Three-slice computerized tomography for the diagnosis and follow-up of rhinosinusitis

Abstract

Plain sinus radiography is the imaging technique most frequently used to investigate suspected rhinosinusitis, but it has low diagnostic sensitivity. Contiguous paranasal computerized tomography (CT) gives detailed information about the pathology, anatomy and anatomical variations of the paranasal sinuses, but this method also has limitations. The cost of using this technique for all cases of suspected rhinosinusitis is prohibitive, and complete CT scans involve considerable radiation exposure. The aim of this study was to devise a CT protocol for diagnosing and following rhinosinusitis that is more economical and involves much less radiation exposure than contiguous CT. In this retrospective study, three physicians independently reviewed the contiguous coronal paranasal CT studies of 136 patients. The study population comprised the adult patients who were investigated for suspected chronic rhinosinusitis. All scans had been obtained at the second visit, after the patient had completed a 3-week course of medical treatment. For each case, the same three slices were selected to form the "three-slice CT" exam, and the same physicians independently evaluated this set. Using the results from the contiguous set as the gold standard, we calculated the sensitivity and specificity of three-slice CT for identifying rhinosinusitis. The sensitivity and specificity of three-slice CT for identifying inflammatory sinus disease were 95.1 and 92.6%, respectively. Three-slice CT is a valuable method for diagnosing and following rhinosinusitis cases, and would be cheaper and involve less radiation exposure than contiguous coronal CT. However, despite the high cost and greater radiation exposure, contiguous CT remains the gold standard for evaluating detailed sinus anatomy and disease progression.

Assessment of the Diagnostic Accuracy of Limited CT Scan of Paranasal Sinuses in the Identification of Sinusitis

“…The indication and the necessity for plain X-rays in diagnosis and further management of sinusitis has declined over the last decade (4, 7). Conventional X-ray findings are correlated with operative finding only in half of the patients with sinusitis (3). The limited sensitivity of these films has led to the increased use of paranasal sinus CT that presents detailed images of the sinuses and provides the examiner a clear view of the regions which are important in the pathogenesis of sinusitis.…”

“…The limited sensitivity of these films has led to the increased use of paranasal sinus CT that presents detailed images of the sinuses and provides the examiner a clear view of the regions which are important in the pathogenesis of sinusitis. These regions, especially the anterior ethmoid cells and ostiomeatal complex, are not well delineated on conventional X- rays (3). Coronal CT with section thickness of 3 to 4 mm is the image modality of choice for sinusitis (8, 9).…”

“…Paranasal sinus CT has high sensitivity and specificity for sinusitis. However, this modality is costly and involves greater radiation exposure than plain radiographs, and these features restrict its application (3-6). These limitations lead to modification of coronal CT scan, resulting in a variety of "limited” studies.…”

“…These limitations lead to modification of coronal CT scan, resulting in a variety of "limited” studies. Minimizing the level of radiation delivered to the patient is as important as obtaining a high-quality scan (3). …”

“…In addition, reducing the number of slices in routine contiguous paranasal CT is another approach that is used to diminish expenditure and radiation exposure. Various terms have been used such protocols including limited CT, screening coronal CT and CT mini-series (3). In our study from the complete sinus CT scan, the limited series were obtained by blocking from view all the other cuts and leaving the radiologist only 10 slice to read.…”