Objective: To determine the sensitivity and specificity of sinus x-rays of patients clinically diagnosed as having acute sinusitis.
Methods: Thirty consecutive adult, nonpregnant emergency department (ED) patients clinically diagnosed as having acute sinusitis and meeting study criteria were entered into the study. Sinus x-rays were obtained immediately after study entry and sinus computed tomography (CT) scans were done within 72 hours. Radiologic criteria for sinusitis were defined as more than 3 mm of mucoperiosteal thickening (MPT), an air/fluid (A/F) level, or opacification. All films were read in a blinded fashion [CT scans by two radiologists and plain film by two emergency medicine (EM) staff members and the same radiologists]. A third radiologist 'interpreted Ct scans when the initial radiologists disagreed.
Results: Sinus CT scans were obtained for 29 of 30 patients. Radiologists interpreted 28 of 29 CT scans identically, with 21 being positive for sinusitis. Sensitivity and specificity of x-rays were 57% and 88%, 62% and 88%, 67% and 75%, and 48% and 100% for the two radiologists and the two EM physicians, respectively. Four ethmoid, five frontal, and five sphenoid sinuses were opacified or had A/F levels on CT scan. No ethmoid, frontal, or sphenoid sinus was interpreted as being opacified or having an A/F level on plain film. Sensitivity and specificity of maxillary sinus opacification or A/F level on x-ray were 70% and 100%, and 70% and 100%, and 70% and 96%, and 70% and 96% for the two radiologists and the two EM physicians, respectively. Mean concordances (kappa) of x-ray and CT scan interpretations for the four reviewers were 0.34 (range, 0.30-0.39) for the diagnosis of sinusitis and 0.77 (range, 0.74-0.79) for maxillary sinus opacification or A/F level.
Conclusions: Sinus x-rays are less sensitive than sinus CT scans for demonstration of radiographic changes consistent with acute sinusitis. Sinus plain films may not be reliable enough to assist with clinical decision making. If severity of patient illness requires diagnostic certainty, more sensitive imaging studies, such as CT scans of the sinuses, should be considered.