Etiology: Tracheal agenesis, which is a rare congenital anomaly of unknown etiology, is characterized by either partial or complete tracheal underdevelopment.4–6 This condition frequently is associated with maternal polyhydramnios, and a tracheoesophageal or bronchoesophageal fistula often is present concomitantly.^4–7 Three main types of tracheal agenesis exist. Type 1 consists of absent upper trachea and connection of the lower trachea to the esophagus; type 2 consists of a common bronchus connecting bilateral main bronchi to the esophagus; and type 3 consists of independent bilateral main bronchi arising from the esophagus (Fig. 52-1, A). Of these three types, type 2 is the most common. Affected patients typically present with severe respiratory distress and absence of an audible cry, and the airway cannot be intubated below the larynx immediately after birth.^4–7 The diagnosis of tracheal agenesis should be considered in any infant who demonstrates improved lung ventilation after placement of the endotracheal tube in the esophagus following an initial unsuccessful intubation attempt. Once tracheal agenesis is diagnosed, radiologists should look carefully for other congenital anomalies that frequently are associated with this condition, such as congenital heart disease, duodenal atresia, and radial ray anomalies.^4–7

Imaging: Chest radiographic imaging findings of tracheal agenesis often are nonspecific, such as absent or decreased lung volume. However, the diagnosis of tracheal agenesis should be considered when absence of the normal tracheal air lucency, abnormal carinal position, and placement of the endotracheal tube in the esophagus are seen on chest radiographs of infants with severe respiratory distress immediately after birth (Fig. 52-1, B and C). The diagnosis is confirmed by computed tomography (CT) and/or bronchoesophagoscopy.^4–8 These studies can show both the partial or complete tracheal underdevelopment and anomalous bronchi connected to the esophagus (Fig. 52-1, D).

Treatment and Follow-up: Because of difficulties related to both early diagnosis and treatment, tracheal agenesis usually is a fatal condition.4–7 The initial management of tracheal agenesis is aimed at early diagnosis at birth and immediate maintenance of airway patency, usually via the esophagus in the presence of a bronchoesophageal fistula. Although several surgical approaches have been proposed in the past, definitive treatment currently has not been established, and long-term survival of affected patients is rare. However, patients with short-segment tracheal agenesis may be amenable to direct tracheal anastomosis.^5,7

Etiology: Tracheal bronchus is a congenital bronchial branching anomaly in which an ectopic (more frequently) or supernumerary bronchial branch arises from the lateral tracheal wall just above the carina.9–15 This condition also is known as bronchus suis because it is a normal finding in pigs. The incidence of tracheal bronchus in the pediatric population is between 0.1% and 5%.¹⁶ Although tracheal bronchus most frequently occurs on the right side, it also can present on the left side or bilaterally. Most patients with tracheal bronchus are asymptomatic, and it is usually an incidental finding detected on imaging studies obtained for the workup of other medical conditions. However, patients with tracheal bronchus also may present with symptoms such as persistent or recurrent upper lobe pneumonia, atelectasis, or air trapping.¹¹ Additionally, tracheal bronchus may unexpectedly be discovered after intubation as a result of upper lobe atelectasis related to inadvertent occlusion of the ectopic upper lobe bronchial orifice by a low-lying endotracheal tube.¹⁴

Imaging: On chest radiographs, secondary imaging findings of tracheal bronchus such as upper lobe atelectasis or pneumonia can be detected, but the anomalous upper lobe bronchus cannot be reliably visualized. In the past, tracheal bronchus was evaluated with tracheobronchography. However, CT with two-dimensional (2D) and three-dimensional (3D) reconstructions is now the imaging technique of choice for evaluating anomalous tracheal bronchus and associated lung abnormalities17–19 (Fig. 52-2). Bronchoscopy can confirm the diagnosis of tracheal bronchus when necessary.

Treatment and Follow-up: Pediatric patients with incidentally detected tracheal bronchus generally do not require any treatment. However, symptomatic children with recurrent upper lobe infection due to tracheal bronchus may require surgical resection, especially if permanent lung damage has developed or they are considered at risk for the development of permanent lung damage.¹

Etiology: Esophageal bronchus or lung is a rare congenital anomaly.11,20 The term “esophageal bronchus” refers to the condition in which a lobar bronchus, typically the medial basal segment of the right lower lobe, arises directly from the esophagus. The term “esophageal lung” is used when the main bronchus arises directly from the esophagus. This condition most commonly presents in infants but may be diagnosed at any age. It is associated with a wide spectrum of clinical presentations ranging from asymptomatic to recurrent severe pulmonary infections or even death depending on the size and location of the anomaly. In general, symptomatic pediatric patients with esophageal bronchus or lung typically present with feeding difficulties and recurrent respiratory tract infections. Other associated congenital anomalies include congenital heart disease, duodenal atresia, duodenal stenosis, distal tracheoesophageal fistula, and esophageal atresia.

Imaging: On chest radiographs, affected patients typically present as a result of aspiration during feeding, with air space opacification in the medial lower lobe in the case of esophageal bronchus and air space opacification that involves the entire lung in the case of esophageal lung.1,11 An esophagogram can provide a definitive diagnosis by allowing visualization of a direct communication between a bronchus and the esophagus (Fig. 52-3). CT may be helpful for evaluating associated lung parenchymal abnormalities and guiding surgery.

Treatment and Follow-up: Surgical lobectomy or pneumonectomy is the current management of choice for symptomatic patients with esophageal bronchus or lung, respectively.²⁰

Etiology: Congenital tracheal stenosis is a rare condition characterized by intrinsic narrowing of the tracheal lumen, usually as a result of underlying complete cartilaginous rings.2,3,21,22 Such cartilaginous rings with an absent or deficient posterior membranous portion render the tracheal lumen smaller and less pliable. Affected patients present in the first year of life with expiratory stridor, wheezing, and respiratory distress.^2,3,21,22 Congenital tracheal stenosis traditionally is classified into three types, including (1) focal (50%), (2) generalized (30%), and (3) funnel shaped (20%).²³ Other congenital anomalies often associated with congenital tracheal stenosis are tracheoesophageal fistula, pulmonary agenesis or hypoplasia, pulmonary artery sling type 2, and bronchial stenosis.^2,3,11,24

Imaging: Although neck and chest radiographs or fluoroscopy may lead to the suspicion of congenital tracheal stenosis when a narrowed trachea is encountered in pediatric patients with respiratory symptoms, CT is the imaging modality of choice for diagnosis and characterizion.2,4,24 With CT, the diagnosis of congenital tracheal stenosis is based on the identification of decreased caliber of the trachea without evidence of tracheal wall thickening. The size of the subglottic region (which does not contain tracheal cartilage) can serve as an internal reference standard. The use of 2D/3D reconstructed CT imaging is particularly helpful for increasing detection of subtle stenoses, improving measurement of craniocaudal extent of disease, and enhancing evaluation of its anatomic relationship with other mediastinal structures for preoperative assessment (Fig. 52-4).^2,4,24 Virtual bronchoscopic images can confirm the diagnosis of complete rings by showing concentric rings extending along the posterior wall of the trachea.²⁵ This appearance contrasts with the normal appearance in which the C-shaped rings do not extend to the posterior membranous wall.²⁵ In addition, virtual bronchoscopy has the capability of evaluating the airways distal to high-grade trachea stenoses, beyond which a conventional bronchoscope cannot pass.^2,4,24,25 CT also may aid in the detection of other associated anomalies that often have an abnormal lung component.

Treatment and Follow-up: Treatment of congenital tracheal stenosis mainly depends on the following three factors: (1) degree, (2) location, and (3) extent of the tracheal narrowing. A short tracheal stenosis may be treated by end-to-end anastomosis, whereas a longer lesion may require a patch or autograft repair.²² Other available options for short-segment tracheal stenosis include stent placement or balloon dilatation, although these methods are used more commonly to treat acquired tracheal stenosis.

Etiology: Tracheobronchomegaly, also known as Mounier-Kuhn syndrome, is a rare disorder characterized by dilatation of the trachea and main bronchi.26–28 Although the exact etiology of this condition currently is unknown, a defect in the elastic and muscular tissues of the large airways is presumed to be a potential underlying cause. The increased compliance of the large airway walls as a result of the atrophy of longitudinal elastic fibers with thinning of the muscularis mucosa often results in the development of broad, diverticulum-like protrusions of redundant musculomembranous tissue between the cartilaginous rings. It may occur either as a familial condition or in association with a connective tissue disorder such as Ehlers-Danlos syndrome.²⁹ It typically occurs in pediatric patients who have received prolonged ventilatory support or who have a chronic pulmonary infection such as cystic fibrosis. Although the clinical manifestations of tracheobronchomegaly are nonspecific, affected patients may present with a harsh cough, copious purulent sputum, occasional hemoptysis, and progressive dyspnea.

Imaging: Chest radiographs alone may be adequate to detect the enlargement of trachea and bronchi in severe cases (Fig. 52-5), but CT is the imaging modality of choice for diagnosing tracheobronchomegaly, potential tracheal diverticulum, and associated lung abnormalities (Fig. 52-6).¹ Because of the increased incidence of tracheobronchomalacia (TBM) in patients with tracheobronchomegaly, a dynamic CT study consisting of both inspiratory and expiratory phase imaging may be beneficial for detecting concomitant TBM.

Treatment and Follow-up: Asymptomatic pediatric patients with tracheobronchomegaly require no specific treatment. For symptomatic patients, treatment usually is conservative, including chest physiotherapy for assistance with clearing of secretions and antibiotics for treatment of pulmonary infections.30,31 Unfortunately, the generalized nature of this disorder limits possible benefits from surgical management.

Etiology: Foreign body aspiration into the tracheobronchial airway is a frequent cause of acute respiratory distress in pediatric patients, especially those between 6 months and 3 years of age.1–3,32,33 Each year, aspirated foreign bodies are responsible for approximately 160 deaths in children aged 14 years or younger in the United States alone, along with substantial additional morbidity.^32,33 Although some pediatric patients may present with a clinical history of possible aspiration followed by cough, wheezing, respiratory distress, or decreased breath sounds, most affected pediatric patients present with a history that is either lacking or misleading.^1–3,32,33 Therefore a high clinical suspicion and thorough investigation are required for any infants and young children with respiratory symptoms suspicious for possible foreign body aspiration.

Only approximately 10% of aspirated foreign bodies within the tracheobronchial airway are radiopaque.³⁴ The remaining 90% of nonradiopaque foreign bodies are particularly difficult to diagnose early in pediatric patients. Nearly 70% of aspirated foreign bodies lodge in the bronchi, with the right side (52%) affected more frequently than the left side (18%).³² The remaining 30% of aspirated foreign bodies lodge in the trachea (13%) and less common locations (17%).³² In the early phase of foreign body aspiration, affected patients typically present with cough, wheezing, respiratory distress, or decreased breath sounds. During the late phase of missed foreign body aspiration, affected patients often present with episodic wheezing and/or recurrent pneumonias.

Imaging: Radiographic findings of foreign body aspiration depend on the size, location, duration, and nature of the aspirated foreign body (Fig. 52-7). Radiopaque foreign bodies usually are detected easily with radiographic studies, which should include frontal and lateral films encompassing the upper airway from the nasopharynx to the upper abdomen. When the foreign body is not radiopaque, careful inspection of the tracheobronchial airway with high-kilovoltage films or fluoroscopy may show a faintly visible opacity interrupting the air column within the large airways. If the foreign object is located in the trachea, the chest radiograph may be normal or may show bilateral hypoinflation or hyperinflation depending on the degree of obstruction. Many intratracheal foreign bodies escape detection without the use of CT.

Rather than lodging in the trachea, most foreign bodies lodge in the main bronchi. In approximately 20% of cases, the foreign body migrates into a segmental bronchial branch.³² The chest radiograph may show a variety of findings, the most common of which is a unilateral hyperlucent lung. If the bronchial obstruction becomes more complete, postobstructive atelectasis, pneumonia, or bronchiectasis may develop. A chest radiograph obtained at full inspiration can appear normal in approximately 20% to 30% of patients with bronchial foreign bodies; close inspection may show relatively increased volume on the normal side with a slight mediastinal shift toward the partially obstructed side. If a foreign body is suspected clinically, an expiratory chest radiograph always should be obtained, because it is critical for diagnosis. Lateral decubitus films may be diagnostic if satisfactory inspiration-expiration chest radiographs cannot be obtained. When air trapping is present in a dependent lung on the decubitus view, the affected lobe or segment tends to remain hyperlucent rather than deflating, as would normally occur (Fig. 52-8). Fluoroscopic examination of the chest also is valuable for detecting air trapping. It can show inspiratory mediastinal shift toward the affected side and restricted diaphragmatic excursion on the affected side.

The sensitivity and specificity of chest radiographs for foreign body detection were only 74% and 45%, respectively, in a series of 93 patients examined by Silva et al³⁵ and 68% and 67%, respectively, in a series of 83 patients examined by Svedstrom et al.³⁶ Because of this relatively poor accuracy, Silva and colleagues have suggested that chest radiographs should not be relied upon for diagnosis, but rather that all patients with suspected foreign body aspiration should undergo bronchoscopy.³⁵ This approach results in a false-negative bronchoscopy rate of at least 20% in most series, however.³⁵

CT is the most sensitive diagnostic imaging technique, but in general it should be reserved for patients for whom chest radiography is either normal or nonspecific. With use of CT, the diagnosis of a foreign body can be established with nearly 100% accuracy.² Either the foreign body is visualized or a focal pulmonary abnormality such as postobstructive air trapping, atelectasis, or consolidation is seen. If none of these findings is present, it is extremely unlikely that a foreign body is present. However, CT is less likely to visualize the foreign body directly if the lung is consolidated unless the foreign body is calcified or opaque.

Preliminary studies of low-dose multidetector computed tomography (MDCT) virtual bronchoscopy suggest that it may play a potential role in children with suspected foreign body aspiration by (1) identifying the precise location of a foreign body prior to bronchoscopy and (2) excluding a foreign body in children with a low level of suspicion and normal or nonspecific findings on chest radiography.36–39 Because CT is less expensive and less invasive than bronchoscopy, it may be a viable alternative for selected patients.

Treatment and Follow-up: Once an aspirated foreign body is diagnosed on imaging studies, bronchoscopy and removal of the aspirated foreign body should be performed. Although imaging findings may be nonspecific or normal, symptomatic pediatric patients with high clinical suspicion and a convincing history of possible foreign body aspiration require bronchoscopy for a complete assessment. CT after bronchoscopy also is valuable because it provides additional diagnostic information regarding the presence and pattern of bronchial obstruction in symptomatic children with suspected residual foreign body.³⁴

Etiology: Tuberculosis (TB) is caused by Mycobacterium tuberculosis. Although advances in diagnosis and treatment have been made in the past two decades, TB continues to be a major cause of morbidity and mortality, particularly in infants, elderly persons, and immunocompromised patients.40,41 In developed countries, TB most commonly is transmitted to infants and children by an adult family member infected with active TB. Although most pediatric patients who have primary TB are asymptomatic, some patients may present with nonspecific symptoms such as a mild cough, a low-grade fever, weight loss, fatigue, and malaise. Respiratory distress may be the primary symptom in pediatric patients with large airway involvement from TB infection. The diagnosis usually can be made by TB skin testing, whereas sputum and gastric aspirates are confirmatory in anergic patients.

Imaging: Large airway involvement of TB infection mainly results from either extrinsic compression of airways by enlarged mediastinal and/or hilar infectious lymph nodes or direct infection of the airway wall through peribronchial lymphatic pathways.1–3,40–43 Although chest radiographs may show mediastinal and/or hilar lymphadenopathy with resultant large airway narrowing, the location, degree, and extent can be better evaluated with CT with 2D/3D reconstructions (Fig. 52-9).^1–3 Direct tracheobronchial infection from TB eventually may result in irreversible large airway stricture/stenosis.^{1–3,40–43} Such narrowing of the large airway is best assessed with CT with 2D/3D reconstructions. Additionally, CT also can show lung abnormalities associated with TB infection such as “tree-in-bud” nodular opacities and airspace consolidation.

Treatment and Follow-up: Pediatric patients affected with TB currently are treated with 6 months of a combination of antibiotics containing rifampin along with isoniazid, pyrazinamide, and ethambutol for the first 2 months, followed by isoniazid alone for the following 4 months. Large airway narrowing due to extrinsic compression from the enlarged mediastinal lymph nodes often resolves after medical treatment, whereas irreversible stricture/stenosis from direct tracheobronchial TB infection may require surgical management, including primary end-to-end anastomosis after stricture resection.

Etiology: Histoplasmosis is caused by the dimorphic fungus Histoplasma capsulatum. Although H. capsulatum is found throughout the world, it is endemic in certain areas, including states bordering the Ohio River valley, the lower Mississippi River, and caves in southern and East Africa. Although acute histoplasmosis is attributed to airborne primary infection, chronic progressive histoplasmosis is the consequence of reactivation of a prior infection. Large airway involvement from histoplasmosis often results from fibrosing mediastinitis.44–46 Affected patients may present with respiratory or esophageal symptoms related to complete or partial obstruction of large airways and the esophagus.^45,46 The definitive diagnosis of histoplasmosis is made by finding the fungus in samples taken from sputum, blood, or infected organs. It also can be diagnosed by identifying antigens in blood or urine samples by enzyme-linked immunosorbent assay polymerase chain reaction protocol.

Imaging: On chest radiographs, typical imaging findings of pediatric patients with histoplasmosis infection include multiple, ill-defined pulmonary nodules (1 to 3 cm in diameter) and hilar and/or mediastinal lymphadenopathy, both of which often are calcified.⁴⁴ CT currently is the imaging modality of choice for evaluating large airway compromise, particularly related to underlying fibrosing mediastinitis.^1–3 These patients typically show heterogeneous and often calcified mediastinal soft tissue densities resulting in complete or partial obstruction of mediastinal structures such as the tracheobronchial airway, superior vena cava, and esophagus (Fig. 52-10).^1–3,45,46 CT also can demonstrate abnormal lung findings from histoplasmosis infection.

Treatment and Follow-up: In severe cases, antifungal medications such as itraconazole and amphotericin B are used to treat acute, chronic, and disseminated histoplasmosis infection. Unfortunately, no pharmacologic treatment has been shown to affect the outcome of fibrosing mediastinitis related to histoplasmosis infection. Large airway occlusion due to fibrosing mediastinitis is particularly difficult to treat because surgery often is ineffective and placement of metallic airway stents is avoided because of recurrent obstruction from ingrowth of granulation tissue.

Etiology: A carcinoid tumor is a neuroendocrine neoplasm that encompasses a spectrum of histology ranging from slow-growing, locally infiltrative lesions to a metastasizing neoplasm.47–52 Carcinoid tumors traditionally have been classified into two types based on typical or atypical histologic findings. Affected patients typically present with a cough, wheezing, and recurrent pneumonia as a result of airway obstruction. Because of the underlying hypervascularity of carcinoid tumors, hemoptysis may be the presenting symptom. The carcinoid syndrome rarely occurs in pediatric patients with a large airway carcinoid tumor. The diagnosis is confirmed by bronchoscopy and biopsy.

Imaging: Imaging findings of a carcinoid tumor within the large airway depend on the size and location of the tumor.47–52 Most tracheobronchial carcinoid tumors are intrabronchial (Fig. 52-11). Centrally located carcinoid tumors may mimic foreign bodies and may cause postobstructive air trapping, atelectasis, recurrent infection, abscess, or bronchiectasis.⁵¹ Peripherally located carcinoid tumors usually are not associated with bronchial obstruction and have the appearance of a pulmonary nodule.⁵¹ Chest radiographs may be normal in 10% of cases or may show either a well-defined hilar or perihilar opacity representing an underlying tumor or secondary signs such as focal air trapping or consolidation.^47–52 CT characteristically shows an enhancing spherical or ovoid mass with a well-defined lobulated contour.^51,52 Although calcification may not be clearly visible on chest radiographs, either punctate or diffuse calcifications may be detected in up to 30% of cases on CT.⁵² The tumor may recur locally after resection, but distant metastases are rare.

Treatment and Follow-up: The current treatment of choice for large airway carcinoid tumors is complete surgical resection with primary reanastomosis or sleeve resection. Prognosis is excellent.

Etiology: Acquired tracheobronchial stenosis in children usually is caused by previous instrumentation such as endotracheal intubation or use of a tracheostomy tube.1–3 Granulation tissue and fibrosis can develop at the stoma, at the tip of the tube, or at the site of the cuff. Scott and Kramer⁵³ reported tracheostomy-related complications in 26% of intubated children. The duration of intubation is a major factor in determining the incidence and severity of complications. Microscopic lesions occur after approximately 48 hours of intubation. Epithelial metaplasia is seen in children intubated for longer than 7 days, although occasionally granuloma may develop after very brief periods of intubation. Bronchial stenosis, like tracheal stenosis, usually is acquired and occurs at the site of surgical anastomosis in pediatric patients after lung transplantation.^1–3

Imaging: The diagnosis of tracheobronchial stenosis may be suspected on chest radiographs when large airway narrowing is observed. However, CT, which can measure cross-sectional areas of the large airways accurately, is the current choice for evaluating tracheobronchial stenosis, especially preoperatively.1–3 Such stenosis may be weblike or fusiform, or it may have an irregular shape (Fig. 52-12).^1–3,54 Newer techniques such as paired inspiratory and expiratory CT or real-time dynamic four-dimensional CT can help differentiate a fixed tracheobronchial stenosis from TBM.^54–59 In some patients, these conditions may coexist.

Treatment and Follow-up: A short tracheobronchial stenosis may be treated by balloon dilatation, stent placement, or end-to-end anastomosis after surgical resection of the stenotic segment. A longer stenosis may require a patch or autograft repair.⁵⁸

Etiology: Tracheobronchial injury is a potentially life-threatening condition that may be caused by either penetrating or blunt chest trauma.60–66 Although tracheobronchial injury is relatively rare with a reported incidence between 0.7% and 2.9%, it is associated with a substantial mortality of 30%.^60–71 Tracheobronchial injury typically occurs within 2.5 cm of the carina.^60–69 In the setting of trauma, abnormal endotracheal tube position, rib fractures (particularly involving the anterior ends of the first three ribs), and persistent pneumothoraces and/or pneumomediastinum despite the presence of a well-functioning chest tube and/or mediastinal tube should raise the possibility of underlying tracheobronchial injury.^70,71

Imaging: Radiographic imaging findings of a traumatic tracheobronchial injury depend on the location and degree of injury. In the setting of mild injury, a small amount of pneumothorax and/or pneumomediastinum may be the only findings. Such nonspecific and subtle radiographic findings often delay the accurate diagnosis of tracheobronchial injury, particularly in pediatric patients.60,61,66 Extensive pneumothorax and/or pneumomediastinum, often extending into subcutaneous tissues of the neck and chest wall, typically are seen with severe injuries such as a displaced laceration or transection.^60–71 When the collapsed lung is observed in a dependent position, hanging on the hilum only by its vascular attachments (the “fallen lung sign”), a complete transaction or rupture of the main stem bronchus should be considered.¹ MDCT with thin-section axial and 2D/3D reconstruction can provide accurate diagnosis and preoperative guidance in these patients (Fig. 52-13).^1,68,70,71

Treatment and Follow-up: Individualized surgical repairs depend on the location and severity of injury and are performed via primary anastomosis or reimplantation.

Etiology: TBM is attributed to an abnormal weakness of the underlying airway walls and/or supporting cartilage.57,58,72 Despite increasing recognition of this condition in recent years, diagnosing TBM continues to be challenging mainly because clinical symptoms of affected patients are nonspecific and overlap with those of other chronic respiratory disorders.^57,58,72 TBM can be divided into two types: primary and secondary.^58,72 Primary TBM often is seen in premature infants or children with a variety of syndromes and in persons with systemic disease affecting cartilage, such as Larsen syndrome and relapsing polychondritis.^58,72 Secondary TBM is seen in infants or children with tracheoesophageal fistula, extrinsic pressure by vessels, and mediastinal masses.^58,72 It also may arise as a result of tracheal injury, most commonly intubation. Affected patients typically present with expiratory stridor and a cough that often is described as barking or brassy. Undiagnosed TBM may result in chronic tracheobronchial and lung infections.

Imaging: Chest radiographs and airway fluoroscopy have been used to evaluate TBM in pediatric patients in the past.¹ Fluoroscopy may show an exaggerated decrease (>50%) in the caliber of the trachea during expiration in patients with tracheomalacia^1,2 (Fig. 52-14); however, evaluation of the bronchi is markedly limited with this technique. MDCT has become the imaging modality of choice for a complete assessment of TBM and underlying causes in pediatric populations.^55–59 MDCT provides noninvasive evaluation of TBM with diagnostic accuracy that is similar to the historical reference standard of bronchoscopy, and 2D and 3D evaluation with MDCT in particular has become an important preoperative assessment of TBM because it offers information regarding the precise location, accurate degree and extent, and underlying predisposing conditions of TBM.^57,58,72 For the diagnosis of TBM with MDCT in children, tracheobronchial collapse >50% currently is used (Fig. 52-15).^57,58 The very large detector array CT scanners that have become available recently allow real-time evaluation of large airway collapsibility even in nonsedated infants and young children, which is a promising technique.^1,2

Treatment and Follow-up: Conservative therapies such as treatment of underlying respiratory infections, humidified oxygen therapy, and pulmonary physiotherapy are the mainstay of management in pediatric patients with a mild to moderate degree of TBM.72–74 However, pediatric patients with severe and progressively worsening TBM may require more aggressive treatment including tracheostomy placement, stent placement, and surgical intervention such as a tracheoplasty.^75–86