoidal cells, frontonasal recess, medial orbit wall). A 4 grade scale (1 = excellent, 2 = good, 3 = fair (still diagnostic), 4 = not sufficient) was used.

The rating for all sinuses was excellent and good in all cases, regardless of the presence of pathological changes (mean 1.02). The mean for the infundibulum and the frontonasal recess was 1.3 (in no case worse than 3). The average for the medial orbital wall was 1.8 with normal ethmoidal cells. When there were soft tissue changes in the ethmoidal cells the mean dropped to 2.3 and 13 % of these cases were rated as not sufficient (= 4). The effective dose of computed radiography (Fuji, ST-VI) with 3 projections is 0.05 mSv in our institution. Volume CTDI of the minimal dose CT examinations was 0.7 mGy and the average effective dose 0.02 mSv. The radiation dose of the minimal dose CT examination corresponds to only 5 % of a normal dose CT of the paranasal sinuses on our scanner.

Minimal dose multislice-CT provides image quality sufficient for adequate assessment of pathological changes in the paranasal sinuses in acute sinusitis. Replacing radiography of the paranasal sinuses with minimal dose multislice-CT saves radiation dose and provides better diagnostic quality particularly regarding the frontal, ethmoidal and sphenoidal sinuses.

Siemund, R, Forssell, Å, Holje, G, Minimal Dose Multislice-CT of the Paranasal Sinuses: Higher Diagnostic Quality Than Computed Radiography with Less Dose.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4415254.html