Low-dose virtual tracheobronchial endoscopy quite accurate in children
NEW YORK (Reuters Health) - Virtual tracheobronchoscopy accomplished by multidetector computed tomography (CT) at a low radiation dose is a noninvasive method for depicting tracheobronchial anomalies and stenoses in children, physicians in Germany report.
Virtual tracheobronchoscopy using CT is commonly used in adults, yielding "a three-dimensional, realistic, and detailed overview of the tracheobronchial system," lead author Dr. Christoph M. Heyer and his associates explain. However, this less invasive modality is usually avoided in children because of the radiation exposure.
The researchers' prospective study, conducted at the Ruhr-University of Bochum and published in the February issue of Radiology, compared virtual and fiberoptic tracheobronchoscopy in 45 children, mean age 4.4 years. Indications included abnormalities on chest x-rays, persistent airway obstruction, or abnormal results of pulmonary function tests or physical examination.
Flexible tracheobronchoscopy was performed with patients sedated. Approximately 2 days later, the patients underwent CT unsedated, with iopamidol as an IV contrast agent.
The radiologists reduced radiation doses to a mean of 1.1 millisieverts (mSv); for patients less than 1 year old, the mean dose was 0.8 mSv. In contrast, they note, guidelines specify doses of 11.6 mSv in men and 15.4 mSv in women for thoracic multidetector CT.
CT indicated narrowing and/or abnormality in 34 patients, while findings appeared normal in the remaining 11 patients. Compared with fiberoptic endoscopy, the virtual results represented 33 true positives, 6 true negatives, 5 false negatives and 1 false positive.
Heyer's team reports that CT with virtual tracheobronchoscopy identified all abnormal mediastinal vessels, as well as "all congenital airway abnormalities, including accessory bronchi, abnormal bronchial branching, and tracheoesophageal fistulas."
However, CT missed several cases of tracheobronchomalacia and functional airway narrowing. The authors explain, "Tracheomalacia and bronchomalacia do not account for fixed narrowing and therefore can be reliably diagnosed only at functional studies."
Overall, sensitivity was 86.8%, specificity was 85.7%, and accuracy was 86.7%.
Heyer and his colleagues suggest that virtual tracheobronchoscopy can be complementary to flexible tracheobronchoscopy during many interventions, "including stent implantation, tracheotomy, or partial lung resection."
Radiology 2007;242:542-549.