Bronchial foreign body aspiration

Liguo Yao, MD1; Zihan Ma, MD1; Li Liang, MD1; Shengfang Xu, MD1; Pengyun Cheng, MD2; Xinglong Liu, MD2

1 Department of Radiology, Gansu Provincial Maternity and Child-care Hospital, Lanzhou, P. R. China

2 Siemens Healthineers, China

A 13-month-old girl had a choking event after accidentally swallowing a peanut and was presented to the emergency department in our hospital. Auscultation revealed suppressed respiration of the right lung. A bronchial foreign body aspiration (FBA) was suspected and a CT examination was immediately performed, using an ultra-low dose scan protocol for diagnosis.
CT images revealed a nodular isodense opacity, blocking the right main bronchus. The right lung appeared hyperlucent in comparison to the left one, suggesting hyperinflation due to the valve effect. Multiple patchy opacities were visualized in the right lower lobe, suggesting local infiltration. The mediastinum and the trachea were slightly shifted to the right. Subsequently, a bronchoscopy was performed and the peanut was successfully retrieved.
Coronal MPR, MinIP and VRT images show a nodular isodense opacity blocking the right main bronchus. The right lung appears hyperlucent in comparison to the left one, suggesting hyperinflation due to the valve effect. Multiple patchy opacities seen in the right lower lobe, suggest local infiltration.

Courtesy of Department of Radiology, Gansu Provincial Maternity and Child-care Hospital, Lanzhou, P. R. China

Fig. 1: Coronal MPR (Fig. 1a), MinIP (Fig. 1b) and VRT (Fig. 1c) images show a nodular isodense opacity (arrows) blocking the right main bronchus. The right lung appears hyperlucent in comparison to the left one, suggesting hyperinflation due to the valve effect. Multiple patchy opacities (Fig. 1a, dotted arrows) seen in the right lower lobe, suggest local infiltration.
Foreign body aspiration (FBA) is a common pediatric emergency. It can be life-threatening or cause irreversible lung/airway damage if diagnosis and treatment are not promptly carried out. Radiography, sometimes in combination with fluoroscopy, used to be the first-line imaging modality when airway FBA has been suspected. However, a recent study [1] has shown that ultralow-dose CT can be performed at an equivalent dose level, using tin filter technology, as a first and only diagnostic tool in emergency settings. The CT attains higher sensitivity, specificity, predictive positive and negative values, as well as accuracy. A tin filter optimizes the X-ray spectrum by filtering out most low-energy photons and leaves a narrow, high-energy spectrum, thus reducing the radiation dose to the patient. It also improves air/soft tissue contrast and reduces beam hardening. In this case, the same technique is applied in combination with other standard dose reduction techniques, such as CARE Dose4D (automatic controlled tube current modulation) and ADMIRE (Advanced Modeled Iterative Reconstruction), achieving optimal image quality at ultra-low dose. It is also noteworthy that an ultra-fast scan mode - “Turbo Flash mode” - is performed which enables a complete thorax scan in 0.31 s in free breathing. Three-dimensional images can be displayed using multiplanar reconstruction (MPR), minimum intensity projection (MinIP) and volume rendering technique (VRT). The optimal image quality helps the physicians in reaching a confident diagnosis, avoiding the risk of negative bronchoscopy outcomes and operative costs.

Scanner

Scan area

Thorax

Scan mode

Turbo Flash mode

Scan length

175 mm

Scan direction

Cranio-caudal

Scan time

0.31 s

Tube voltage

Sn100 kV

Effective mAs

81 mAs

Dose modulation

CARE Dose4D

CTDIvol

0.28 mGy

DLP

5.7 mGy*cm

Rotation time

0.25 s

Pitch

2.0

Slice collimation

192 x 0.6 mm

Slice width

1.0 mm

Reconstruction increment

0.7 mm

Reconstruction kernel

Br59, ADMIRE4