Multidetector computed tomography and virtual bronchoscopy: Role in bronchial obstruction in children.

Sir,

We read with interest manuscript titled “Subcutaneous emphysema due to bronchial foreign body demonstrated by multidetector-row computed tomography (MDCT)”, by Wani et al, published in Lung India. 2011:Oct;28(4):291-3.[1]

We wish to point out that MDCT virtual bronchoscopy (VB) is useful in evaluating bronchial stenosis and obstruction caused not only by endoluminal pathology but also by external compression and in addition it has the advantage of looking beyond stenosis. We agree with the authors that its main application lies in providing the exact location of suspected foreign body, prior to bronchoscopy. However, we would like to add that it still fails to disclose exact nature of obstructing pathology which is finally detected by rigid/ flexible bronchoscopy.[23]

It is pertinent to add here that Sodhi et al,[2] in their study of 43 children evaluated the potential use of MDCT and VB) in the evaluation of tracheobronchial patency in children with suspected bronchial obstruction and compared its findings with fibreoptic / rigid bronchoscopy or surgery. They found obstructive pathology in 26 children, which included endoluminal foreign body, mucus plugs in 13 children, endobronchial tumor in three children and extrinsic compression (lymph node, aberrant Vessels, mediastinal cysts / tumors) of the tracheobronchial tree in 10 children. In 17 children, no obstructive lesion was identified. Excellent positive correlation was obtained, between MDCT-VB and bronchoscopy/surgery. They concluded that MDCT-VB is useful in evaluating bronchial stenosis and obstruction caused by both endoluminal pathology and extrinsic causes.

VB is a non-invasive technique that provides a 3D view of internal surface of the trachea and major bronchi by using MDCT images.[4] VB enables simultaneous visualization of inner and outer structures of the tracheo bronchial tree thus clearly depicting the cause of obstruction.[45] In another study by Adaletli, et al,[5] there were 82% true positives in VB when compared with bronchoscopy.

Another aspect which we wish to emphasize is that this virtual technique does not require any additional radiation exposure in children, but provides additional information to the MDCT images, that is indicated anyway for suspected narrowing or compression of the tracheo bronchial tree. As opposed to fibreoptic bronchoscopy, the virtual technique is noninvasive and does not require general anaesthesia and can be performed with simple sedation. The other advantages of VB include visualization of airway distal to obstruction,[25] segmental and sub segmental bronchi can be evaluated easily with thin section MDCT images,[5] simultaneous evaluation of mediastinal and lung pathologies responsible for symptoms of the child, and evaluation of vascular anomalies in children.