Performance of chest ultrasound in pediatric pneumonia

doi:10.1016/j.ejrad.2016.12.032

European Journal of Radiology

Volume 88, March 2017, Pages 82-87

https://doi.org/10.1016/j.ejrad.2016.12.032 Get rights and content

Highlights

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Prospective comparison between chest X-ray and thoracic ultrasound for the detection of pneumonia in children.
•
Good correlation between X-ray and ultrasound for the detection and localization of pneumonia.
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Thoracic ultrasound has an excellent negative predictive value (99%) for pediatric pneumonia.
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Ultrasound may be used as a non-ionizing alternative to X-ray to exclude pneumonia in children.

Abstract

Objective

The objective of this study was to evaluate the performance of ultrasound in detecting lung consolidation in children suspected of pneumonia, in comparison to the current gold standard, chest X-rays.

Materials and methods

From September 2013 to June 2014, a monocentric prospective study was performed on all children between 0 and 16 years-old, referred for chest X-ray for suspected pneumonia. Each child was examined by chest ultrasound by an examiner blinded to the chest X-ray. The presence or absence of areas of consolidation, their number and location were noted for each technique. The size of the consolidations identified only on ultrasound was compared with that of consolidations visible on both techniques.

Results

143 children (mean age 3 years; limits between 8 days and 14 years) were included. Ultrasound detected at least one area of consolidation in 44 out of 45 patients with positive X-rays. Of the 59 areas of consolidation on X-ray, ultrasound identified 54. In the 8 patients with negative X-ray, ultrasound revealed 17 areas of consolidation. The mean size of consolidations visible only on ultrasound was 9.4 mm; for consolidations visible on both techniques the mean size was 26 mm (p < 0.0001).

The sensitivity and specificity of ultrasound were calculated at 98% and 92%. PPV and NPV were 85% and 99%, respectively.

Conclusion

Chest ultrasound is a fast, non-ionizing and feasible technique. With its high negative predictive value, it can replace X-rays in order to exclude lung consolidation in children, thus reducing radiation exposure in this population.

Introduction

Lower respiratory tract infections (bronchitis, bronchiolitis and pneumonia) are responsible for a large number of emergency room (ER) consultations in the pediatric population. Furthermore, according to the World Health Organization (WHO), pneumonia is the most common cause of infant mortality globally [1], which renders the importance of an adequate treatment even greater.

Pneumonia may be either viral and treated symptomatically, or bacterial and requiring antibiotic treatment. The differential diagnosis between the two types of causal agent is difficult and must take into consideration the age of the patient, the clinical presentation, lab work and imaging. Typically, bacterial pneumonia causes lung consolidation, which is an added argument for antibiotic treatment.

In everyday pediatric radiology practice, a large number of acute respiratory infections are viral infections, requiring no antibiotic treatment. However, chest X-ray is routinely performed to exclude bacterial pneumonia. In order to prevent unnecessary radiation exposure for the child, the diagnostic and performance of alternative (non-ionizing) imaging techniques should be investigated. Ultrasound is widely available in the emergency room, which recommends it as a possible alternative to X-ray.

Pulmonary consolidation is caused by replacing the normal alveolar air content with a higher density material (fluid, pus, secretions). On chest X-rays areas of consolidation appear as fluid-density opacities, ill-defined or well-defined and containing air bronchograms [2]. On ultrasound, areas of consolidation are visible if they are in contact with the pleural surface; they appear as hypoechoic, ill-defined areas with an air bronchogram and are vascularized on Doppler US [3], [4], [5] (Fig. 1).

The aims of this study were (i) to evaluate the performance of ultrasound (US) in detecting lung consolidation in comparison to the current gold standard (chest X-rays), (ii) to explore the possibility of limiting the number of chest X-rays performed for pediatric respiratory infections, by replacing them with US, and thus reducing radiation exposure.

Section snippets

Patients and methods

A monocentric prospective study was performed over a period of ten months, from September 2013 to June 2014. The investigation was approved by the ethical committee of our institution.

Patient population

This study included 143 children, aged between 8 days and 14 years (mean age 3 years 5 months, median age 2 years 7 months), of which 77 boys (53.8%) and 66 girls (46.2%). The most common symptoms were cough and fever. Lung consolidation was present in 31.7% (45/143) of cases, estimated by the percentage of positive X-rays. The mean duration of the US examination was 6.42 min (range = [2 min; 14 min], median duration = 6 min). In 7 of 136 cases a convex US probe was used, in addition to the standard

Confrontation US – chest X-ray (positive-negative)

The number of patients identified as positives or negatives for each technique is given in Fig. 3. The performance of US as a diagnostic test was found to be excellent: AUC = 0.95 (95%CI = [0.90; 0.98]), sensitivity = 98% (95%CI = [88%; 100%]), specificity = 92% (95%CI = [84%; 96%]), positive predictive value = 85% (95%CI = [72%; 93%]), negative predictive value = 99% (95%CI = [94%; 100%]).

Discussion

Chest X-ray is currently the standard imaging investigation for suspected pneumonia in children. Nevertheless, the X-ray is often normal or consistent with bronchitis, which does not require antibiotic treatment.

In our population, the percentage of positive X-rays for consolidation was 31,7%. Therefore, almost 70% of the patients referred for suspected pneumonia had negative chest X-rays for consolidation. In comparison to adults, children have a higher sensitivity to ionizing radiation

Conclusion

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¹: The authors have nothing to disclose.

View full text

Performance of chest ultrasound in pediatric pneumonia

Highlights

Abstract

Objective

Materials and methods

Results

Conclusion

Introduction

Section snippets

Patients and methods

Patient population

Confrontation US – chest X-ray (positive-negative)

Discussion

Conclusion

Media Centre, “Pneumonia”

Localization of intrathoracic lesion

Chest Roentgenology

L’échographie dans la pathologie thoracique de l’enfant

J. Radiol.

Ultrasound of the pediatric chest

Pediatr. Radiol.

Ultrasound of the chest in children (mediastinum excluded)

Eur. Radiol.

Receiver-operating characteristic (ROC) plots: a fundamental evaluation tool in clinical medicine

Clin. Chem.

The one-sample location problem

Nonparametric Statistical Methods

Statistical Methods in Medical Research

Computed tomography −An increasing source of radiation exposure

N. Engl. J. Med.

Caffey’s Pediatric Diagnostic Imaging

Elsevier Saunders, Radiation Bioeffects, Risks, and Radiation Protection in Medical Imaging in Children

The ALARA (as low as reasonably achievable) concept in pediatric interventional and fluoroscopic Imaging: striving to keep radiation doses as low as possible during fluoroscopy of pediatric patients − a white paper executive summary

Pediatr. Radiol.