Grading Airway Stenosis Down to the Segmental Level Using Virtual Bronchoscopy: Airway stenosis
Compared to the central airways, we found a higher rate of false-positive stenoses in the segmental bronchi. In our study, intraluminal mucus deposition caused more false-positive segmental airway readings (seven) than false-positive central airway readings (four). It has been reported that the segmental airways seem to be more susceptible to the deposition of mucus and coagulated blood, which can only be removed by irrigation and suction on flexible bronchoscopy. This may explain why we found a lower positive predictive value for segmental airway stenosis (40.9%) than for central airway stenosis (84.4%). alta white teeth whitening
Interindividual variation of the bronchial caliber, which may cause misinterpretation of the bronchial lumen, may be more frequent on the level of the segmental bronchi. This also may contribute to our finding of a better correlation between flexible and virtual bronchoscopy in the grading of stenoses within the central (r = 0.87) than in the segmental airways (r = 0.61).
Although virtual bronchoscopy with single-detector helical CT scanning is reported to have excellent sensitivity and specificity in detecting central airway stenosis, it is limited by the relatively long scanning times needed for a narrow collimation. This is more likely to cause breathing and motion artifacts, especially in patients with airway disease that may restrict their ability to hold their breath for a sufficient length of time. This may lead to the misinterpretation of the tracheobronchial lumen and false-positive findings. Scanning time can be kept short using multirow detector CT scanning despite a thin collimation, which enhances z-axis resolution of the CT data set and consequently improves the quality of virtual bronchoscopic images. This enables the expanded use of virtual bronchoscopy not only for the central airways, but also for the segmental and subsegmental airways. When a thin collimation (eg, 4 X 1 mm) is used, virtual bronchoscopy can be reconstructed from any routine chest multidetector CT scan in retrospect, and radiograph exposure does not exceed that of a normal chest CT scan.