Abstract

Objective: We sought to calculate the sensitivity, specificity, negative predictive value, and positive predictive value of a limited sinus computed tomographic (CT) scan for sinus disease.

Methods: We conducted a retrospective case series. Inclusion criteria included a sinus CT scan obtained between April 1999 and November 2000. From the complete sinus CT scan, the limited series were obtained by blocking from view all the other cuts and leaving the radiologist only four slices to read (midfrontal, anterior maxillary sinuses, posterior maxillary sinuses, and midsphenoidal). The complete CT scan was the “gold standard.”

Results: Fifty-one patients were eligible. We observed 81.3% sensitivity, 89.5% specificity, a 73.9% negative predictive value, and a 92.9% positive predictive value for the limited CT scan for the detection of sinus disease. This sensitivity and specificity were higher than reported in the literature for plain films.

Conclusion: The limited sinus CT scan is superior to plain radiographs but is not as good as the full CT scan in the evaluation of sinusitis.

Sinusitis is a common disease; its prevalence is approximately 50 million in the United States. ¹ Plain radiographic films are frequently used in clinical practice for the evaluation of nasal and paranasal sinus disease even though this radiologic examination lacks accuracy. ²A sinus computed tomographic (CT) scan has been shown to be superior to radiographs in evaluating paranasal sinuses. ² McAlister et al ³ compared plain radiographs and CT scans in 70 infants and children with recurrent sinusitis. In their study, a discrepancy was seen in 74% of patients; 46% of patients with a normal radiographic result had abnormal findings on the CT scan, and 34% of patients with an abnormal radiograph had normal findings on the CT scan. Burke et al ⁴ studied 30 adult patients comparing sinus radiographs with CT scans in acute sinusitis. They found that radiographs had a sensitivity of 48 to 67% and a specificity of 75 to 100% depending on the reader.

Complete sinus CT scan is considered the “gold standard” for evaluating paranasal sinus disease. However, this modality is expensive and exposes the patient to a high dose of radiation, especially for the radiosensitive orbital lens. ⁵ A four-cut miniseries sinus CT scan could be a reasonable alternative to both plain films and a complete sinus CT scan. A four-cut CT scan uses 80% less radiation than a complete CT scan, ⁵ and it is cheaper than a CT scan. Wippold et al ⁶ studied 25 adult patients with clinical history and findings suggestive of sinusitis (200 sinus compartments total, 8 for each patient); the limited CT scan agreed with the complete CT scan in 82% of the 200 sinus compartments studied. Goodman et al ⁷studied 44 patients and found that the sensitivity and specificity of limited sinus CT scans are 93.3 and 89.3%, respectively.

The primary objective of this study was to calculate the sensitivity, specificity, negative predictive value, and positive predictive value of a four-cut sinus CT scan, with the gold standard being the complete sinus CT scan. Depending on the sensitivity and specificity of the miniseries CT scan compared with the complete CT scan and the reported values for plain radiographs, the miniseries could be the initial test of choice for workup of clinically suspected sinusitis.

Key Points

* A miniseries computed tomographic (CT) scan has a sensitivity of 81% and a specificity of 89% for detecting sinus disease compared with a complete CT scan.

* Given similar cost, the four-cut sinus CT scan is the recommended diagnostic test over plain radiographs because of its higher sensitivity and specificity.