CT virtual bronchoscopy: imaging method and clinical application

To evaluate the imaging method and clinical application of CT virtual bronchoscopy (CTVB).

Fifty-two patients with bronchial and pulmonary diseases were studied with CTVB. All patients underwent fiberoptic bronchoscopy and patients with lung cancers were confirmed pathologically. Lung cancer of center type was found in 46 patients, postoperative lung cancer in 4, tracheal adenoidcystic carcinoma in 1, and bronchial diverticulum in 1. CTVB was performed using Navigator Smooth software on the workstation (Advantage Windows 3.1, GE Medical Systems). Source images included slice thickness of 3 mm or 5 mm, pitch of 1.0 or 1.5, 1.0 mm or 2.0 mm interval (overlap more than 60%) reconstruction.

CTVB could reveal vividly the tracheobronchial lumens, the cartilage rings, the carina and the left and right main bronchi, down to the fourth order of bronchial orifices, mimicing fiberoptic bronchoscopy. Among 46 patients with lung cancers of center type, fiberoptic bronchoscopy showed the masses in 45 patients and CTVB displayed the masses in 42. The sensitivity of CTVB was 93.3% and its accuracy was 93.5% (chi 2 = 1.33, 0.10 < P < 0.25). The tumors appeared as masses or nodules, causing bronchial stenosis (n = 35) or occlusion (n = 7). The bronchial rings near the masses were blurred, smooth or absent in contrast to the findings of fiberoptic endoscopy. Postoperative bronchial stump (n = 4) appeared to be smooth. Bronchial diverticulum exhibited a local concavity on CTVB and local protrusion on surface shadow display (SSD). CTVB could pass through the stenotic bronchi and detect the occlusive bronchi from the distal end.

The sensitivity of CTVB in detecting bronchial masses was higher than that of fiberoptic bronchoscopy. Combined with multiplanar reconstruction (MPR) and CTVB can demonstrate the extraluminal extension of tumors. As a noninvasive examining method, however, CTVB is limited to observe mucosal abnormalities and to obtain histologic samples.