RadioGraphics
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Published online February 25, 2008, 10.1148/rg.e29
This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Right arrow CME Test (opens in a new window)
Right arrow AVI Movie
Right arrow All Versions of this Article:
e29v1
28/3/e29    most recent
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Yedururi, S.
Right arrow Articles by Krishnamurthy, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Yedururi, S.
Right arrow Articles by Krishnamurthy, R.
Related Collections
Right arrow Magnetic Resonance Imaging
Right arrow Pediatric Radiology
RadioGraphics 2008;28:e29
© RSNA, 2008

Online Only

Multimodality Imaging of Tracheobronchial Disorders in Children1

Sireesha Yedururi, MBBS, MD, R. Paul Guillerman, MD, Taylor Chung, MD, Richard M. Braverman, MD, Megan K. Dishop, MD, Carla M. Giannoni, MD, and Rajesh Krishnamurthy, MD

1 From the Edward B. Singleton Department of Diagnostic Imaging, Texas Children’s Hospital, MC 2-2521, 6621 Fannin St, Houston, TX 77030 (S.Y., R.P.G., T.C., R.M.B., R.K.), and the Departments of Radiology (S.Y., R.P.G., T.C., R.M.B., R.K.), Pathology (M.K.D.), and Otorhinolaryngology (C.M.G.), Baylor School of Medicine, Houston, Tex. Presented as an education exhibit at the 2006 RSNA Annual Meeting. Received November 21, 2007; revision requested December 14; revision received and accepted February 7, 2008. Address correspondence to the author (email: yedururi{at}yahoo.com).


   Abstract
Top
 Abstract
Learning Objectives:
 Introduction
 Clinical Manifestations
 Imaging Approach
 Classification of Disorders...
 Conclusion
 References
 
The trachea and bronchial airways in children are subject to compromise by a number of extrinsic and intrinsic conditions, including congenital, inflammatory, infectious, traumatic, and neoplastic processes. Stridor, wheezing, and respiratory distress are the most common indications for imaging of the airway in children. Frontal and lateral chest and/or neck radiography constitute the initial investigations of choice in most cases. Options for additional imaging include airway fluoroscopy, contrast esophagography, computed tomography (CT), and magnetic resonance (MR) imaging. Advanced imaging techniques such as dynamic airway CT, CT angiography, MR angiography, and cine MR imaging are valuable for providing relevant vascular and functional information in certain settings. Postprocessing techniques such as multiplanar reformatting, volume rendering, and virtual bronchoscopy assist in surgical planning by providing a better representation of three-dimensional anatomy. A systematic approach to imaging the airway based on clinical symptoms and signs is essential for the prompt, safe, and accurate diagnosis of tracheobronchial disorders in children.


   Learning Objectives:
Top
 Abstract
 Learning Objectives:
Introduction
 Clinical Manifestations
 Imaging Approach
 Classification of Disorders...
 Conclusion
 References
 
After reading this article and taking the test, the reader will be able to:

  1. Review the clinical presentation and imaging manifestations of various tracheobronchial disorders encountered in children.
  2. Discuss indications for advanced imaging and postprocessing techniques in evaluating the pediatric airway.
  3. Provide a systematic approach for classifying and imaging tracheobronchial disorders in children.


   Introduction
Top
 Abstract
 Learning Objectives:
 Introduction
Clinical Manifestations
 Imaging Approach
 Classification of Disorders...
 Conclusion
 References
 
"Always look at the airway" is an oft-repeated maxim during teaching rounds in pediatric radiology. Airway disorders are potentially acutely life-threatening, and interpretation of chest radiographs or images from any other chest imaging modality in the pediatric population is incomplete without airway evaluation. The spectrum of disorders involving the tracheobronchial tree is diverse, with some of the conditions unique to the pediatric population. The smaller airway caliber, coupled with the greater collapsibility of the airway in infants and young children, contributes to early and more symptomatic airflow disturbances, even with minor amounts of airway edema and mucus, compared with those in adults. In this article, we discuss and illustrate the clinical and imaging manifestations of some common and uncommon pediatric tracheobronchial disorders, along with a systematic imaging approach to their diagnosis. Correlation with endoscopic and pathologic findings is provided where instructive. We have included only the conditions that involve the trachea and proximal bronchi. Conditions involving the nasal cavity, pharynx, and larynx proximally and distal bronchi and lungs distally are beyond the scope of this article.


   Clinical Manifestations
Top
 Abstract
 Learning Objectives:
 Introduction
 Clinical Manifestations
Imaging Approach
 Classification of Disorders...
 Conclusion
 References
 
Clinical presentation varies from asymptomatic to acute-onset respiratory distress (Table 1). Stridor and wheezing are the two most common clinical signs attributable to airway obstruction. The obstruction may be classified as fixed versus dynamic, or intrathoracic versus extrathoracic. Inspiratory stridor and prolonged inspiration are present with extrathoracic obstruction. Prolonged expiration, wheezing, and use of accessory expiratory muscles are seen with intrathoracic obstruction. Not all that wheezes indicates asthma. It is sometimes difficult to distinguish the wheeze that is heard with asthma (responds to bronchodilator therapy) from that heard in tracheomalacia (sometimes relieved in prone position) (1). Gastroesophageal reflux and silent aspiration may also result in wheezing in children (2). Failure to thrive is present in some infants with tracheomalacia.


View this table:
[in this window]
[in a new window]

  		Table 1. Clinical Presentations
 

   Imaging Approach
Top
 Abstract
 Learning Objectives:
 Introduction
 Clinical Manifestations
 Imaging Approach
Classification of Disorders...
 Conclusion
 References
 
Table 2 summarizes the questions to be answered with imaging to arrive at a reasonable differential diagnosis.


View this table:
[in this window]
[in a new window]

  		Table 2. Questions to Be Answered at Imaging
 
Plain Radiography, Airway Fluoroscopy, and Upper Gastrointestinal Series
A systematic imaging approach beginning with anteroposterior and lateral radiography of the neck, anteroposterior and lateral radiography of the chest, and additional imaging tailored to the clinical picture is required. Airway fluoroscopy readily demonstrates dynamic airway collapse during expiration in children with suspected tracheobronchomalacia. When an endobronchial foreign body is a consideration, decubitus chest radiography may be helpful.The observation of contralateral mediastinal shift and ipsilateral paradoxical or restricted hemidiaphragm motion during breathing supports the diagnosis of ball-valve air trapping due to an endobronchial foreign body. An upper gastrointestinal series with esophagography may be useful for demonstrating gastroesophageal reflux in asthmatic patients who are silent aspirators (2). An upper gastrointestinal series is also helpful for establishing the diagnosis of vascular rings and slings, although computed tomography (CT) or magnetic resonance (MR) imaging is eventually required for better anatomic delineation and presurgical planning (discussed in one of the following sections on vascular rings and slings).

Cross-sectional Imaging (CT and MR Imaging)
Subsequent sections of this article illustrate the importance of cross-sectional imaging techniques in the diagnosis of various extrinsic and intrinsic lesions involving the trachea and bronchi. Compared with MR imaging, CT has potential risks of radiation exposure and adverse reactions to contrast media. However, CT is faster, less often requires sedation, has better spatial resolution, and is less compromised in the presence of metallic devices. Contemporary multidetector CT scanners can generate the high-quality volumetric data sets required for multiplanar and three-dimensional (3D) image reconstruction, including volume-rendered imaging and virtual bronchoscopy. One substantial advantage of CT over bronchoscopy is its ability to show synchronous lesions distal to obstructive lesions not passable by the bronchoscope. CT can also depict the effects (eg, collapse, air trapping, mucus plugging) of a proximal obstructive lesion on the distal airways and lungs.

Dynamic CT and MR imaging techniques are useful for evaluation of the airway in patients with suspected tracheobronchomalacia or dynamic airway compression. In cooperative children, CT images can be acquired during volitional breath-holding at full inspiration and end expiration to depict maximal changes in airway caliber. In uncooperative children, CT images can be acquired at desired degrees of airway distention by the controlled-ventilation technique used in sedated patients without intubation. With this technique, several sequential inspirations are augmented by face-mask ventilation to induce hypocarbia and the Hering-Breuer reflex, which results in brief apneic periods during which images can be acquired. In uncooperative children in whom the controlled-ventilation technique is not feasible or available, cine CT can be used to rapidly acquire images of the airway throughout the respiratory cycle during free breathing. After the site of suspected airway stenosis or malacia is located, CT images are rapidly and sequentially acquired at the same axial level by setting the table increment to zero. With the sub-half-second gantry rotation times and partial scan reconstruction capabilities of modern CT scanners, cine CT technique can provide multiple images of the airway during inspiration and expiration, even in tachypneic patients. Multiplanar and 3D volume-rendered image reconstructions (Fig 1) further elucidate the anatomic relationships in dynamic airway compression by structures extrinsic to the airway (3,4). The use of cine MR imaging during coughing for dynamic evaluation of tracheal collapsibility in patients with tracheomalacia has been described (5).


Figure 1A
View larger version (31K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 1a:  Images from cine CT of 1-year-old girl with complex congenital heart disease including ventricular septal defect, hypoplastic aortic arch, and midline descending thoracic aorta, who presented with recurrent respiratory distress. Coronal (a, b) and volume-rendered (c, d) CT images obtained during inspiration (a, c) and expiration (b, d) demonstrate collapse of the left mainstem bronchus (arrows) during expiration. (e) An animated GIF file shows dynamic left mainstem bronchus collapse during expiration. (f) Axial contrast-enhanced CT image depicts the left mainstem bronchus (arrow) compressed between the descending thoracic aorta and pulmonary artery.

 

Figure 1B
View larger version (84K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 1b:  Images from cine CT of 1-year-old girl with complex congenital heart disease including ventricular septal defect, hypoplastic aortic arch, and midline descending thoracic aorta, who presented with recurrent respiratory distress. Coronal (a, b) and volume-rendered (c, d) CT images obtained during inspiration (a, c) and expiration (b, d) demonstrate collapse of the left mainstem bronchus (arrows) during expiration. (e) An animated GIF file shows dynamic left mainstem bronchus collapse during expiration. (f) Axial contrast-enhanced CT image depicts the left mainstem bronchus (arrow) compressed between the descending thoracic aorta and pulmonary artery.

 

Figure 1C
View larger version (108K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 1c:  Images from cine CT of 1-year-old girl with complex congenital heart disease including ventricular septal defect, hypoplastic aortic arch, and midline descending thoracic aorta, who presented with recurrent respiratory distress. Coronal (a, b) and volume-rendered (c, d) CT images obtained during inspiration (a, c) and expiration (b, d) demonstrate collapse of the left mainstem bronchus (arrows) during expiration. (e) An animated GIF file shows dynamic left mainstem bronchus collapse during expiration. (f) Axial contrast-enhanced CT image depicts the left mainstem bronchus (arrow) compressed between the descending thoracic aorta and pulmonary artery.

 

Figure 1D
View larger version (105K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 1d:  Images from cine CT of 1-year-old girl with complex congenital heart disease including ventricular septal defect, hypoplastic aortic arch, and midline descending thoracic aorta, who presented with recurrent respiratory distress. Coronal (a, b) and volume-rendered (c, d) CT images obtained during inspiration (a, c) and expiration (b, d) demonstrate collapse of the left mainstem bronchus (arrows) during expiration. (e) An animated GIF file shows dynamic left mainstem bronchus collapse during expiration. (f) Axial contrast-enhanced CT image depicts the left mainstem bronchus (arrow) compressed between the descending thoracic aorta and pulmonary artery.

 

Figure 1E
View larger version (68K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 1e:  Images from cine CT of 1-year-old girl with complex congenital heart disease including ventricular septal defect, hypoplastic aortic arch, and midline descending thoracic aorta, who presented with recurrent respiratory distress. Coronal (a, b) and volume-rendered (c, d) CT images obtained during inspiration (a, c) and expiration (b, d) demonstrate collapse of the left mainstem bronchus (arrows) during expiration. (e) An animated GIF file shows dynamic left mainstem bronchus collapse during expiration. (f) Axial contrast-enhanced CT image depicts the left mainstem bronchus (arrow) compressed between the descending thoracic aorta and pulmonary artery.

 

Figure 1F
View larger version (65K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 1f:  Images from cine CT of 1-year-old girl with complex congenital heart disease including ventricular septal defect, hypoplastic aortic arch, and midline descending thoracic aorta, who presented with recurrent respiratory distress. Coronal (a, b) and volume-rendered (c, d) CT images obtained during inspiration (a, c) and expiration (b, d) demonstrate collapse of the left mainstem bronchus (arrows) during expiration. (e) An animated GIF file shows dynamic left mainstem bronchus collapse during expiration. (f) Axial contrast-enhanced CT image depicts the left mainstem bronchus (arrow) compressed between the descending thoracic aorta and pulmonary artery.

 
Fetal MR imaging is increasingly requested to screen for airway compromise in fetuses with congenital vascular malformations (Fig 2), teratomas of the neck and mediastinum, or congenital high airway obstruction syndrome. This procedure helps select a subgroup of fetuses that might benefit from aggressive airway management at birth, including ex utero intrapartum treatment or the extracorporeal membrane oxygenation procedure. Ex utero intrapartum treatment is an extension of a standard caesarean section, in which an opening is made at the midline of the anesthetized mother’s abdomen and uterus. The baby is partially delivered through the opening but remains attached by its umbilical cord to the placenta while a surgeon establishes an airway. Once the airway is secured, the umbilical cord is cut and clamped and the infant is fully delivered (6).


Figure 2A
View larger version (111K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2a:  Lymphatic malformation. Fetal MR images at the level of the fetal neck (a, b) illustrate a multicystic mass lesion (thick arrow) displacing and mildly distorting the tracheoesophageal bright spot (thin arrow) and crossing the midline from left to right. Because of the mass effect on the trachea, the birth was accomplished with an ex utero intrapartum treatment approach to ensure an adequate airway prior to cutting the umbilical cord. (c, d) MR imaging of the neck 2 months after birth. (c) Axial T2- weighted image and (d) postcontrast T1-weighted image with fat suppression show a huge left neck mass with persistent mild mass effect on the subglottic airway (thin arrows). Multiple internal septations (double arrows) and fluid-fluid levels (thick arrow) are present. The mass is predominantly nonenhancing but has multiple enhancing septations.

 

Figure 2B
View larger version (115K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2b:  Lymphatic malformation. Fetal MR images at the level of the fetal neck (a, b) illustrate a multicystic mass lesion (thick arrow) displacing and mildly distorting the tracheoesophageal bright spot (thin arrow) and crossing the midline from left to right. Because of the mass effect on the trachea, the birth was accomplished with an ex utero intrapartum treatment approach to ensure an adequate airway prior to cutting the umbilical cord. (c, d) MR imaging of the neck 2 months after birth. (c) Axial T2- weighted image and (d) postcontrast T1-weighted image with fat suppression show a huge left neck mass with persistent mild mass effect on the subglottic airway (thin arrows). Multiple internal septations (double arrows) and fluid-fluid levels (thick arrow) are present. The mass is predominantly nonenhancing but has multiple enhancing septations.

 

Figure 2C
View larger version (105K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2c:  Lymphatic malformation. Fetal MR images at the level of the fetal neck (a, b) illustrate a multicystic mass lesion (thick arrow) displacing and mildly distorting the tracheoesophageal bright spot (thin arrow) and crossing the midline from left to right. Because of the mass effect on the trachea, the birth was accomplished with an ex utero intrapartum treatment approach to ensure an adequate airway prior to cutting the umbilical cord. (c, d) MR imaging of the neck 2 months after birth. (c) Axial T2- weighted image and (d) postcontrast T1-weighted image with fat suppression show a huge left neck mass with persistent mild mass effect on the subglottic airway (thin arrows). Multiple internal septations (double arrows) and fluid-fluid levels (thick arrow) are present. The mass is predominantly nonenhancing but has multiple enhancing septations.

 

Figure 2D
View larger version (106K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2d:  Lymphatic malformation. Fetal MR images at the level of the fetal neck (a, b) illustrate a multicystic mass lesion (thick arrow) displacing and mildly distorting the tracheoesophageal bright spot (thin arrow) and crossing the midline from left to right. Because of the mass effect on the trachea, the birth was accomplished with an ex utero intrapartum treatment approach to ensure an adequate airway prior to cutting the umbilical cord. (c, d) MR imaging of the neck 2 months after birth. (c) Axial T2- weighted image and (d) postcontrast T1-weighted image with fat suppression show a huge left neck mass with persistent mild mass effect on the subglottic airway (thin arrows). Multiple internal septations (double arrows) and fluid-fluid levels (thick arrow) are present. The mass is predominantly nonenhancing but has multiple enhancing septations.

 

   Classification of Disorders Causing Tracheobronchial Airway Compromise in Children
Top
 Abstract
 Learning Objectives:
 Introduction
 Clinical Manifestations
 Imaging Approach
 Classification of Disorders...
Conclusion
 References
 
Airway compromise can be either fixed or dynamic, with varying degrees of collapse during the respiratory cycle. Some lesions exhibit both components. These abnormalities are further classifiable as extrinsic (located outside the trachea and bronchi but exerting mass effect on the airway) or intrinsic (intramural and/or intraluminal). They are further classified as congenital, infectious and/or inflammatory, traumatic, vascular, or neoplastic. Table 3 outlines a systematic classification of disorders that result in airway compromise.


View this table:
[in this window]
[in a new window]

  		Table 3. Extrinsic versus Intrinsic Lesions
 
A substantial proportion of clinically significant intrinsic and extrinsic airway abnormalities are within the spectrum of congenital bronchopulmonary foregut malformations. Some of the conditions included in this spectrum are congenital pulmonary airway malformation, pulmonary sequestration, bronchogenic cyst, bronchial atresia, congenital lobar hyperinflation, pulmonary agenesis/aplasia/hypoplasia (including scimitar syndrome), tracheal and esophageal diverticula, tracheal bronchus, bronchial isomerism, esophageal duplication cysts, neuroenteric cysts, congenital esophageal stenosis and atresia, tracheal atresia and tracheoesophageal fistula (TEF), and esophageal bronchus. Newman and Langston have discussed the imaging findings and pathology of these conditions in detail (7,8).

Extrinsic Airway Obstruction
Congenital lesions.— Congenital lesions causing extrinsic airway obstruction include vascular malformations and a few conditions in the bronchopulmonary foregut malformation spectrum. With the increasing use of fetal imaging in the developed world, many of these conditions are now detected at antenatal ultrasonography (US). The degree of airway compromise can be assessed either with US or MR imaging. This information is useful in selecting an appropriate fetal delivery option.

Vascular malformations may be venous, lymphatic, or mixed venolymphatic. Although these lesions are often soft and compressible, giant malformations of the neck and/or chest can compromise the airway by mass effect (Fig 2).

Bronchogenic cysts (Fig 3) are among the most common cystic lesions in the chest. Most of them occur around the carina, but they can occur anywhere along the respiratory tract. They arise from abnormal budding of the ventral embryonic foregut, leading to a focal cystic duplication of the tracheobronchial tree lined with ciliated columnar epithelium. CT demonstrates a nonenhancing, well-defined water or soft-tissue attenuation lesion, typically residing in the posterior or middle mediastinum where it can compromise the airway (9). The dilated proximal esophageal pouch in esophageal atresia can also exert a mass effect on the airway. Tracheomalacia is commonly associated with esophageal atresia and TEFs. The mechanism of tracheomalacia in these patients is unclear, but hypotheses include tracheal compression by the dilated upper-esophageal pouch or a lack of amniotic liquid inside the trachea causing a reduction in intrafetal tracheal stenting (10).


Figure 3
View larger version (42K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 3:  Subcarinal bronchogenic cyst. Three-month-old girl with asymmetric breath sounds. (A) Chest radiograph shows hyperinflation of the left lung. (B) Coronal CT image in lung window and (C) axial contrast-enhanced CT image in mediastinal window show a cystic subcarinal lesion (*) compressing the left mainstem bronchus (arrow).

 
Infectious and/or inflammatory conditions.— Deep neck space infections, particularly when they spread into the mediastinum, can compromise the airway. Mediastinal and hilar lymphadenopathy from mycobacterial or fungal infections can narrow the airway by mass effect (Fig 4). Occasionally, these enlarged lymph nodes erode into the bronchus and result in endobronchial fibrosis or luminal occlusion.


Figure 4
View larger version (50K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 4:  Lymphadenopathy in a 5-year-old boy after heart transplantation. Contrast-enhanced axial CT images just below (A) the carina and (B) at the lower hila show subcarinal and hilar lymph node enlargement compressing the left mainstem bronchus and its proximal branches.

 
Foreign bodies.— Esophageal foreign bodies can present acutely with symptoms related to airway compromise or with complications of perforation and subsequent neck and/or mediastinal infection. Ingestion of batteries, in particular, predisposes to perforation. A high index of clinical suspicion is required, since a history of foreign body ingestion may not be witnessed or elicited from the child. Figure 5 illustrates an example of an inflammatory phlegmon due to esophageal perforation by a non-radio-opaque foreign body masquerading as a mass lesion.


Figure 5
View larger version (105K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 5:  Esophageal foreign body compromising the airway in a 2-year-old girl with dysphagia most evident with solid foods. (A) Esophagogram shows extraluminal extravasation of contrast material at the site of abrupt narrowing of the esophageal lumen. (B, C) Contrast-enhanced CT images in (B) axial and (C) coronal planes show a heterogeneously attenuating, gas-containing periesophageal mass narrowing and displacing the trachea rightward. Endoscopy revealed esophageal perforation by a star-shaped plastic toy embedded in a periesophageal inflammatory mass with erosion of the esophageal wall. (Esophagogram courtesy of Gael Lonergan, MD, Children’s Hospital of Austin, Tex.)

 
Proliferative or neoplastic lesions.— Lymphoma (Fig 6A) is the most common childhood neoplasm that causes symptomatic airway compromise in children (11). Other neoplasms that can narrow the airway by extrinsic mass effect include infantile hemangiomas (Fig 6B), rhabdomyosarcomas, neurogenic tumors, germ cell tumors, and, rarely, thyroid neoplasms (Fig 6C–6E). Substantial narrowing of the trachea or major bronchi can occur without significant compromise of breathing at rest, and the caliber of the airway should be determined with radiography or CT to evaluate the risk of life-threatening airway obstruction before any procedure requiring general anesthesia or heavy sedation in a patient with a large anterior mediastinal mass (12). Whenever possible, every attempt should be made to obtain a biopsy specimen from these lesions with use of local infiltrative anesthesia (13).


Figure 6
View larger version (105K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 6:  Extrinsic neoplastic and proliferative lesions. (A) Axial CT image depicts left mainstem bronchus compression (arrow) by mass effect due to mediastinal T-cell lymphoma. (B) Axial T1-weighted postcontrast MR image with fat saturation reveals rightward displacement of the trachea (arrow) by a hemangioma of infancy. (C–E) Five-year-old girl presenting with hemoptysis. (C) Nonenhanced and (D, E) contrast-enhanced axial CT images demonstrate heterogenously enhancing thyroid gland and irregular contour of the airway. Bronchoscopic biopsy revealed follicular variant of papillary thyroid carcinoma invading the airway.

 
Vascular Anomalies.— A vascular ring encircling the mediastinal airway results from the failure of primitive vascular structures to fuse and regress normally during the development of the aortic arch, pulmonary arteries, and ductus arteriosus. Patients with vascular rings may present with wheezing, stridor, feeding difficulties, choking episodes, or aspiration pneumonia, depending on the degree of tracheal and esophageal narrowing. The most common type of vascular ring is either a right aortic arch with an aberrant left subclavian artery and a patent ductus arteriosus/ligamentum arteriosum completing the ring (Fig 7) or a double aortic arch and its variants (Figs 8–10). In both conditions, radiography may demonstrate leftward deviation of the trachea and an indentation in the right tracheal wall. Bilateral tracheal wall indentation may sometimes be seen in double aortic arch, although it may not be symmetric. On the lateral view of the chest, a subtle anterior displacement of the tracheal air column can be present. This observation together with the finding of a right sided aortic arch on the frontal view allows the radiologist to strongly suggest the presence of a vascular ring on the basis of chest radiography alone. A double aortic arch can be either complete or incomplete, with atresia of variable portions of the left arch, most commonly involving the distal left arch (14).


Figure 7
View larger version (109K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 7:  Vascular ring–right aortic arch with aberrant left subclavian artery in a 16-year-old girl with a cardiac murmur. (A–C) Axial T1-weighted MR images demonstrate a right aortic arch with an aberrant left subclavian artery. There is narrowing and displacement of the trachea (solid arrow) by mass effect from a retroesophageal aortic diverticulum (dotted arrow). (D, E) Three-dimensional volume-rendered contrast-enhanced MR angiography demonstrates the right aortic arch with aberrant left subclavian artery arising from the retroesophageal aortic diverticulum.

 

Figure 8
View larger version (119K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 8:  Vascular ring–double aortic arch with atretic left arch. (A, B) Esophagograms show posterior impression on the esophagus (arrow). (C) Coronal and (D, E) axial T1 weighted MR images and (F) 3D volume-rendered MR image in posterior projection demonstrate a double aortic arch with an atretic left arch causing tracheal narrowing and deviation (thick arrows). The small retroesophageal diverticulum (thin arrows) represents a remnant of the atretic left arch.

 

Figure 9
View larger version (86K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 9:  Vascular ring–double aortic arch. (A) Chest radiograph shows focal indentation and narrowing of the midline trachea (arrow). (B, C) Anteroposterior and lateral esophagograms show circumferential narrowing of the esophageal lumen (arrows). The esophagus is slightly displaced to the left. (D) Three-dimensional volume-rendered image from contrast-enhanced MR angiography demonstrates a double aortic arch (arrows). (E–G) Axial gradient-echo MR images show the double aortic arch, the typical parallel arrangement of the major aortic branch vessels bilaterally, and moderate narrowing of the tracheal lumen (arrows).

 

Figure 10
View larger version (137K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 10:  Vascular ring. Coronal T1-weighted MR images show a double aortic arch (A) before and (B) after surgical repair of the vascular ring. Tracheal narrowing at the level of the vascular ring resolves after surgery.

 
Contrast esophagography cannot reliably distinguish among the types of vascular ring. Cross-sectional imaging, either with CT or MR, is helpful in delineating the anatomy and aiding surgical planning for thoracoscopy or an open thoracotomy. An aberrant left pulmonary artery arising from the right pulmonary artery, or pulmonary artery sling (Figs 11,12), is another vascular cause of airway compromise. In this condition, the left pulmonary artery arises from the right pulmonary artery, hooks around the carina just above the takeoff of the right mainstem bronchus, and crosses the mediastinum between the esophagus and the trachea to the left hilum. This course of the left pulmonary artery results in characteristic posterior tracheal and anterior esophageal indentations on the contrast material column during esophagography, which sometimes can be seen on lateral chest radiographs (Fig 11). Impingement of the aberrant left pulmonary artery on the right mainstem bronchus can result in either right lung hypoaeration or air trapping. The ring-sling complex (Fig 12) has been defined as the association of an aberrant left pulmonary artery with complete cartilaginous tracheal rings and tracheal stenosis. Again, cross-sectional imaging with CT or MR is helpful in presurgical planning and postsurgical assessment (15,16). Other vascular causes of airway compromise are rare. Figures 1 illustrates a midline descending thoracic aorta, crossing from left to right in the midthorax, resulting in extrinsic compression of the left mainstem bronchus.


Figure 11
View larger version (60K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 11:  Pulmonary sling. (A) Anteroposterior and (B) lateral chest radiographs show inverted T-shape of the trachea (arrow in A) and mainstem bronchi and a posterior impression on the distal trachea (arrow in B).

 

Figure 12
View larger version (79K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 12:  Pulmonary sling associated with tracheal ring. (A, B) Axial T1-weighted MR images show aberrant origin of the left pulmonary artery (solid arrow) arising from the right pulmonary artery, with the left pulmonary artery coursing between the narrowed distal trachea and esophagus. The axial images also show the presence of complete cartilaginous tracheal rings (dashed arrows). (C) T1-weighted coronal MR image demonstrates narrowing of the distal trachea. (D) Three-dimensional volume-rendered image from contrast-enhanced MR angiography, in posterior projection, shows stenosis of the proximal left pulmonary artery (arrow).

 
Intrinsic Airway Obstruction
Congenital lesions.— While bronchopulmonary foregut malformations can become evident at any time, including in adulthood, they are increasingly detected prenatally owing to the increasing use of antenatal US. In older children and adults, they can be an incidental finding on a chest radiograph obtained for recurrent or nonresolving pneumonia. Bronchial atresia most commonly involves the left upper lobe. At CT (Fig 13), a mucocele is identified as a hypoattenuating branching structure distal to the atretic bronchus near the hilum. At times, the accompanying bronchial arteries can be identified. The pulmonary parenchyma distal to the atretic segment often demonstrates air trapping owing to maldevelopment of the peripheral air spaces, and the affected region may be outlined by pseudofissures. Figure 14 demonstrates left-sided proximal bronchial narrowing, with similar maldevelopment of the lung parenchyma but without an associated mucocele. Bronchial atresia may be isolated or associated with a retained systemic vascular connection. According to Langston (8), the bronchial atresia associated with a retained systemic vascular connection (intralobar sequestration) is virtually identical in appearance to that of isolated bronchial atresia, except that the atretic bronchus is ectopically located at the margin of the lung. Rarely, such ectopic bronchi are not atretic but have a connection with the gastrointestinal tract, usually the esophagus (Fig 15). This is usually accompanied by dilated airways and accumulated secretions from impaired clearance of lung parenchyma. Owing to the high frequency of associated lesions, it is important to look for airway abnormalities, pulmonary parenchymal abnormalities, retained systemic vascular connections, anomalous pulmonary venous drainage, and airway communication with the gastrointestinal tract in patients with suspected bronchopulmonary foregut malformations (7,8).


Figure 13
View larger version (59K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 13:  Bronchial atresia with a mucocele distal to the atretic bronchus in a 5-year-old girl with persistent left upper lobe pneumonia. (A) CT topogram demonstrates left suprahilar opacity (arrow). (B, C) Axial contrast-enhanced CT images in mediastinal windows show a low-attenuation paramediastinal mass at the left upper lobe (dotted arrow), representing a mucocele distal to the atretic bronchus. A vessel medial to the cystic mass (solid arrow in B) represents the bronchial artery branch accompanying the mucocele. A small diverticulum representing the proximal segment of the atretic bronchus is also depicted (arrow in C). (D, E) Axial CT images in lung windows demonstrate air trapping in the left upper lobe surrounding the mucocele (arrow). Pathologic examination of the left upper lobectomy specimen confirmed a large left upper lobe mucocele contiguous with an atretic superior division bronchus.

 

Figure 14
View larger version (78K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 14:  Congenital lung malformation with proximal bronchial narrowing. (A) Axial CT in lung window shows air trapping in much of the left lung parenchyma with multiple cystic areas. (B) Virtual bronchoscopy image shows narrowing of the left mainstem bronchus (arrow). (C) Three-dimensional volume-rendered image demonstrates narrowing of the left mainstem bronchus (arrows), air trapping resulting in hyperinflation of much of the left lung, and several small parenchymal cysts. Histopathologic examination revealed maldeveloped lung with proximal bronchial obstruction.

 

Figure 15
View larger version (81K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 15:  Esophageal bronchus in a neonate with respiratory distress. (A) Coronal and (B) axial CT images in lung windows show an esophageal bronchus (white arrows) associated with the right lower lung. The right lung is small and almost completely opacified, particularly the lower lobe (black arrows). (C) Esophagogram confirms the presence of the esophageal bronchus (arrow). At surgery, the right middle lobe and lower lobe were noted to communicate with the esophageal bronchus as part of a bronchopulmonary foregut malformation. Pathologic examination revealed poor alveolar development, mucus stasis, and obliterative bronchiolitis.

 
Esophageal atresia with or without TEF is believed to result from a faulty separation of the primitive embryonic trachea and esophageal remnants. The most common type of these anomalies is proximal esophageal atresia with distal TEF (up to 80%–90%). H-shaped TEFs with no atresia comprise up to 5%–8%. Other types include proximal esophageal atresia with combined proximal and distal TEF (1%–3%) and proximal esophageal atresia with proximal TEF (1%). The remaining 8% of cases are isolated esophageal atresia without TEF. They are frequently associated with trisomy 18, trisomy 21, and the VATER/VACTERL constellation of anomalies (vertebral, anal, and cardiac abnormalities, TEF, esophageal atresia, and renal and limb abnormalities). Typical clinical presentation includes failure to pass a transesophageal catheter into the stomach in a newborn with a history of polyhydramnios at prenatal US, excessive secretions from the mouth, and respiratory distress. Chest radiography demonstrates the transesophageal catheter ending in the proximal thoracic esophagus. The presence of air in the distal gastrointestinal tract confirms the presence of a distal TEF (Fig 16). In such patients, it is important to observe the airway on the upper gastrointestinal series or at esophagography for frequently associated tracheomalacia (17).


Figure 16
View larger version (28K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 16:  Esophageal atresia with a distal TEF in a newborn girl with a history of polyhydramnios at prenatal US, respiratory distress, copious secretions in the mouth, and inability to pass transesophageal catheter into the stomach. Anteroposterior radiograph of the chest and abdomen illustrates a transesophageal catheter ending in the proximal thoracic esophagus (arrow). Distal TEF is suggested by the presence of air in the stomach and in bowel loops in the abdomen.

 
Congenital tracheal stenosis is characterized by tracheal narrowing due to complete or near complete cartilaginous tracheal rings. Described patterns of tracheal stenosis include generalized stenosis, carrot- or funnel-shaped segmental stenosis, and focal stenosis. Focal or segmental stenosis usually involves the lower trachea. In rare cases, there may be a cartilaginous sleeve rather than distinct cartilaginous rings. Since resistance to laminar airflow increases linearly with the length of the stenosis and with the fourth power of the reduction in diameter, tight stenosis causes more severe symptoms than a long, mild stenosis. Congenital complete tracheal rings (Fig 17) may occur independently or may be associated with a pulmonary sling. Circumferential narrowing of the entire length of the trachea, fusion of the cartilaginous tracheal rings posteriorly, or the absence of the posterior membranous wall (O-shaped trachea on an axial section) are the typical imaging findings (18). Congenital tracheal stenosis is also associated with other congenital conditions such as congenital heart disease, TEF, and skeletal abnormalities. Conventional treatment includes various types of tracheoplasty, with or without interposition of cartilage, periosteum, or pericardium, or tracheal resection and primary reanastomosis. Kim et al have reported successful treatment of congenital tracheal stenosis with balloon-assisted posterior tracheal splitting and temporary placement of a covered retrievable self-expandable metallic stent (19). Congenital tracheal web is a rare entity, usually presenting with stridor, wheezing, and recurrent respiratory infections. The web is not associated with deformity of the tracheal cartilage or the tracheal wall, and CT demonstrates a weblike structure traversing and narrowing the tracheal lumen (20,21). Coronal reformatted images and virtual bronchoscopy are best for depicting the tracheal web (Fig 18). Endoscopic argon laser treatment of tracheal webs with resolution of symptoms and normalization of pulmonary function tests has been described by Legasto et al (20).


Figure 17
View larger version (102K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 17:  Complete tracheal rings. (A) Chest radiograph shows generalized narrowing of the trachea (arrow). (B) Axial and (C) coronal electrocardiogram- and respiratory-triggered spin-echo and (D) sagittal T2-weighted MR images depict circumferential narrowing of the trachea. The tracheal cartilage (arrow in B) is O-shaped instead of the normal inverted U shape, and there is diffuse narrowing of the tracheal lumen (arrows in C and D).

 

Figure 18A
View larger version (71K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 18a:  Tracheal web in 2-year-old boy with history of noisy breathing since birth. (a) Coronal CT image, (b) 3D volume-rendered image, and (c) paused virtual bronchoscopic image just above the carina demonstrate focal narrowing of the trachea immediately above the carina. A ledge of soft tissue is seen extending from the left lateral tracheal wall (arrows in a, b; long arrows in c, d) and resulting in narrowing of the origin of the left mainstem bronchus. A smaller ledge (short arrow in c, d) is seen extending from the right lateral tracheal wall. (d) Bronchoscopy confirmed the presence of tracheal web just above the carina, narrowing the tracheal lumen to 10%–20% of its normal cross-sectional area. (e) Movie clip (http://radiographics.rsnajnls.org/cgi/content/full/e29/DC1) from virtual bronchoscopy better illustrates the tracheal web. It starts at the level of the glottis, traverses the region of the membranous tracheal web just above the carina and then enters the narrowed origin of the left main bronchus. The clip ends in the proximal left main bronchus.

 

Figure 18B
View larger version (71K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 18b:  Tracheal web in 2-year-old boy with history of noisy breathing since birth. (a) Coronal CT image, (b) 3D volume-rendered image, and (c) paused virtual bronchoscopic image just above the carina demonstrate focal narrowing of the trachea immediately above the carina. A ledge of soft tissue is seen extending from the left lateral tracheal wall (arrows in a, b; long arrows in c, d) and resulting in narrowing of the origin of the left mainstem bronchus. A smaller ledge (short arrow in c, d) is seen extending from the right lateral tracheal wall. (d) Bronchoscopy confirmed the presence of tracheal web just above the carina, narrowing the tracheal lumen to 10%–20% of its normal cross-sectional area. (e) Movie clip (http://radiographics.rsnajnls.org/cgi/content/full/e29/DC1) from virtual bronchoscopy better illustrates the tracheal web. It starts at the level of the glottis, traverses the region of the membranous tracheal web just above the carina and then enters the narrowed origin of the left main bronchus. The clip ends in the proximal left main bronchus.

 

Figure 18C
View larger version (121K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 18c:  Tracheal web in 2-year-old boy with history of noisy breathing since birth. (a) Coronal CT image, (b) 3D volume-rendered image, and (c) paused virtual bronchoscopic image just above the carina demonstrate focal narrowing of the trachea immediately above the carina. A ledge of soft tissue is seen extending from the left lateral tracheal wall (arrows in a, b; long arrows in c, d) and resulting in narrowing of the origin of the left mainstem bronchus. A smaller ledge (short arrow in c, d) is seen extending from the right lateral tracheal wall. (d) Bronchoscopy confirmed the presence of tracheal web just above the carina, narrowing the tracheal lumen to 10%–20% of its normal cross-sectional area. (e) Movie clip (http://radiographics.rsnajnls.org/cgi/content/full/e29/DC1) from virtual bronchoscopy better illustrates the tracheal web. It starts at the level of the glottis, traverses the region of the membranous tracheal web just above the carina and then enters the narrowed origin of the left main bronchus. The clip ends in the proximal left main bronchus.

 

Figure 18D
View larger version (130K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 18d:  Tracheal web in 2-year-old boy with history of noisy breathing since birth. (a) Coronal CT image, (b) 3D volume-rendered image, and (c) paused virtual bronchoscopic image just above the carina demonstrate focal narrowing of the trachea immediately above the carina. A ledge of soft tissue is seen extending from the left lateral tracheal wall (arrows in a, b; long arrows in c, d) and resulting in narrowing of the origin of the left mainstem bronchus. A smaller ledge (short arrow in c, d) is seen extending from the right lateral tracheal wall. (d) Bronchoscopy confirmed the presence of tracheal web just above the carina, narrowing the tracheal lumen to 10%–20% of its normal cross-sectional area. (e) Movie clip (http://radiographics.rsnajnls.org/cgi/content/full/e29/DC1) from virtual bronchoscopy better illustrates the tracheal web. It starts at the level of the glottis, traverses the region of the membranous tracheal web just above the carina and then enters the narrowed origin of the left main bronchus. The clip ends in the proximal left main bronchus.

 
Tracheobronchial branching anomalies can be seen as an isolated finding or accompanying heterotaxy syndromes, pulmonary sling, and conditions associated with pulmonary underdevelopment (agenesis and aplasia), including the scimitar syndrome (Fig 19). Abnormal branching patterns include bilateral right-sided isomerism (Fig 20A, 20B), bilateral left-sided isomerism (Fig 20C), tracheal bronchus, accessory cardiac bronchus, and tracheal diverticulum (Fig 21). A tracheal bronchus arises from the trachea or mainstem bronchus and can aerate the entire upper lobe or a segment. The tracheal bronchus is further divided into either displaced or supernumerary types (with or without a blind ending), depending on the presence or absence of the normal branching pattern of the right mainstem bronchus (22). An accessory cardiac bronchus arises from the medial wall of the right mainstem bronchus or bronchus intermedius opposite the origin of the right upper lobe bronchus, grows toward the pericardium, and terminates as a blind-ending stump or branches farther into vestigial or rudimentary bronchial tissue (23). Tracheal diverticula are most commonly seen arising with a narrow stalk from the right posterolateral wall of the trachea near the thoracic inlet (24).


Figure 19
View larger version (116K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 19:  Hypoplastic right lung with anomalous tracheal branching. (A) Anteroposterior chest radiograph and (B) axial CT image demonstrate the hypoplastic right lung, dextropositioned heart, and horseshoe lung (arrow in B). (C) Three-dimensional volume-rendered image shows the horseshoe lung (long arrow), stenotic origin of the right upper lobe bronchus from the trachea (short arrow), and stenosis of the bronchus intermedius and left main bronchus distal to the tracheal bifurcation (dashed arrows). These findings along with anomalous pulmonary venous drainage (not shown) are consistent with the scimitar syndrome. (D) Three-dimensional volume-rendered image after surgical repair shows widely patent right upper lobe bronchus arising from the trachea (short arrow) and the right lower lobe bronchus and left main bronchus (dashed arrows). Anomalous medial branches (long arrow) from the right lower lobe bronchus are associated with the medial left basilar portion of the horseshoe lung. Note: The previously aerated bridging midline (horseshoe) lung parenchyma showed consolidation on the axial CT images (not shown) and hence is not visualized on the volume-rendered images.

 

Figure 20
View larger version (37K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 20:  Bronchial isomerism. (A, B) Right bronchial isomerism with symmetric eparterial bronchi (thick arrows) bilaterally. The thin arrow in A indicates the right pulmonary artery, and the thin arrow in B indicates the left pulmonary artery. (C) Left bronchial isomerism with symmetric hyparterial bronchi (thick arrows) bilaterally. The thin arrows indicate right and left pulmonary arteries.

 

Figure 21
View larger version (59K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 21:  Tracheal diverticulum. (A) Coronal and (B) axial noncontrast CT images depict a diverticulum with a narrow stalk (arrows) arising from the posterolateral wall of the trachea near the level of the thoracic inlet.

 
Inflammatory and/or infectious conditions.— Croup, or laryngotracheobronchitis (Fig 22A, 22B), is an acute viral lower respiratory infection commonly seen in children aged 6 months to 3 years. Patients with viral croup present with inspiratory stridor accompanied by low-grade fever and upper respiratory symptoms. Radiography classically demonstrates hypopharyngeal overdistention and subglottic airway narrowing. In several locales, bacterial tracheitis has re-emerged as a primary cause of acute, life-threatening upper airway infection, and it should be suspected in patients who have symptoms similar to croup but who demonstrate more toxicity or who are refractory to croup treatment. Subglottic airway narrowing is common in bacterial tracheitis, as with croup, and the identification of intraluminal tracheal membranes or tracheal wall irregularity at airway radiography (Fig 23) helps distinguish bacterial tracheitis from croup (25–28).


Figure 22
View larger version (85K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 22:  Croup. (A) Lateral and (B) anteroposterior radiographs of the neck show symmetric narrowing of the subglottic airway and upper trachea.

 

Figure 23
View larger version (79K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 23:  Exudative bacterial tracheitis. (A) Lateral and (B) anteroposterior radiographs of the upper airway show airway wall irregularity and intraluminal membranes (arrows) along the subglottic airway and cervical trachea.

 
Relapsing polychondritis is a rare multisystemic disease characterized by recurrent inflammation of the cartilaginous structures of the ear, nose, joints, larynx, and tracheobronchial tree. Respiratory tract involvement occurs in up to half of patients during the course of the illness. Airway involvement is a poor prognostic sign and is the leading cause of death in affected patients. CT findings include fixed airway lumen narrowing and airway wall thickening with or without calcification (Fig 24). The finding of smooth anterior and lateral airway wall thickening with sparing of the posterior membranous wall is highly suggestive of relapsing polychondritis and is thought to be attributable to cartilaginous destruction and fibrosis (29,30). Airway malacia and air trapping precede the fibrosis, explaining the higher sensitivity of expiratory CT than that of routine inspiratory CT for airway abnormalities in patients with relapsing polychondritis (29).


Figure 24
View larger version (45K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 24:  Relapsing polychondritis in a 15-year-old boy. (A, B) Axial contrast-enhanced CT images in mediastinal windows at different anatomic levels show tracheobronchial wall calcifications and wall thickening (arrows) with sparing of the posterior membranous portion of the trachea.

 
Metabolic Conditions
Hunter syndrome is a mucopolysaccharidosis characterized by deficiency of iduronate sulfatase, leading to progressive accumulation of dermatan sulfate and heparin sulfate in various tissues, including the respiratory tract. The deposition of the mucopolysaccharides in the walls of the major airways results in progressive airway narrowing due to wall thickening and anteroposterior collapse (Fig 25). Davitt et al have reported using tracheobronchial stenting in the treatment of major airway obstruction in a patient with Hunter syndrome (31).


Figure 25
View larger version (77K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 25:  Hunter syndrome in a 16-year-old patient. (A) Sagittal and (B, C) axial CT images show severe anteroposterior flattening of the trachea (arrows) related to mucopolysaccharide infiltration.

 
Posttraumatic Conditions
Direct trauma can result in cartilaginous damage and occlusion of the airway lumen by hemorrhage or airway collapse. Prolonged intubation can lead to both airway malacia and airway stenosis, particularly with oversized endotracheal tubes or balloon cuffs. Airway stenosis consequent to prolonged intubation is usually at the level of cricoid cartilage (the narrowest part of the upper airway) (25). Plain radiography can establish the diagnosis, although cross-sectional imaging with CT or MR imaging better depicts the length of the involved segment and the degree of stenosis (Fig 26A–26C). The stenosis may be associated with granuloma formation, especially in the subacute stage, and mimic a mass lesion, prompting biopsy (Fig 26D). Postoperative infection, especially fungal, and prolonged mechanical ventilation are risk factors for the development of airway stenosis at sites of bronchial anastomosis in lung transplant patients. Such stenoses are amenable to diagnosis with CT if not detected during posttransplant bronchoscopic surveillance (32).


Figure 26
View larger version (81K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 26:  (A–C) Postintubation stricture and granulation tissue in 11-year-old girl with history of prolonged intubation for pneumonia. (A) Axial CT in lung window and (B, C) 3D volume-rendered CT images of the airway demonstrate tracheal stenosis (arrows). (D) Postintubation intratracheal granulation tissue in an 8-year-old boy with progressive stridor since a difficult emergency intubation 2 months previously. Lateral neck radiograph shows two nodular soft-tissue masses (arrows) in the subglottic region. Bronchoscopy revealed airway stenosis due to subglottic granulation tissue.

 
Foreign Body Aspiration
Prompt diagnosis and safe retrieval of an airway foreign body is still a challenging task despite technologic advances in both imaging and endoscopy. The typical patient is a child 1–3 years of age, with an unwitnessed aspiration episode and with symptoms and signs that can mimic asthma, upper respiratory infection, or pneumonia. The most commonly aspirated airway foreign bodies are food products, particularly nuts, beans, and seeds, which are not sufficiently radio-opaque to be identified at conventional radiography. The absorption of water by these organic materials can rapidly change a partial airway obstruction to a complete airway obstruction. True expiratory radiographs are difficult to obtain in infants and young children, and decubitus radiography and airway fluoroscopy are helpful in this setting for revealing air trapping due to the ball-valve effect of an endobronchial foreign body (Fig 27A, 27B). Metallic foreign bodies can be easily identified on plain radiographs (Fig 27C, 27D). Endoscopy should be performed if the clinical suspicion for an airway foreign body is high, even if chest radiography or fluoroscopy have negative results, since their sensitivity for an airway foreign body is modest. A CT scan of the chest is a reasonable option for investigation of an airway foreign body if the clinical setting does not strongly warrant bronchoscopy or if bronchoscopy is not readily available and fluoroscopic findings are equivocal (33–35). The most reliable CT finding of an aspirated foreign body is identification of opaque or nonopaque endobronchial foreign body. CT also helps identify the resulting obstructive or reactive changes within the distal airway and lung parenchyma, such as retained secretions, bronchiectasis, hyperaeration, atelectasis, and parenchymal cavitation. Kosucu et al found a 100% sensitivity and specificity for CT in the evaluation of endobronchial foreign bodies (34). Applegate et al reported that low-dose helical CT has a sensitivity of 83% and specificity of 89% for visualizing plastic pieces in the airway. However, peanuts were not well visualized in the same study (36).


Figure 27
View larger version (95K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 27:  (A, B) Nonopaque foreign body in 21-month-old patient who choked while eating an apple. (A) Frontal and (B) right lateral decubitus chest radiographs show asymmetric hyperlucency of the right lower lung with air trapping exaggerated in the right lateral decubitus view. Bronchoscopy confirmed an aspirated foreign body in the right mainstem bronchus. (C, D) Radio-opaque foreign body in 15-month-old boy with stridor after swallowing a button 2 hours previously. (C) Lateral view of the neck and (D) bronchoscopy show a button in the glottic airway.

 
Proliferative or Neoplastic Disease
Endotracheal and endobronchial tumors are rare in the pediatric population but should be considered in addition to airway foreign bodies in the differential diagnosis of persistent abnormalities at chest radiography. The most common of these tumors are hemangioma, bronchial carcinoid, and squamous papilloma in the setting of juvenile-onset recurrent respiratory papillomatosis. Rarer lesions include adenoid cystic carcinoma, mucoepidermoid carcinoma, myofibroblastic tumor, juvenile xanthogranuloma, and metastasis.

Hemangiomas are potentially life-threatening when in a subglottic location, particularly during the proliferative phase of the tumor. In the proliferative phase, hemangioma characteristically appears at CT as a uniformly enhancing soft-tissue mass (Fig 28). Similarly, homogeneous contrast enhancement and increased signal intensity on T2-weighted images with multiple flow voids are findings that characterize hemangioma in the proliferative phase on MR images. In the involuting phase, enhancement is variable and fibrofatty infiltration may be seen. Spontaneous regression is typical. When expectant management is not a prudent option, as in patients with significant and symptomatic airway compromise, treatment options include systemic or intralesional corticosteroid injection, laser ablation, interferon, and surgical excision (37,38).


Figure 28
View larger version (102K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 28:  Infantile hemangioma in a 6-month-old girl with stridor. (A) Contrast-enhanced axial CT of the neck shows an intensely enhancing mass lesion along the posterior wall of the subglottic airway (arrow). (B) Photomicrograph of the tumor shows a compact proliferation of capillary-sized vessels entrapping the tracheal mucus glands. (Hematoxylin-eosin stain; original magnification, x10.) (C) Photomicrograph from Glut-1 immunohistochemistry for glucose transporter type 1 shows strong endothelial positivity, characteristic of infantile hemangioma. (Original magnification, x20.)

 
Juvenile xanthogranuloma (Fig 29) of the airway is rare but can result in severe respiratory compromise. A form of non–Langerhans cell histiocytosis in children, juvenile xanthogranuloma usually presents with cutaneous lesions in the 1st year of life. Visceral involvement is rare and is usually associated with cutaneous lesions. Many of these lesions regress spontaneously, and treatment is required only in the case of potential compromise of vital structures. Treatment options include endoscopic or surgical excision (39).


Figure 29A
View larger version (72K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 29a:  Juvenile xanthogranuloma in a 7-month-old boy with stridor since the age of 2 weeks. (a) (A) Anteroposterior and (B) lateral radiographs of the neck show an intratracheal mass (arrows). (C) Axial and (D) sagittal contrast-enhanced CT images show a mildly enhancing mass protruding from the right tracheal wall (arrows). (b) (E, F) Photomicrographs (hematoxylin-eosin stain; E, original magnification, x4; F, original magnification, x20) show the lesion is composed of a cellular histiocytic proliferation below the mucosal surface. The histiocytes are focally enlarged with clear foamy cytoplasm, and occasional multinucleate Touton-type giant cells are noted. (Courtesy of Karen W. Eldin, MD, Department of Pathology, Texas Children’s Hospital, Houston, Tex.)

 

Figure 29B
View larger version (84K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 29b:  Juvenile xanthogranuloma in a 7-month-old boy with stridor since the age of 2 weeks. (a) (A) Anteroposterior and (B) lateral radiographs of the neck show an intratracheal mass (arrows). (C) Axial and (D) sagittal contrast-enhanced CT images show a mildly enhancing mass protruding from the right tracheal wall (arrows). (b) (E, F) Photomicrographs (hematoxylin-eosin stain; E, original magnification, x4; F, original magnification, x20) show the lesion is composed of a cellular histiocytic proliferation below the mucosal surface. The histiocytes are focally enlarged with clear foamy cytoplasm, and occasional multinucleate Touton-type giant cells are noted. (Courtesy of Karen W. Eldin, MD, Department of Pathology, Texas Children’s Hospital, Houston, Tex.)

 
Inflammatory myofibroblastic tumor, previously called inflammatory pseudotumor, consists of a variable mixture of collagen, inflammatory cells, and spindle cells showing myofibroblastic differentiation. Found most frequently in the lung, it can occur anywhere in the body. When the tumor is in an endotracheal or endobronchial location, CT demonstrates a well-circumscribed, enhancing, and nodular or polypoid mass lesion (Fig 30). Calcifications may be present. The lesion has a propensity to recur, particularly after bronchoscopic removal or when the lesion is resected with only a narrow margin of normal tissue (40,41).


Figure 30A
View larger version (101K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 30a:  Bronchial inflammatory myofibroblastic tumor in a 4-year-old boy with recurrent episodes of cough and fever. (a)(A) Anteroposterior radiograph of the chest demonstrates right upper lobe volume loss (black arrow) and a lobulated opacity at the hilum, causing a "reverse S sign" suggesting a right hilar mass (white arrow). (B) Bronchoscopy revealed a mass (arrow) protruding from the orifice of the right upper lobe bronchus into the right mainstem bronchus and bronchus intermedius. The mass was partially resected. (C) Axial and (D) coronal contrast-enhanced CT images obtained 5 months later demonstrate a recurrent hilar mass (white arrows) occluding the right upper lobe bronchus, resulting in atelectasis of the right upper lobe (black arrow), and protruding into the right mainstem bronchus and bronchus intermedius. (b) (E) Photograph of right upper lobectomy specimen shows a firm, whorled, pale-tan spherical mass infiltrating the bronchial wall and protruding into the lumen proximally. (F, G) Photomicrographs (hematoxylin-eosin stain; F, original magnification, x2; G, original magnification, x20) show that (F) the tumor fills the bronchial lumen and is adherent to the bronchial wall, infiltrating the submucosa, and (G) is composed of bland spindled cells with scattered lymphocytes and rare eosinophils in the background.

 

Figure 30B
View larger version (111K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 30b:  Bronchial inflammatory myofibroblastic tumor in a 4-year-old boy with recurrent episodes of cough and fever. (a)(A) Anteroposterior radiograph of the chest demonstrates right upper lobe volume loss (black arrow) and a lobulated opacity at the hilum, causing a "reverse S sign" suggesting a right hilar mass (white arrow). (B) Bronchoscopy revealed a mass (arrow) protruding from the orifice of the right upper lobe bronchus into the right mainstem bronchus and bronchus intermedius. The mass was partially resected. (C) Axial and (D) coronal contrast-enhanced CT images obtained 5 months later demonstrate a recurrent hilar mass (white arrows) occluding the right upper lobe bronchus, resulting in atelectasis of the right upper lobe (black arrow), and protruding into the right mainstem bronchus and bronchus intermedius. (b) (E) Photograph of right upper lobectomy specimen shows a firm, whorled, pale-tan spherical mass infiltrating the bronchial wall and protruding into the lumen proximally. (F, G) Photomicrographs (hematoxylin-eosin stain; F, original magnification, x2; G, original magnification, x20) show that (F) the tumor fills the bronchial lumen and is adherent to the bronchial wall, infiltrating the submucosa, and (G) is composed of bland spindled cells with scattered lymphocytes and rare eosinophils in the background.

 
Carcinoid tumors (Fig 31) comprise approximately 80% of endobronchial neoplasms in children and adolescents. Most carcinoid tumors occur in the mainstem or lobar bronchi, and patients typically present with dyspnea, wheezing, cough, and hemoptysis. At CT, these are typically avidly enhancing, ovoid lesions with a long axis parallel to the bronchovascular bundle. They may have intraluminal, mural, and extrabronchial components. Associated collapse, consolidation, or air trapping are readily identified with CT. They are relatively slow growing, and complete surgical resection offers the best chance of cure. Surgical treatment options include bronchotomy with tumor excision, sleeve resection, lobectomy, or pneumonectomy (42,43).


Figure 31A
View larger version (117K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 31a:  Bronchial carcinoid. (a)(A, B) Coronal and (D) axial contrast-enhanced CT images in mediastinal windows demonstrate an enhancing endobronchial lesion (dashed arrows) arising from the medial wall of the right mainstem bronchus and bronchus intermedius. Medial extramural extension of the lesion abuts the esophagus (solid arrow in D). The bronchus intermedius distal to the lesion is opacified with mucoid material. (C) Coronal CT image in lung window shows patent right upper lobe bronchus and postobstructive atelectasis of the medial right lung base. The patient subsequently underwent sleeve resection of the right mainstem bronchus and bronchus intermedius and airway reconstruction with anastomosis of the right middle and lower lobe bronchi to the carina and reimplantation of the right upper lobe bronchus into the trachea. (E) Photograph of specimen from bronchial sleeve resection shows a 2.7-cm polypoid tan mass adherent to the wall and filling the lumen of the right mainstem bronchus. (F, G) Photomicrographs (hematoxylin-eosin stain; F, original magnification, x2; G, original magnification, x20) of the tumor show (F) variable architecture, including sheets and cords of cells and pseudoglandular spaces and (G) uniform nuclear contours and stippled chromatin, typical of tumors with neuroendocrine differentiation. (b)(H, I) Coronal and (J, K) volume-rendered CT images obtained postoperatively demonstrate patency of the reconstructed neocarina (long arrows in I, J and K) and the reimplanted right upper lobe bronchus (short arrows in H, J and K), with no residual or recurrent tumor.

 

Figure 31B
View larger version (108K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 31b:  Bronchial carcinoid. (a)(A, B) Coronal and (D) axial contrast-enhanced CT images in mediastinal windows demonstrate an enhancing endobronchial lesion (dashed arrows) arising from the medial wall of the right mainstem bronchus and bronchus intermedius. Medial extramural extension of the lesion abuts the esophagus (solid arrow in D). The bronchus intermedius distal to the lesion is opacified with mucoid material. (C) Coronal CT image in lung window shows patent right upper lobe bronchus and postobstructive atelectasis of the medial right lung base. The patient subsequently underwent sleeve resection of the right mainstem bronchus and bronchus intermedius and airway reconstruction with anastomosis of the right middle and lower lobe bronchi to the carina and reimplantation of the right upper lobe bronchus into the trachea. (E) Photograph of specimen from bronchial sleeve resection shows a 2.7-cm polypoid tan mass adherent to the wall and filling the lumen of the right mainstem bronchus. (F, G) Photomicrographs (hematoxylin-eosin stain; F, original magnification, x2; G, original magnification, x20) of the tumor show (F) variable architecture, including sheets and cords of cells and pseudoglandular spaces and (G) uniform nuclear contours and stippled chromatin, typical of tumors with neuroendocrine differentiation. (b)(H, I) Coronal and (J, K) volume-rendered CT images obtained postoperatively demonstrate patency of the reconstructed neocarina (long arrows in I, J and K) and the reimplanted right upper lobe bronchus (short arrows in H, J and K), with no residual or recurrent tumor.

 
Dynamic Airway Compromise
Tracheobronchomalacia (Figs 1, 32) is a condition characterized by excessive airway collapsibility and is caused by increased flaccidity of the airway wall and supporting cartilage. The normal inspiratory dilation and expiratory narrowing of the intrathoracic trachea in response to differences between intrathoracic and intraluminal pressures is accentuated in tracheomalacia, so that the narrowing of the tracheal lumen is most pronounced during forced expiration, coughing, or the Valsalva maneuver. Airway malacia may be congenital and associated with disorders of cartilage maturation or anomalies such as TEF and vascular rings or slings, or acquired from prior intubation, chronic extrinsic compression, inflammation, or infection. Airway fluoroscopy in a lateral projection is the traditional radiographic method of assessing for tracheomalacia. However, bronchomalacia is difficult to determine with fluoroscopy, and controlled-ventilation CT, cine CT, or cine MR imaging are preferred methods for the evaluation of dynamic collapsibility of bronchi.


Figure 32
View larger version (110K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 32:  Severe left main bronchial narrowing by an anomalous descending thoracic aorta in a 9-month-old infant with heterotaxy and progressive stridor. (A) Anteroposterior chest radiograph shows left-sided liver. Bronchoscopy (not shown) revealed severe narrowing of the left mainstem bronchus. (B–E) Contrast-enhanced (B, C) coronal and (D, E) axial CT images demonstrate narrowing of the left mainstem bronchus (arrow) by the anomalous descending thoracic aorta that crosses from left to right in the midthorax. The obstruction of the left mainstem bronchus was relieved surgically by transecting the descending thoracic aorta below the level of the carina and anastomosing it directly to the proximal ascending aorta. (F) Postoperative 3D volume-rendered image and (G–J) contrast-enhanced (G, H) coronal and (I, J) axial CT images demonstrate resolution of the narrowing of the left mainstem bronchus (white arrow). The descending thoracic aorta now courses inferior to the carina (G). The anastomotic site between the posterior ascending aorta and the descending thoracic aorta is shown in J (black arrow). Note: Left bronchial isomerism is best depicted in F.

 

   Conclusion
Top
 Abstract
 Learning Objectives:
 Introduction
 Clinical Manifestations
 Imaging Approach
 Classification of Disorders...
 Conclusion
References
 
"Always look at the airway" is a maxim worth emphasizing in pediatric radiology. A working knowledge of the advantages and limitations of available imaging modalities, including conventional radiography, fluoroscopy, CT, and MR imaging, as well as advanced applications such as dynamic cine imaging, multiplanar reconstruction, and virtual bronchoscopy, allows selection of the most appropriate imaging sequence for the prompt, accurate, and safe depiction of airway disorders in infants and children. A broad spectrum of extrinsic and intrinsic disorders can compromise the tracheobronchial airway in children, and awareness of the characteristic clinical and imaging features of these disorders allows the differential diagnosis to be refined for planning of confirmatory diagnostic procedures and treatment.


   Footnotes
 

Abbreviations: TEF = tracheoesophageal fistula, 3D = three-dimensional


   References
Top
 Abstract
 Learning Objectives:
 Introduction
 Clinical Manifestations
 Imaging Approach
 Classification of Disorders...
 Conclusion
 References
 

  1. Vicencio AG, Parikh S. Laryngomalacia and tracheomalacia: common dynamic airway lesions. Pediatr Rev 2006;27:e33–e35.[Free Full Text]
  2. Patterson PE, Harding SM. Gastroesophageal reflux disorders and asthma. Curr Opin Pulm Med 1999;5:63–67.[CrossRef][Medline]
  3. Goo HW, Kim HJ. Detection of air-trapping on inspiratory and expiratory phase images obtained by 0.3-second cine CT in the lungs of free-breathing young children. Am J Roentgenol (AJR) 2006;187:1019–1023.[Abstract/Free Full Text]
  4. Long FR, Castile RG. Technique and clinical applications of full-inflation and end-expiration controlled-ventilation chest CT in infants and young children. Pediatr Radiol 2001;31:413–422.[CrossRef][Medline]
  5. Suto Y, Tanable Y. Evaluation of tracheal collapsibility in patients with tracheomalacia using dynamic MR imaging during coughing. Am J Roentgenol (AJR) 1998;171:393–394.[Free Full Text]
  6. Mota R, Ramalho C, Monteiro J, et al. Evolving indications for the EXIT procedure: the usefulness of combining ultrasound and fetal MRI. Fetal Diagn Ther 2007;22:107–111.[CrossRef][Medline]
  7. Newman B. Congenital bronchopulmonary foregut malformations: concepts and controversies. Pediatr Radiol 2006;36:773–791.[CrossRef][Medline]
  8. Langston C. New concepts in the pathology of congenital lung malformations. Semin Pediatr Surg 2003;12:17–37.[CrossRef][Medline]
  9. Winters WD, Effmann EL. Congenital masses of the lung: prenatal and postnatal imaging evaluation. J Thorac Imaging 2001;16:196–206.[CrossRef][Medline]
  10. Briganti V, Oriolo L, Buffa V, Garofalo S, Cavallaro S, Calisti A. Tracheomalacia in oesophageal atresia: morphological considerations by endoscopic and CT study. Eur J Cardiothorac Surg 2005;28:11–15.[Abstract/Free Full Text]
  11. Glick RD, La Quaglia MP. Lymphomas of the anterior mediastinum. Semin Pediatr Surg 1999;8:69–77.[Medline]
  12. Shamberger RC, Holzman RS, Griscom NT, Tarbell NJ, Weinstein HJ, Wohl ME. Prospective evaluation by computed tomography and pulmonary function tests of children with mediastinal masses. Surgery 1995;118:468–471.[CrossRef][Medline]
  13. Slinger P, Karsli C. Management of the patient with a large anterior mediastinal mass: recurring myths. Curr Opin Anaesthesiol 2007;20:1–3.[Medline]
  14. Schlesinger AE, Krishnamurthy R, Sena LM, et al. Incomplete double aortic arch with atresia of the distal left arch: distinctive imaging appearance. Am J Roentgenol (AJR) 2005;184:1634–1639.[Abstract/Free Full Text]
  15. Choo KS, Lee HD, Ban JE, et al. Evaluation of obstructive airway lesions in complex congenital heart disease using composite volume-rendered images from multislice CT. Pediatr Radiol 2006;36:219–223.[CrossRef][Medline]
  16. Swischuk LE. Cardiovascuar system: imaging of the newborn, infant and child. 5th ed. Philadelphia, Pa: Lippincott Williams &Wilkins, 2003; 303–317.
  17. Swischuk LE. Alimentary tract, imaging of the newborn, infant and child. 5th ed. Philadelphia, Pa: Lippincott Williams &Wilkins, 2003; 350–356.
  18. Berrocal T, Madrid C, Novo S, Gutierrez J, Arjonilla A, Gomez-Leon N. Congenital anomalies of the tracheobronchial tree, lung, and mediastinum: embryology, radiology, and pathology. Radiographics 2004;24:e17.[Abstract/Free Full Text]
  19. Kim HJ, Shin JH, Hong SJ, Park SJ, Lee SY, Song HY. Treatment of congenital tracheal stenosis with balloon-assisted posterior tracheal splitting and temporary placement of a covered retrievable metallic stent. J Vasc Interv Radiol 2005;16:287–289.[Medline]
  20. Legasto AC, Haller JO, Giusti RJ. Tracheal web. Pediatr Radiol 2004;34:256–258.[CrossRef][Medline]
  21. Miller BJ, Morrison MD. Congenital tracheal web: a case report. J Otolaryngol 1978;7:218–222.[Medline]
  22. Ghaye B, Szapiro D, Fanchamps JM, Dondelinger RF. Congenital bronchial abnormalities revisited. Radiographics 2001;21:105–119.[Abstract/Free Full Text]
  23. McGuinness G, Naidich DP, Garay SM, Davis AL, Boyd AD, Mizrachi HH. Accessory cardiac bronchus: CT features and clinical significance. Radiology 1993;189:562–566.
  24. Goo JM, Im J-G, Ahn JM, et al. Right paratracheal air cysts in the thoracic inlet: clinical and radiologic significance. Am J Roentgenol (AJR) 1999;173:65–70.[Abstract/Free Full Text]
  25. John SD, Swischuk LE. Stridor and upper airway obstruction in infants and children. Radiographics 1992;12:625–643.[Abstract]
  26. Hopkins A, Lahiri T, Salerno R, Heath B. Changing epidemiology of life-threatening upper airway infections: the reemergence of bacterial tracheitis. Pediatrics 2006; 118:1418–1421.[Abstract/Free Full Text]
  27. Stroud RH, Friedman NR. An update on inflammatory disorders of the pediatric airway: epiglottitis, croup, and tracheitis. Am J Otolaryngol 2001;22:268–275.[CrossRef][Medline]
  28. Graf J, Stein F. Tracheitis in pediatric patients. Semin Pediatr Infect Dis 2006;17:11–13.[CrossRef][Medline]
  29. Lee KS, Ernst A, Trentham DE, Lunn W, Feller-Kopman DJ, Boiselle PM. Relapsing polychondritis: prevalence of expiratory CT airway abnormalities. Radiology 2006;240:565–573.[Abstract/Free Full Text]
  30. Behar JV, Choi YW, Hartman TA, Allen NB, McAdams HP. Relapsing polychondritis affecting the lower respiratory tract. Am J Roentgenol (AJR) 2002;178:173–177.[Abstract/Free Full Text]
  31. Davitt SM, Hatrick A, Sabharwal T, Pearce A, Gleeson M, Adam A. Tracheobronchial stent insertions in the management of major airway obstruction in a patient with Hunter’s syndrome (type-II mucopolysaccharidosis). Eur Radiol 2002;12:458–462.[CrossRef][Medline]
  32. Choong CK, Sweet SC, Zoole JB. Bronchial airway anastomotic complications after pediatric lung transplantation: incidence, cause, management, and outcome. J Thorac Cardiovasc Surg 2006;131:198–203.[Abstract/Free Full Text]
  33. Friedman EM. Tracheobronchial foreign bodies. Otolaryngol Clin North Am 2000;33:179–185.[CrossRef][Medline]
  34. Kosucu P, Ahmetoglu A, Koramaz I, et al. Low-dose MDCT and virtual bronchoscopy in pediatric patients with foreign body aspiration. Am J Roentgenol (AJR) 2004;183:1771–1777.[Abstract/Free Full Text]
  35. Heyer CM, Bollmeier ME, Rossler L, et al. Evaluation of clinical, radiologic, and laboratory prebronchoscopy findings in children with suspected foreign body aspiration. J Pediatr Surg 2006;41:1882–1888.[CrossRef][Medline]
  36. Applegate KE, Dardinger JT, Lieber ML, et al. Spiral CT scanning technique in the detection of aspiration of LEGO foreign bodies. Pediatr Radiol 2001;31:836–840.[CrossRef][Medline]
  37. Bitar MA, Moukarbel RV, Zalzal GH. Management of congenital subglottic hemangioma: trends and success over the past 17 years. Otolaryngol Head Neck Surg 2005;132:226–231.[CrossRef][Medline]
  38. Sie KC, Tampakopoulou DA. Hemangiomas and vascular malformations of the airway. Otolaryngol Clin North Am 2000;33:209–220.[CrossRef][Medline]
  39. Somorai M, Goldstein NA, Alexis R, Giusti RJ. Managing isolated subglottic juvenile xanthogranuloma without tracheostomy: case report and review of literature. Pediatr Pulmonol 2007;42:181–185.[CrossRef][Medline]
  40. Kim TS, Han J, Kim GY, Lee KS, Kim H, Kim J. Pulmonary inflammatory pseudotumor (inflammatory myofibroblastic tumor): CT features with pathologic correlation. J Comput Assist Tomogr 2005;29:633–639.[CrossRef][Medline]
  41. Agrons GA, Rosado-de-Christenson ML, Kirejczyk WM, Conran RM, Stocker JT. Pulmonary inflammatory pseudotumor: radiologic features. Radiology 1998;206:511–518.[Abstract/Free Full Text]
  42. Curtis JM, Lacey D, Smyth R, Carty H. Endobronchial tumours in childhood. Eur J Radiol 1998;29:11–20.[CrossRef][Medline]
  43. Kothari NA, Kramer SS. Bronchial diseases and lung aeration in children. J Thorac Imaging 2001;16:207–223.[CrossRef][Medline]




This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Right arrow CME Test (opens in a new window)
Right arrow AVI Movie
Right arrow All Versions of this Article:
e29v1
28/3/e29    most recent
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Yedururi, S.
Right arrow Articles by Krishnamurthy, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Yedururi, S.
Right arrow Articles by Krishnamurthy, R.
Related Collections
Right arrow Magnetic Resonance Imaging
Right arrow Pediatric Radiology

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
RADIOGRAPHICS RADIOLOGY RSNA JOURNALS ONLINE