Sonography of the Pediatric Chest

Conventional and Contrast-enhanced US of the Lung: From Performance to Diagnosis

In recent years, lung US has evolved from a marginal tool to an integral component of diagnostic chest imaging. Contrast-enhanced US (CEUS) can improve routine gray-scale imaging of the lung and chest, particularly in diagnosis of peripheral lung diseases (PLDs). Although an underused tool in many centers, and despite inherent limitations in evaluation of central lung disease caused by high acoustic impedance between air and soft tissues, lung CEUS has emerged as a valuable tool in diagnosis of PLDs. Owing to the dual arterial supply to the lungs via pulmonary and bronchial (systemic) arteries, different enhancement patterns can be observed at lung CEUS, thereby enabling accurate differential diagnoses in various PLDs. Lung CEUS also assists in identifying patients who may benefit from complementary diagnostic tests, including image-guided percutaneous biopsy. Moreover, lung CEUS-guided percutaneous biopsy has shown feasibility in accessible subpleural lesions, enabling higher histopathologic performance without significantly increasing either imaging time or expenses compared with conventional US. The authors discuss the technique of and basic normal and pathologic findings at conventional lung US, followed by a more detailed discussion of lung CEUS applications, emphasizing specific aspects of pulmonary physiology, basic concepts in lung US enhancement, and the most commonly encountered enhancement patterns of different PLDs. Finally, they discuss the benefits of lung CEUS in planning and guidance of US-guided lung biopsy. ©RSNA, 2024 Supplemental material is available for this article.

Imaging recommendations and algorithms for pediatric tuberculosis: part 1-thoracic tuberculosis

Tuberculosis (TB) remains a global health problem and is the second leading cause of death from a single infectious agent, behind the novel coronavirus disease of 2019. Children are amongst the most vulnerable groups affected by TB, and imaging manifestations are different in children when compared to adults. TB primarily involves the lungs and mediastinal lymph nodes. Clinical history, physical examination, laboratory examinations and various medical imaging tools are combined to establish the diagnosis. Even though chest radiography is the accepted initial radiological imaging modality for the evaluation of children with TB, this paper, the first of two parts, aims to discuss the advantages and limitations of the various medical imaging modalities and to provide recommendations on which is most appropriate for the initial diagnosis and assessment of possible complications of pulmonary TB in children. Practical, evidence-based imaging algorithms are also presented.

The Role of Ultrasound in the Diagnosis of Pulmonary Infection Caused by Intracellular, Fungal Pathogens and Mycobacteria: A Systematic Review

BACKGROUND

Lung ultrasound (LUS) is a widely available technique allowing rapid bedside detection of different respiratory disorders. Its reliability in the diagnosis of community-acquired lung infection has been confirmed. However, its usefulness in identifying infections caused by specific and less common pathogens (e.g., in immunocompromised patients) is still uncertain.

METHODS

This systematic review aimed to explore the most common LUS patterns in infections caused by intracellular, fungal pathogens or mycobacteria.

RESULTS

We included 17 studies, reporting a total of 274 patients with M. pneumoniae, 30 with fungal infection and 213 with pulmonary tuberculosis (TB). Most of the studies on M. pneumoniae in children found a specific LUS pattern, mainly consolidated areas associated with diffuse B lines. The typical LUS pattern in TB consisted of consolidation and small subpleural nodes. Only one study on fungal disease reported LUS specific patterns (e.g., indicating "halo sign" or "reverse halo sign").

CONCLUSIONS

Considering the preliminary data, LUS appears to be a promising point-of-care tool, showing patterns of atypical pneumonia and TB which seem different from patterns characterizing common bacterial infection. The role of LUS in the diagnosis of fungal disease is still at an early stage of exploration. Large trials to investigate sonography in these lung infections are granted.

Diagnostic accuracy of lung ultrasonography in childhood pneumonia: a meta-analysis

This meta-analysis aimed to assess the diagnostic accuracy of lung ultrasonography in pneumonia-affected pediatric patients. Literature search of published articles in Medline, Web of Science, Scopus, Embase and Journal of Web till September 2020 were reviewed for the predescribed accuracy assessors. In compliance with the inclusion and exclusion criteria, two researchers independently screened the literature, collected the results and assessed the risks of bias using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. The pooled sensitivity and specificity, pooled positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio were estimated for the meta-analysis. The overall efficiency of lung ultrasonography (LUS) was evaluated using a summary receiver operating characteristic curve. Q and I2 statistics were used to determine heterogeneity. Meta disc software was used for the analysis of the study. Out of 1182 studies, only 29 articles were chosen; 25 of them were prospective studies and 4 studies were retrospective. The overall pooled sensitivity was 0.83 [95% confidence intervals (CI), 0.81-0.84] and specificity was 0.84 (95% CI, 0.81-0.86), depicting good diagnostic performance. LUS is an efficient imaging technique for detecting childhood pneumonia with a high accuracy rate. It is an appealing alternative to chest X rays to detect and follow-up pneumonia in children because it is simple to do, widely available, comparatively cheap and free of radiation hazards.

Pediatric lung ultrasonography: current perspectives

Ultrasonography (US) is the workhorse of pediatric imaging; however, lung US is only a recently developed application. US of the lung is based predominantly on the imaging of chest wall-air-fluid interfaces. In this review, we summarize the available literature on applications of lung US in neonatal as well as pediatric care. We describe the imaging appearance of various commonly encountered pathologies including pneumonia and respiratory distress syndrome, among others, and provide illustrative images. Finally, we describe the limitations of the technique that are essential knowledge for radiologists, critical care physicians, sonographers and technologists attempting to use lung US effectively for diagnosis and management.

Pediatric Lower Respiratory Tract Infections: Imaging Guidelines and Recommendations

Lower respiratory tract infection (LRTI) remains a major cause of morbidity and mortality in children. Various organisms cause LRTI, including viruses, bacteria, fungi, and parasites, among others. Infections caused by 2 or more organisms also occur, sometimes enhancing the severity of the infection. Medical imaging helps confirm a diagnosis but also plays a role in the evaluation of acute and chronic sequelae. Medical imaging tests help evaluate underlying pathology in pediatric patients with recurrent or long-standing symptoms as well as the immunocompromised.

Contrast-enhanced ultrasound of pediatric lungs

In addition to radiography, ultrasound (US) has long proved to be a valuable imaging modality to evaluate the pediatric lung and pleural cavity. Its many inherent advantages, including real-time performance, high spatial resolution, lack of ionizing radiation and lack of need for sedation make it preferable over other imaging modalities such as CT. Since the introduction of ultrasound contrast agents (UCAs), contrast-enhanced ultrasound (CEUS) has become a valuable complementary US technique, with many well-established uses in adults and evolving uses in children. Lung CEUS applications are still not licensed and are performed off-label, although the added value of CEUS in certain clinical scenarios is increasingly reported. The limited evidence of CEUS in the evaluation of pediatric lungs focuses primarily on community-acquired pneumonia and its complications. In this clinical setting, CEUS is used to confidently and accurately diagnose necrotizing pneumonia and to delineate pleural effusions and empyema. In addition to intravenous use, UCAs can be administered directly into the pleural cavity through chest catheters to improve visualization of loculations within a complex pleural effusion, which might necessitate fibrinolytic therapy. The purpose of this paper is to present the current experience on pediatric lung CEUS and to suggest potential additional uses that can be derived from adult studies.

The use of lung ultrasound compared to chest X-ray to diagnose pneumothorax following the Nuss procedure for pectus excavatum repair in children

BACKGROUND

Pectus Excavatum is the most common deformation of the skeletal chest wall, and the Nuss procedure is used to correct this deformation. Residual pneumothorax is a frequent postoperative complication after thoracoscopy. Primary aim of this prospective observational study was to compare the level of agreement among readers using lung ultrasound and chest X-ray.

METHODS

This was an inter-reader single-center prospective observational agreement study for lung ultrasound and chest X-ray. Three lung ultrasound evaluations were performed at the end of surgery in the operating room by two Consultant Anesthesiologist (A1 and A2) and by a medical student (A3). Chest X-ray was interpreted by a consultant Radiologist (R1) and a pool of 11 radiologists (collectively named R2). Cohen's kappa was used to evaluate the level of agreement between the two imaging techniques.

RESULTS

Sixty-eight pediatric patients were included in the study. The overall agreement among (A = Anesthesiologist) A1, A2, A3, (R = Radiologist) R1, and R2 in assessing pneumothorax was fair (k = 0.32; 95% CI 0.21-0.40). The stratified analysis showed moderate inter-reader agreement among lung ultrasound readers A1, A2, and A3 (k 0.58; 95% CI 0.44-0.71), as opposed to the fair agreement found among chest X-ray readers R1 and R2 (k = 0.39; 95% CI 0.18-0.60).

CONCLUSIONS

Our results support the use of lung ultrasound to diagnose pneumothorax after Nuss procedure. We found that the inter-reader accuracy was better with ultrasound compared to X-ray at our institution.

Lung Ultrasound Findings and Bronchiolitis Ultrasound Score for Predicting Hospital Admission in Children With Acute Bronchiolitis

OBJECTIVES

The purposes of this study were to determine the benefit of the bronchiolitis ultrasound score (BUS) in predicting hospital admission in children with acute bronchiolitis and to characterize lung sonography findings.

METHODS

This prospective observational study was performed in an academic pediatric emergency department. Children younger than 24 months presenting to the emergency department, diagnosed with acute bronchiolitis by 2 independent pediatricians were included in the study. Lung ultrasound was performed by a single sonographer, who was blinded to as much clinical information as possible. In addition, the treating physicians were blinded to the lung ultrasound findings. Logistic regression analysis models were used to identify admission predictors. Receiver operating characteristic analysis was used to evaluate the predictive value for effects of the BUS and the modified Bronchiolitis Severity Score on admission.

RESULTS

The median age of the 76 patients diagnosed with acute bronchiolitis was 6 months (interquartile range, 3.6-10 months). Forty-two (55.3%) of the 76 patients enrolled were admitted. Lung ultrasound was compatible with acute bronchiolitis in 74 patients (97%). A significant correlation was determined between modified Bronchiolitis Severity Score and BUS in children with acute bronchiolitis (r = 0.698, P < 0.001). The most effective parameter in determining admission on logistic regression analysis, independently of other variables, was BUS (P = 0.044; adjusted odds ratio, 1.859; 95% confidence interval, 1.016-3.404). Bronchiolitis ultrasound score values of 3 or greater exhibited 73.81% sensitivity and 73.53% specificity, whereas BUS values of 4 or greater exhibited 50% sensitivity and 91.18% specificity.

CONCLUSIONS

Point-of-care lung ultrasound can accurately detect pulmonary anomalies in children with acute bronchiolitis, has a close correlation with clinical findings, and is a useful tool in predicting hospital admission.

Beyond Point-of-Care Ultrasound: Bedside Ultrasound in the Diagnosis of Soft Tissue Mass

Cancer is diagnosed in 1 in 7000 children annually. Here, we report 6 cases of a mass identified by the author, a novice sonographer in a pediatric emergency medicine fellowship, using point-of-care ultrasound, from January of 2017 to May of 2018. Identification of these cases early in presentation allowed for earlier involvement of the relevant specialist and shorter time to diagnosis and treatment, and might be expected to increase parent satisfaction as well.

Diagnostic Value of Ultrasound in Detecting Causes of Pediatric Chest X-Ray Opacity

OBJECTIVES

Computed tomography is considered as the diagnostic gold standard for following up the majority of pediatric chest X-ray (CXR) opacities. However, radiation, cost, and waiting times have led to search for diagnostic alternatives. This study was conducted to determine the diagnostic accuracy of the ultrasound (US) in detecting the causes of pediatric CXR opacities.

MATERIALS AND METHODS

This study was conducted on the pediatric patients with CXR opacity referring to Dr. Sheikh Hospital in Mashhad, Iran during 2016-2017. After undergoing the US exam, the patients were followed to obtain the final diagnosis based on reference standard (RF). The accuracy of the US was calculated in detection of thoracic lesions. P value <0.05 was considered to be significant.

RESULTS

The most common diagnostic cause of CXR opacity based on RF was pneumonia (n=46, 35-38%), thymus (n=37, 28-46%), bone and soft tissue mass (n=12, 9.23%), cystic lesions (n=11, 8.46%), and diaphragmatic lesions (n=10, 7.69%), as well as intrathoracic masses and empyema (n=7, 5.38%). In only four patients (3.07%), the final diagnosis based on RF was inconsistent with the US diagnosis. The diagnostic accuracy of the US was 100% in the diagnosis of bone and soft tissue masses, diaphragmatic lesions, empyema, and normal thymus, and the accuracy was 96.92% for pneumonia, and 99.23% for cystic lesions and intrathoracic masses.

CONCLUSION

Regarding the assessed diagnostic accuracy, the US can be a reliable diagnostic tool to differentiate the main cause of pediatric CXR opacity.

Point-of-care lung ultrasound in children with non-cardiac respiratory distress or tachypnea

OBJECTIVE

The purpose of this study was to evaluate the feasibility and diagnostic benefit of point-of-care ultrasound (PoCLUS) in children with non-cardiac respiratory distress or tachypnea.

METHODS

In this prospective observational study, children aged between 1 month and 18 years with respiratory distress, tachypnea, or both, at triage were included. Concordance and accuracy of the emergency department (ED) and ultrasound diagnoses, length of stay, and time elapsing until ED and ultrasound diagnoses were calculated.

RESULTS

One hundred forty-five patients were evaluated. The mean age of the children in the study was 67 ± 58 months. Seventy-nine patients (56%) were boys. Mean length of stay in the ED was 124.6 ± 76.5 min. Mean time to ultrasound diagnosis was 29.32 ± 15.71 min, compared to 46.75 ± 32.65 min for ED diagnosis, which was significantly longer (p < 0.001). Concordance between ultrasound and ED diagnoses was almost perfect for pneumonia, acute bronchiolitis, asthma and croup (0.8 < Ƙ < 1), and good for other non-pulmonary causes (0.6 < Ƙ < 0.8). Overall concordance for all diagnoses was also good (Ƙ = 0.76). Ultrasound diagnosis was more sensitive than ED diagnosis for pneumonia, acute bronchiolitis, and other non-pulmonary causes (81.4%-74.42%; 97.3%-86.49%; and 100%-95.83%, respectively). In addition, ultrasound diagnosis was more specific than ED diagnosis for pneumonia, acute bronchiolitis and other non-pulmonary causes (100%-97.35%; 99.07%-98.15%; and 93.39%-88.43%, respectively). However, ultrasound and ED diagnoses exhibited similar sensitivity and specificity values for asthma (97.22%-97.22%; and 99.08%-100%).

CONCLUSION

PoCLUS may constitute a beneficial and rational approach in the evaluation of children with increased work of breathing in the ED, and can also expedite the diagnostic process.

Ultrasound of the pediatric chest

Cross-sectional imaging modalities like MRI and CT provide images of the chest which are easily understood by clinicians. However, these modalities may not always be available and are expensive. Lung ultrasonography (US) has therefore become an important tool in the hands of clinicians as an extension of the clinical exam, which has been underutilized by the radiologists. Reinforcement of the ALARA principle along with the dictum of "Image gently" have resulted in increased use of modalities which do not require radiation. Hence, ultrasound, which was earlier being used mainly to confirm the presence of pleural effusion as well as evaluate it and differentiate solid from cystic masses, is now being used to evaluate the lung as well. This review highlights the utility of ultrasound of the paediatric chest. It also describes the normal and abnormal appearances of the paediatric lung on ultrasound as well as the advantages and limitations of this modality.

Neonatal and pediatric thoracic ultrasonography

Ultrasound examination of the thorax (TUS) can be quite suitable for children because their unique thoracic anatomy provides many acoustic windows into the chest. This review article covers techniques, indications, and applications of TUS in neonates, infants, and children, including common aspects and applications, like pulmonary consolidation and atelectasis, pleural effusion and pneumothorax and main neonatal pathologies such as respiratory distress syndrome (RDS) and transitory tachypnea of the newborn (TTN).

Point-of-Care Ultrasound Differentiation of Lung Consolidation and Normal Thymus in Pediatric Patients: An Educational Case Series

BACKGROUND

There is a growing body of evidence to support the utility of lung point-of-care ultrasound (POCUS) in pediatric patients with multiple pulmonary pathologies, particularly pneumonia. As we increase our use of lung POCUS for pediatric patients with respiratory complaints, we must be mindful of the normal anatomy and sonographic findings within the pediatric chest and aware of how to distinguish normal findings (e.g., thymus) from pathologic findings (e.g., consolidation).

CASE REPORTS

We report four cases of pediatric patients who presented to the Emergency Department with respiratory complaints for which POCUS was able to distinguish lung consolidation and normal thymus in the anterior chest. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The use of lung ultrasound to detect pneumonia is extensively documented in the pediatric literature. Emergency physicians may not be aware of how to discriminate the normal sonographic appearance of the thymus from lung consolidation on POCUS. The ability to identify normal and pathologic findings within the pediatric chest by POCUS will be increasingly important to appropriately reduce the use of plain radiography for pediatric patients with respiratory complaints.

[Specific characteristics of chest X‑ray in childhood : Basics for radiologists]

The radiographic technique of pediatric chest X‑rays is substantially different from that in adults. In nearly all cases ap/pa X‑rays are sufficient and lateral radiographs are rarely needed. In the first years of life the thymus may overshadow the heart, the great vessels and the lung hila. The most important anatomical structures essential for diagnosing pathological findings of the lungs and mediastinum are the trachea with the bifurcation and the main bronchi with the adjacent great vessels. For the assessment of distended lungs and intrathoracic consolidations, fundamental knowledge of the anatomy in childhood and malformations which can involve the airways, the lungs, the heart, as well as systemic and pulmonary vessels are indispensable. Diseases of the pleura and the chest wall should always be investigated by ultrasound. Malignant disorders are rare in children, except for lymphomas. Optimized computed tomography (CT) and/or magnetic resonance imaging (MRI) are crucial in the diagnostic workflow of complex congenital heart diseases, complex lung and airway malformations, pulmonary complications in cystic fibrosis and the diagnostics of all tumors in order to make the right treatment decisions.