Advancing CT and MR imaging of the lungs and airways in children: imaging into practice

Pediatric Lung MRI: Currently Available and Emerging Techniques

OBJECTIVE. The purpose of this article is to review currently available and emerging techniques for pediatric lung MRI for general radiologists. CONCLUSION. MRI is a radiation-free alternative to CT, and clearly understanding the strengths and limitations of established and emerging techniques of pediatric lung MRI can allow practitioners to select and combine the optimal techniques, apply them in clinical practice, and potentially improve early diagnostic accuracy and patient management.

Thoracic Magnetic Resonance Imaging Applications in Children

Lung pathologies in the pediatric population can usually be detected using chest radiography. Multidetector computed tomography (MDCT) imaging is often used as a supplementary method in the evaluation of lung diseases. Recently, magnetic resonance imaging (MRI) techniques were found to be reliable in the evaluation of pulmonary diseases in the pediatric population. This review study describes the routine application of MRI examinations and the use of thoracic MRI with a particular focus in pediatric patients.

Diagnostic Accuracy of Three-dimensional Turbo Field Echo Magnetic Resonance Imaging Sequence in Pediatric Tracheobronchial Anomalies with Congenital Heart Disease

Tracheobronchial anomalies are common in congenital heart disease (CHD), including tracheobronchial stenosis, tracheal bronchus, cardiac bronchus, and bronchial isomerism, which can cause varying degrees of respiratory illness. It is necessary to assess tracheobronchial anomalies and make a preoperative airway evaluation. Multi-slice computed tomography (MSCT) and cardiac magnetic resonance imaging (MRI) are the most effective noninvasive modalities for the diagnosis of CHD and the associated tracheobronchial anomalies. However, MSCT remains an ionizing procedure despite using low dose protocols. The aim of this study was to evaluate diagnostic accuracy of tracheobronchial anomalies in patients with CHD using three-dimensional turbo field echo(3D-TFE) magnetic resonance imaging sequence for preoperative airway evaluation. The results indicated that 3D-TFE provided better image quality as compared to that of 3D-balanced turbo field echo (3D-bTFE), and it can clearly demonstrated the tracheobronchial tree and tracheobronchial anomalies in CHD. This study confirms the clinical value of 3D-TFE in diagnosing tracheobronchial anomalies and supply helpful tracheobronchial information for preoperative strategies and postoperative follow-up.

Lung magnetic resonance imaging for pneumonia in children

Technical factors have historically limited the role of MRI in the evaluation of pneumonia in children in routine clinical practice. As imaging technology has advanced, recent studies utilizing practical MR imaging protocols have shown MRI to be an accurate potential alternative to CT for the evaluation of pneumonia and its complications. This article provides up-to-date MR imaging techniques that can be implemented in most radiology departments to evaluate pneumonia in children. Imaging findings in pneumonia on MRI are also reviewed. In addition, the current literature describing the diagnostic performance of MRI for pneumonia is discussed. Furthermore, potential risks and limitations of MRI for the evaluation of pneumonia in children are described.

The presentation and management of granulomatosis with polyangiitis (Wegener's Granulomatosis) in the pediatric airway

OBJECTIVE

Granulomatosis with polyangiitis (GPA) is a necrotizing inflammatory disease that can affect the airway. The purpose of this study was to present a case of pediatric laryngotracheal GPA and provide management recommendations based on a thorough review of the literature.

DATA SOURCES

Retrospective chart and literature review REVIEW METHODS: A pediatric patient with laryngotracheal and pulmonary manifestations of GPA who underwent chemotherapy and intralesional corticosteroid injection is described. An extensive literature review of pediatric GPA affecting the larynx/trachea was also performed.

RESULTS

A pediatric patient presented with acute respiratory distress. Flexible laryngoscopy revealed a laryngeal mass. Magnetic resonance imaging showed circumferential subglottic stenosis, and chest computed tomography demonstrated multiple pulmonary nodules. Laryngeal and tracheal biopsy revealed granulation tissue and primary vasculitis. Labs demonstrated positive cytoplasmic antineutrophil cytoplasmic antibody, consistent with GPA. Methylprednisone, rituximab, cyclophosphamide, and intralesional steroid injection resulted in remission after 12 weeks. Review of the literature revealed two pediatric cases series and 10 case reports of GPA affecting the larynx or trachea.

CONCLUSIONS

There is a higher prevalence of GPA of the airway in children when compared to adults. Biopsy of the airway lesion may not be necessary and has lower diagnostic yield compared to other GPA subsites. Medical management includes induction therapy followed by maintenance therapy once the disease is in remission. Most patients will require a surgical intervention to maintain the airway.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:233-240, 2017.

Developmental lung malformations in children: recent advances in imaging techniques, classification system, and imaging findings

Congenital lung anomalies represent a diverse group of developmental malformations of the lung parenchyma, arterial supply, and venous drainage, which may present anywhere from the prenatal period through adulthood. It is imperative for radiologists to be aware of imaging techniques and imaging appearance of these anomalies across the pediatric age range. This review presents the spectrum of these lesions that are often encountered in daily clinical practice. Each anomaly is discussed in terms of underlying etiology, clinical presentation, and imaging characterization with emphasis on the most up-to-date research and treatment. Knowledge of these areas is essential for accurate, timely diagnosis, which aids in optimizing patient outcomes.

Magnetic resonance imaging of pediatric lung parenchyma, airways, vasculature, ventilation, and perfusion: state of the art

Magnetic resonance (MR) imaging is a noninvasive imaging modality, particularly attractive for pediatric patients given its lack of ionizing radiation. Despite many advantages, the physical properties of the lung (inherent low signal-to-noise ratio, magnetic susceptibility differences at lung-air interfaces, and respiratory and cardiac motion) have posed technical challenges that have limited the use of MR imaging in the evaluation of thoracic disease in the past. However, recent advances in MR imaging techniques have overcome many of these challenges. This article discusses these advances in MR imaging techniques and their potential role in the evaluation of thoracic disorders in pediatric patients.

Evaluation of pediatric thoracic disorders: comparison of unenhanced fast-imaging-sequence 1.5-T MRI and contrast-enhanced MDCT

OBJECTIVE

The purpose of this study was to investigate the efficacy of thoracic MRI with fast imaging sequences without contrast administration at 1.5 T for evaluating thoracic abnormalities by comparing MRI findings with contrast-enhanced MDCT findings.

SUBJECTS AND METHODS

A prospective study included consecutively registered pediatric patients who from December 2009 to January 2012 underwent thoracic MDCT followed within 2 days by MRI for evaluation of thoracic abnormalities. The final study sample consisted of 71 children (36 boys, 35 girls; mean age, 8.6 ± 4.5 years; range, 2 months-16 years) and 71 paired thoracic MRI and MDCT studies. Thoracic MRI was performed in the axial and coronal planes with the following fast imaging sequences: T1-weighted fast-field echo inversion prepulse, T2-weighted balanced fast-field echo multiple 2D, T1- and T2-weighted turbo spin-echo cardiac-triggering parallel imaging technique without cardiac monitoring, and STIR. Thoracic MDCT was performed with i.v. contrast administration. Two pediatric radiologists independently reviewed each MRI and MDCT study for abnormalities in the lung, large airways, and mediastinal, pleural, and musculoskeletal structures. The sensitivity, specificity, and overall accuracy of MRI were calculated. Interobserver agreement was measured with the kappa coefficient.

RESULTS

With MDCT as the reference standard, 51 of 71 (72%) patients had abnormal findings on MDCT studies, including infections in 21 (42%) cases, neoplasms in 19 (37%) cases, interstitial lung disease in seven (14%) cases, pleural effusion in three (6%) cases, and congenital bronchogenic cyst in one (2%) case. The overall diagnostic accuracy, sensitivity, and specificity of MRI for detecting thoracic abnormalities were 69 of 71 (97%), 49 of 51 (96%), and 20 of 20 (100%). Two undiagnosed findings with MRI that were detected with MDCT were mild bronchiectasis and small pulmonary nodule (3 mm). Almost perfect interobserver agreement was found between two reviewers with 70 of 71 agreements (κ = 0.97; 95% CI, 0.92-1.00; p < 0.001). CONCLUSION; MRI with fast imaging sequences without contrast administration is comparable to contrast-enhanced MDCT for detecting thoracic abnormalities in pediatric patients. Use of MRI with fast imaging sequences without contrast administration as a first-line cross-sectional imaging study in lieu of contrast-enhanced MDCT has the potential to benefit this patient population owing to reduced radiation exposure and i.v. contrast administration.

Advanced large airway CT imaging in children: evolution from axial to 4-D assessment

Continuing advances in multidetector computed tomography (MDCT) technology are revolutionizing the non-invasive evaluation of congenital and acquired large airway disorders in children. For example, the faster scanning time and increased anatomical coverage that are afforded by MDCT are especially beneficial to children. MDCT also provides high-quality multiplanar 2-dimensional (2-D), internal and external volume-rendering 3-dimensional (3-D), and dynamic 4-dimensional (4-D) imaging. These advances have enabled CT to become the primary non-invasive imaging modality of choice for the diagnosis, treatment planning, and follow-up evaluation of various large airway disorders in infants and children. It is thus essential for radiologists to be familiar with safe and effective techniques for performing MDCT and to be able to recognize the characteristic imaging appearances of large airway disorders affecting children.

Advanced functional thoracic imaging in children: from basic concepts to clinical applications

The lungs and airways are organs involved in fairly complex body functions, including ventilation, perfusion, respiratory motion and gas exchange. Imaging evaluation of the pediatric thorax is challenging because involuntary, nonsynchronous respiratory motions and cardiac pulsations degrade image quality appreciably. The extraction of clinically useful functional information from noninvasive imaging methods has been realized even in children thanks to recent technical advancements in thoracic imaging modalities. In this article, advanced functional thoracic imaging techniques in children, focusing on CT and MRI, will be explored from basic concepts to clinical applications.

Multidetector computed tomography of pediatric large airway diseases: state-of-the-art

Advances in multidetector computed tomography (MDCT) technology have given rise to improvements in the noninvasive and comprehensive assessment of the large airways in pediatric patients. Superb two-dimensional and three-dimensional reconstruction MDCT images have revolutionized the display of large airways and enhanced the ability to diagnose large airway diseases in children. The 320-MDCT scanner, which provides combined detailed anatomic and dynamic functional information assessment of the large airways, is promising for the assessment of dynamic large airway disease such as tracheobronchomalacia. This article discusses imaging techniques and clinical applications of MDCT for assessing large airway diseases in pediatric patients.

The role of rigid and flexible bronchoscopy in children

Bronchoscopy for paediatric respiratory disease is a routine procedure in paediatric pulmonology. Rigid bronchoscopy is now much less commonly used than flexible bronchoscopy. Technological advances have brought better picture quality and easier storage of video documentation. Indications with clear clinical benefit are congenital or acquired unexplained airway obstruction. In pulmonary infections or infiltrates in immunodeficient or immunosuppressed children not responding to empirical treatment a pathogen may be identified by bronchoscopy and bronchoalveolar lavage (BAL). Bronchoscopy and BAL can be indicated in children with unusual presentations of chronic cough or wheeze, and cystic fibrosis. The use of transbronchial biopsies (TBB) is established in paediatric lung transplantation. New applications and techniques are being developed, such as endobronchial ultrasound and transbronchial needle biopsy of lymph nodes and the role of airway stent placement have become better understood.

Chronic diseases of lung parenchyma in children: the role of imaging

Chronic diseases of the lung parenchyma (CDoLP) in children encompass a vast number of distinct clinico-pathological conditions. The prevalence of CDoLP has continued to increase in the last 10-15 years and the paediatric radiologist will therefore have to become more familiar with the imaging appearances of CDoLP. This review highlights some of the key imaging appearances of CDoLP, focussing mainly on airways disease. We also explore issues around technique optimisation and dose minimisation that remain of paramount importance in children.

Primary lung tumors in children and adolescents: a 90-year experience

PURPOSE

Primary lung tumors in children are rare. A wide range of histopathologic tumor types occurs. The incidence of these lesions and their outcomes are still largely unknown. This study aims to determine the incidence of different primary lung tumors in children and to contribute data leading to the development of evidence-based treatment models.

METHODS

A single institution retrospective review was performed with institutional review board approval. Patients were included if they had primary, nonhematologic lung tumors. Simple squamous papillomas subjected to endoscopic biopsy and not resected, and vascular lesions associated with multisystem lesions, such as hereditary hemorrhagic telangiectasia, were excluded. Medical records and pathologic material for patients from 1918 to 2008 were reviewed.

RESULTS

Forty patients were identified (23 boys, 17 girls) with a mean age of 9.6 years (range, 3 months to 19 years). Fourteen distinct histopathologic tumor types were identified. The most common tumor types were carcinoid (8), inflammatory myofibroblastic tumor (7), and pleuropulmonary blastoma (6). Rare pediatric lung tumors including small cell carcinoma, adenocarcinoma, and pulmonary capillary hemangiomatosis were also seen. The mortality rate was 17.5% (7) in our series. Chemotherapy was used in 23% (9) and radiation in 20% (8) of the patients. Of the 33 survivors, 28 had follow-up with a median duration of 29.5 months (mean, 63.2 months; range, 1-471 months).

CONCLUSIONS

Primary lung tumors in children are rare and histopathologically diverse. The tumor spectrum involves many types not seen in adults, and unlike adults, patients rarely have a history of exposure to external predisposing factors. Although complete resection remains the standard for treatment of most tumors, addition of adjuvant therapy is dependent on both tumor stage and histopathologic type.

Multidetector computed tomography and 3-dimensional imaging: preoperative evaluation of thoracic vascular and tracheobronchial anomalies and abnormalities in pediatric patients

In the past decade, rapid technical developments and advancements of multidetector computed tomography (MDCT) have revolutionized the preoperative imaging evaluation of thoracic vascular and tracheobronchial anomalies and abnormalities in infants and children. Multidetector computed tomography enables noninvasive, rapid, high-resolution, and 3-dimensional (3D) imaging of the thorax in pediatric patients that provides comprehensive preoperative surgical guidance for pediatric surgeons. With the increasing availability of MDCT and 3D imaging, a practical review is needed for the pediatric surgeon of the evolving role of these techniques in the preoperative evaluation of surgical lesions in infants and children. This article focuses on the review of advantages and disadvantages of MDCT in comparison to other imaging modalities, 2D and 3D imaging postprocessing techniques, and MDCT and 3D imaging appearance of various thoracic vascular and tracheobronchial anomalies and abnormalities in pediatric patients. The primary aim of this article was to facilitate the pediatric surgeons' ability to successfully incorporate MDCT and 3D imaging as a routine preoperative imaging tool for the evaluation of thoracic surgical lesions in infants and children.

Tracheobronchomalacia in infants and children: multidetector CT evaluation

Tracheobronchomalacia (TBM) is the most common congenital central airway anomaly, but it frequently goes unrecognized or is misdiagnosed as other respiratory conditions such as asthma. Recent advances in multidetector computed tomography (CT) have enhanced the ability to noninvasively diagnose TBM with the potential to reduce the morbidity and mortality associated with this condition. Precise indications are evolving but may include symptomatic pediatric patients with known risk factors for TBM and patients with otherwise unexplained impaired exercise tolerance; recurrent lower airways infection; and therapy-resistant, irreversible, and/or atypical asthma. With multidetector CT, radiologists can now perform objective and quantitative assessment of TBM with accuracy similar to that of bronchoscopy, the reference standard for diagnosing this condition. Multidetector CT enables a comprehensive evaluation of pediatric patients suspected of having TBM by facilitating accurate diagnosis, determining the extent and degree of disease, identifying predisposing conditions, and providing objective pre- and postoperative assessments. In this article, the authors present a step-by-step primer of multidetector CT imaging for evaluating infants and children with suspected TBM, including clinical indications, patient preparation, multidetector CT techniques and protocols, two- and three-dimensional processing of multidetector CT data, and image interpretation. The major aim of this article is to facilitate the reader's ability to successfully employ multidetector CT imaging protocols for evaluation of TBM in infants and children in daily clinical practice.