Grading Airway Stenosis Down to the Segmental Level Using Virtual Bronchoscopy: Central Airways

Grading Airway Stenosis Down to the Segmental Level Using Virtual Bronchoscopy: Central AirwaysFlexible bronchoscopy revealed a total of 30 central airway stenoses. Thirteen stenoses were judged to be grade 1, and 17 were judged to be grade 2. Virtual bronchoscopy detected a total of 32 stenoses. Fourteen stenoses were judged to be grade 1, and 18 were judged to be grade 2. Figure 1 shows a grade 2 stenosis of the right main bronchus. Twenty-seven findings were true-positive, five were false-positive (ie, trachea, right upper lobe bronchus, intermediate bronchus, middle lobe bronchus, and left main bronchus), and three were false-negative (ie, right main bronchus, intermediate bronchus, and right lower lobe bronchus) [ Table 2]. In four of the five false-positive stenoses, mucus was noted on flexible bronchoscopy, which was removed through irrigation and suction. Virtual bronchoscopy had 95.5% accuracy, 90.0% sensitivity, and 96.6% specificity for the detection of central airway stenosis. The positive predictive value was 84.4%, and the negative predictive value 97.9%.
As shown in Table 3, 168 of 176 central airway regions were correctly graded with virtual bronchoscopy (Fig 2). Virtual bronchoscopy correctly graded 25 of 27 verified stenoses. Two stenoses in the intermediate bronchus were graded too high. The correlation between virtual bronchoscopic and flexible bronchoscopic grading of central airway stenosis was good (r = 0.87; p < 0.0001).
Segmental Airways
Flexible bronchoscopy revealed a total of 10 segmental airway stenoses. Three stenoses were judged to be grade 1 and seven were judged to be grade 2.
Virtual bronchoscopy found a total of 22 peripheral airway stenoses. Fourteen stenoses were judged to be grade 1 and 8 were judged to be grade 2. Figure 3 demonstrates a grade 2 stenosis of the left upper lobar posterior segmental bronchus (B II).
Fig1
Figure 1. A 52-year-old man with bronchial carcinoma of the right upper lobe bronchus and tumor infiltration of the right main bronchus. The tumor causes occlusion of the right superior lobar orifice, with additional narrowing of the right main bronchus caused by exophytic tumor growth. Top: virtual bronchoscopic CT scan view down the right main bronchus shows the tumor occluding the right upper lobe bronchus with exophytic growth (arrow) into the right main bronchus, causing a grade 2 (> 50%) stenosis. Middle: flexible bronchoscopic image from a similar point of view also reveals a grade 2 stenosis of the right main bronchus caused by exophytic tumor growth (arrow). Bottom: coronal reformatted CT scan image provides a good overview as it demonstrates the tracheal bifurcation, the occluded right upper lobe bronchus, and the tumor in the right main bronchus (arrow).
Fig2
Figure 2. A 73-year-old woman with non-small cell lung cancer of the left upper lobe causing a grade 2 (> 50%) stenosis accompanied by atelectasis of the left upper lobe including the lingula. CT virtual bronchoscopy (top) and flexible bronchoscopy (middle) both reveal an obstruction of the left upper lobe bronchus (arrows), which was correctly classified as a grade 2 stenosis with virtual bronchoscopy. Bottom: coronal reformatted CT scan image demonstrates left upper lobe atelectasis (arrow).
Fig3
Figure 3. A 56-year-old man with advanced bronchial carcinoma of the left upper lobe after radiation therapy, accompanied by atelectasis of the left upper lobe and left pleural carcinomatosis. Top: CT virtual bronchoscopy reveals an obstruction of the left upper lobar posterior segmental bronchus (B II) [arrow] and patency of the apical segmental bronchus (B I) orifice (open arrow). Middle: flexible bronchoscopic image from a similar point of view also reveals obstruction of the posterior segmental bronchus (arrow) and patency of the apical segmental bronchus orifice (open arrow). Bottom: coronal CT scan image demonstrates atelectasis of the left upper lobar posterior segmental bronchus (arrow).

Table 2—Success of Virtual Bronchoscopy at Revealing Central and Segmental Airways Stenosis in 478 Airway Regions Using Flexible Bronchoscopy as the Reference Standard

Variable Central Airways t Segmental Airways{
IFlexible

Bronchoscopy

IVirtual

Bronchoscopy

IFlexible

Bronchoscopy

IVirtual

Bronchoscopy

True-positive results 30 27 10 9
True-negative results 146 141 292 279
False-positive results 5 13
False-negative results 3 1
Evaluated regions,§ No. 176 176 302 302
Sensitivity, % 90.0 90.0
95% CI, % 73.5-97.9 55.5-99.8
Specificity, % 96.6 95.6
95% CI, % 92.2-98.9 92.5-97.6
Positive predictive value, % 84.4 40.9
95% CI, % 67.3-94.7 20.7-63.7
Negative predictive value, % 97.9 99.6
95% CI, % 94.0-99.6 98-100
Accuracy, % 95.5 95.5
95% CI, % 90.5-98.2 92.2-97.5

Table 3——Virtual Bronchoscopic Grading of Airway Stenosis Compared to That of Flexible Bronchoscopy in 478 Airway Regions

Variables CentralAirways SegmentalAirways
Total graded airway regions, No. 176 302
Correctly graded airway regions, No. 167 286
Airway regions graded too low, No. 3 1
Airway regions graded too high, No. 6 15
Correlation (r) between virtual bronchoscopy and flexible bronchoscopy when grading airway stenosis 0.87 0.61
95% CI 0.83-0.91 0.53-0.68
p value < 0.0001 < 0.0001
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