Purpose or Case Report: The 320-row multidetector computed tomography (MDCT) enables the scanning of a maximum length of 160 mm by volume scanning (VS). Dynamic volume scanning (DVS) with MDCT enables the development of a 4D dynamic image.
The 3D findings of tracheobronchial imaging in children who cannot control their breathing fail to reveal the phase of breathing in which the image was taken, which affects the accuracy of the diagnosis of tracheobronchial stenosis. Imaging by 4D-DVS enables the accurate observation of the tracheal dynamics in association with the respiratory kinetics, thus revealing the mechanism of the former. Furthermore, 4D-DVS would enable the imaging of the cardiac blood vessels by a contrast study simultaneously with the imaging of the stenosed area.
We assessed the efficacy of the 4D-DVS imaging technique in the diagnosis of pediatric tracheobronchial stenosis.
Methods & Materials: The study included 28 pediatric patients who underwent tracheobronchial imaging by 4D-DVS between January 1, 2013 and September 28, 2015 (age: 0¬–3 years old, median age: 1 year). All examinations were performed using a 320-row MDCT. The designated scan area was from the larynx to the bronchus or the lower end of the chest. Depending on the physique of the patient, the scanning length was set between 80 mm and 160 mm. The scanning parameters were: 80 kV tube voltage, CT-AEC tube current, 160–320 × 0.5 mm collimation, 0.35–1.0 s rotation time, and 0.5-mm reconstruction interval.
The efficacy of 4D-DVS was assessed by evaluating the findings of the tracheal dynamic imaging. The dynamic images were evaluated for the visualization of the constriction causing the tracheobronchial stenosis, and the 3D visualization of the breathing dynamics. The exposure dose of the DVS was determined from the dose length product (DLP）value of the dynamic tracheal scan.
Results: Of the 28 patients who underwent dynamic CT scanning, 19 patients were diagnosed with tracheobronchial stenosis. In 11 of the 19 patients, the stenoses were associated with respiratory kinetic images. Additionally, a ring-sling complex was identified in two of six patients who underwent contrast imaging simultaneously with DVS. The radiation dose of the DVS was higher than that of VS.
Conclusions: DVS is an effective technique for the diagnosis of tracheobronchial stenosis associated with the breathing dynamics. However, it is necessary to be cautious about the high radiation dosages in DVS.