Airway involvement in pulmonary tuberculosis

Comparison of chest radiographs against minimum intensity projection reconstruction computed tomography scans for detection of airway stenosis in children with lymphobronchial tuberculosis

BACKGROUND

Ideally, suspected airway compression in symptomatic children with lymphobronchial tuberculosis (TB) would be diagnosed using modern computed tomography (CT) assisted by coronal minimum intensity projection (MinIP) reconstructions. However, in TB-endemic regions with limited resources, practitioners rely on conventional radiography for diagnosing TB and its complications. Furthermore, airway compression detected on conventional radiographs would upgrade a patient into the severe category according to the new World Health Organization guidelines, precluding the patient from shorter treatment protocols. The accuracy of conventional radiographs in the context of detecting airway compression in children with TB has not been specifically evaluated against an imaging gold standard.

OBJECTIVE

We aimed to compare frontal chest radiographs against thick-slab angled coronal CT MinIP in identifying airway stenosis at ten specific sites and to determine observer agreement between the modalities regarding the degree of stenosis.

MATERIALS AND METHODS

This retrospective cross-sectional study compared chest radiographs with standardized angled coronal CT MinIP in children with symptomatic lymphobronchial TB at ten predetermined airway locations. Chest radiographs were evaluated by one pediatric radiologist and CT MinIP reconstructions were independently interpreted by three readers. Sensitivity and specificity were calculated using CT MinIP as the gold standard. Stenosis was graded as 1 for mild (1-50%), 2 for moderate (51-75%), 3a for severe (76-99%), and 3b for total occlusion (100%). Agreement between the two modalities regarding severity of stenosis was calculated using the kappa coefficient for each affected site.

RESULTS

A total of 37 patients were included in the study. The median age of patients was 14.3 months (interquartile range 8.0-23.2). Three hundred and seventy individual bronchi (10 from each of the 37 patients) were evaluated for stenosis. Chest radiographs showed that 31 out of 37 (84%) patients had stenosis in at least one of ten evaluated sites, most commonly the left main bronchus and bronchus intermedius, and this was confirmed via CT MinIP. The gold standard (CT MinIP) demonstrated stenosis in at least one of ten sites in all 37 patients (100%). Left main bronchus stenosis was detected by chest radiography with a 92.9% sensitivity and 100% specificity. Sensitivity and specificity for bronchus intermedius stenosis were 80% and 75%, respectively. There was substantial agreement for grade of stenosis between chest radiographs and CT (kappa=0.67) for the left main bronchus and moderate agreement (kappa=0.58) for the bronchus intermedius. Severe stenosis was found in 78 bronchi on CT compared to 32 bronchi (Grade 3a: 9, Grade 3b: 23) on chest radiographs.

CONCLUSION

The diagnosis of pulmonary TB in children continues to rely heavily on imaging, and we have shown that in young children, chest radiographs had a high sensitivity and specificity for detecting airway stenosis at certain anatomical sites, when adequately visualized, resulting from tuberculous lymph node compression at left main bronchus and bronchus intermedius. For most sites, the interobserver agreement was poor. Stenosis of the left main bronchus and bronchus intermedius should be the focus of chest radiograph interpretation and can assist both diagnosis and classification of patients for treatment.

Interventional bronchoscopy in pediatric pulmonary tuberculosis

INTRODUCTION

Lymphobronchial tuberculosis (TB) is common in children with primary TB and enlarged lymph nodes can cause airway compression of the large airways. If not treated correctly, airway compression can result in persistent and permanent parenchymal pathology, as well as irreversible lung destruction. Bronchoscopy was originally used to collect diagnostic samples; however, its role has evolved, and it is now used as an interventional tool in the diagnosis and management of complicated airway disease. Endoscopic treatment guidelines for children with TB are scarce.

AREAS COVERED

The role of interventional bronchoscopy in the diagnosis and management of complicated pulmonary TB will be discussed. This review will provide practical insights into how and when to perform interventional procedures in children with complicated TB for both diagnostic and therapeutic purposes. This discussion incorporates current scientific evidence and refers to adult literature, as some of the interventions have only been done in adults but may have a role in children. Limitations and future perspectives will be examined.

EXPERT OPINION

Pediatric pulmonary TB lends itself to endoscopic interventions as it is a disease with a good outcome if treated correctly. However, interventions must be limited to safeguard the parenchyma and prevent permanent damage.

Comparison of single coronal thick-slab minimum intensity projection with flexible bronchoscopy for airway compression in children with lymphobronchial tuberculosis

AIM

To generate standardised coronal minimum intensity projection (MinIP) computed tomography (CT) reconstructions, and compare these with flexible bronchoscopy in children with lymphobronchial tuberculosis (LBTB).

MATERIALS AND METHODS

Standardised coronal MinIP reconstructions were performed from CT images in children with LBTB and the findings of three readers were compared with the reference standard, flexible bronchoscopy (FB), regarding airway narrowing. Intraluminal lesions, the site of the stenosis, and the degree of stenosis were also evaluated. The length of stenosis was evaluated by CT MinIP only.

RESULTS

Sixty-five children (38 males; 58.5% and 27 females; 41.5%), with ages ranging from 2.5 to 144 months were evaluated. Coronal CT MinIP demonstrated a sensitivity of 96% and specificity of 89% against FB. The most common site of stenosis was the bronchus intermedius (91%), followed by the left main bronchus (85%), the right upper lobe bronchus RUL (66%), and the trachea (60%).

CONCLUSION

Coronal CT MinIP reconstruction is useful in demonstrating airway stenosis in children with lymphobronchial TB, with high sensitivity and specificity. CT MinIP had additional advantages over FB in that it allowed objective measurement of the diameter of stenosis, measurement of the length of stenosis, and evaluation of post-stenotic segments of the airways and lung parenchymal abnormalities.

Complicated intrathoracic tuberculosis: Role of therapeutic interventional bronchoscopy

In recent years bronchoscopy equipment has been improved with smaller instruments and larger size working channels. This has ensured that bronchoscopy offers both therapeutic and interventional options. As the experience of paediatric interventional pulmonologists continues to grow, more interventions are being performed. There is a scarcity of published evidence in the field of interventional bronchoscopy in paediatrics. This is even more relevant for complicated pulmonary tuberculosis (PTB). Therapeutic interventional bronchoscopy procedures can be used in the management of complicated tuberculosis, including for endoscopic enucleations, closure of fistulas, dilatations of bronchial stenosis and severe haemoptysis. Endoscopic therapeutic procedures in children with complicated TB may prevent thoracotomy. If done carefully these interventional procedures have a low complication rate.

A proposed CT classification of progressive lung parenchymal injury complicating pediatric lymphobronchial tuberculosis: From reversible to irreversible lung injury

Lymphobronchial tuberculosis (LBTB) is tuberculous lymphadenopathy affecting the airways, which is particularly common in children with primary TB. Airway compression by lymphadenopathy causes downstream parenchymal pathology, which may ultimately result in irreversible lung destruction, if not treated timeously. Computed tomography (CT) is considered the "gold standard" for detecting mediastinal lymph nodes in children with TB. CT is also the best way of imaging the airways of children with LBTB. The CT findings of the parenchymal complications and associations of LBTB on CT have been described, but no severity classification was provided to aid management decisions. Identifying the parenchymal complications of LBTB and recognizing their severity has clinical relevance. Using prior publications on LBTB and post obstructive lung injury we have used an image bank of CT scans in children with pulmonary TB, presenting with airway symptoms, to create a CT severity staging of lung injury in LBTB. The staging focuses on distinguishing nonsalvageable destruction (nonenhancing or cavitated lung) from salvageable lung parenchymal disease (enhancing and noncavitated) to inform the management decisions, which range from bronchoscopic airway clearance to surgical decompression of the compressing nodes.

Diagnosis and management of community-acquired pneumonia in children: South African Thoracic Society guidelines

BACKGROUND

Pneumonia remains a major cause of morbidity and mortality amongst South African children. More comprehensive immunisation regimens, strengthening of HIV programmes, improvement in socioeconomic conditions and new preventive strategies have impacted on the epidemiology of pneumonia. Furthermore, sensitive diagnostic tests and better sampling methods in young children improve aetiological diagnosis.

OBJECTIVES

To produce revised guidelines for pneumonia in South African children under 5 years of age.

METHODS

The Paediatric Assembly of the South African Thoracic Society and the National Institute for Communicable Diseases established seven expert subgroups to revise existing South African guidelines focusing on: (i) epidemiology; (ii) aetiology; (iii) diagnosis; (iv) antibiotic management and supportive therapy; (v) management in intensive care; (vi) prevention; and (vii) considerations in HIV-infected or HIVexposed, uninfected (HEU) children. Each subgroup reviewed the published evidence in their area; in the absence of evidence, expert opinion was accepted. Evidence was graded using the British Thoracic Society (BTS) grading system. Sections were synthesized into an overall guideline which underwent peer review and revision.

RECOMMENDATIONS

Recommendations include a diagnostic approach, investigations, management and preventive strategies. Specific recommendations for HIV infected and HEU children are provided.

VALIDATION

The guideline is based on available published evidence supplemented by the consensus opinion of SA paediatric experts. Recommendations are consistent with those in published international guidelines.

[Childhood tuberculosis]

Childhood TB is an indication of failing TB control in the community. It allows disease persistence in the population. Mortality and morbidity due to TB is high in children. Moreover, HIV co-infection and multidrug-resistant diseases are as frequent in children as in adults. Infection is more frequent in younger children. Disease risk after primary infection is greatest in infants younger than 2 years. In case of exposure, evidence of infection can be obtained using the tuberculin skin test (TST) or an interferon-gamma assay (IGRA). There is no evidence to support the use of IGRA over TST in young children. TB suspicion should be confirmed whenever possible, using new available tools, particularly in case of pulmonary and lymph node TB. Induced sputum, nasopharyngeal aspiration and fine needle aspiration biopsy provide a rapid and definitive diagnosis of mycobacterial infection in a large proportion of patients. Analysis of paediatric samples revealed higher sensitivity and specificity values of molecular techniques in comparison with the ones originated from adults. Children require higher drugs dosages than adults. Short courses of steroids are associated with TB treatment in case of respiratory distress, bronchoscopic desobstruction is proposed for severe airways involvement and antiretroviral therapy is mandatory in case of HIV infection. Post-exposure prophylaxis in children is a highly effective strategy to reduce the risk of TB disease. The optimal therapy for treatment of latent infection with a presumably multidrug-resistant Mycobacterium tuberculosis strain is currently not known.

Left main bronchus compression as a result of tuberculous lymphnode compression of the right-sided airways with right lung volume loss in children

RATIONALE

The superior mediastinal space is confined by the sterno-manubrium anteriorly and the vertebral column posterior. An abnormal relationship between the superior mediastinal structures may result in compression of the left main bronchus. In patients with right-sided pneumonectomy an exaggerated compensatory response may lead to stretching and compression of the remainder of the intra-thoracic airway. Lymphobronchial TB mimics pneumonectomy when it causes compression of the bronchus intermedius, between nodal lymphnode groups with resultant volume loss in the right lung and displacement of the mediastinum to the right. The left main bronchus may be at risk of compression due to rotation and displacement of the major vessels.

AIM

To report pediatric cases of right-sided lymphobronchial TB with volume loss, demonstrate the use of angle measurements to quantify mediastinal dynamics and support a pathogenetic theory for left main bronchus compression.

MATERIALS AND METHODS

CT scans in children with TB and right lung volume loss, were compared retrospectively with controls using angle measurements based on descriptions of the aorta-carinal syndrome and the post-pneumonectomy syndrome. The Mann-Whitney U-test was used to compare groups.

RESULTS

The "Pulmonary bifurcation angle" between the main pulmonary arteries reached statistical significance (P = 0.025). The "Pulmonary outflow tract rotation" angle (pulmonary trunk with the mid sagittal plane) approached statistical significance (P = 0.078). The left main bronchus ranged from complete obliteration in two patients to 0.7 cm. In 16 of 30 patients the size was reduced to less than 75% of expected.

CONCLUSION

In children with right lung volume loss from TB, the compression of the contralateral bronchus is due to narrowing of the pulmonary artery bifurcation angle as the main trunk rotates towards the midline. This is comparable to the post-pneumonectomy syndrome.

Overview of airway involvement in tuberculosis

Pulmonary tuberculosis is a ubiquitous infection and a re-emerging medical and socioeconomic problem resulting in increasing mortality and morbidity, especially in Asian countries. We aim to review the spectrum of imaging findings in airway involvement in tuberculosis through characteristic radiological images and to assess the role of computed tomography and image-guided interventions in the diagnosis and management of pulmonary tuberculosis.

Characteristic magnetic resonance imaging low T2 signal intensity of necrotic lung parenchyma in children with pulmonary tuberculosis

PURPOSE

To show that necrotic areas of the lung demonstrated on computed tomographic scanning in children with primary pulmonary tuberculosis (TB) may be of low signal intensity on T2.

MATERIALS AND METHODS

Review of magnetic resonance imaging scans (T1/T2/STIR/postgadolinium T1) in 6 children scanned because of low-density necrotic areas demonstrated on computed tomography scanning prior to bronchoscopic confirmation of pulmonary TB.

RESULTS

Abnormalities included airspace consolidation in 6 children (100%); central necrosis in 6 children (100%); nodules in 2 children (33.3%); and lymphadenopathy in 6 children (100%). Low T2 signal in the areas of necrosis was demonstrated in all 6 children (100%) and in an area of at least 2 × 2 cm; 1 child also showed an area of high signal (16.67%). Airspace consolidation demonstrated T2 high signal in all the children (100%). Both children with nodules demonstrated at least 1 nodule with a low signal in addition to the majority of high-signal nodules. Post gadolinium, the consolidation and all high-signal nodules demonstrated enhancement, whereas the areas of lung necrosis and low signal nodules showed no enhancement.

CONCLUSION

Lung parenchymal necrosis in primary pulmonary TB in children may be of low signal intensity on T2 and STIR magnetic resonance imaging. This may be distal to lymphobronchial obstruction and is probably due to the caseating necrosis.

CT features of lymphobronchial tuberculosis in children, including complications and associated abnormalities

BACKGROUND

Lymphobronchial tuberculosis (TB) is tuberculous lymphadenopathy involving the airways, which is particularly common in children.

OBJECTIVE

To describe CT findings of lymphobronchial TB in children, the parenchymal complications and associated abnormalities.

MATERIALS AND METHODS

CT scans of children with lymphobronchial TB were reviewed retrospectively. Lymphadenopathy, bronchial narrowing, parenchymal complications and associations were documented.

RESULTS

Infants comprised 51% of patients. The commonest site of lymphadenopathy was the subcarinal mediastinum (97% of patients). Bronchial compression was seen in all children (259 bronchi, of these 28% the bronchus intermedius) with severe or complete stenosis in 23% of affected bronchi. Parenchymal complications were present in 94% of patients, including consolidation (88%), breakdown (42%), air trapping (38%), expansile pneumonia (28%), collapse (17%) and bronchiectasis (9%), all predominantly on the right side (63%). Associated abnormalities included ovoid lesions, miliary nodules, pleural disease and intracavitary bodies.

CONCLUSION

Airway compression was more severe in infants and most commonly involved the bronchus intermedius. Numerous parenchymal complications were documented, all showing right-side predominance.

[Specific features of tuberculosis in childhood]

Primary infection with Mycobacterium tuberculosis usually occurs during childhood. The source of infection is most often an adult. The risk of infection in exposed children is modulated by various factors related to the infectiousness of the index case, exposure conditions, and the child himself. This review aims to describe the specific diagnostic and therapeutic features of latent TB infection and TB disease in childhood.

[Diagnosis of tuberculosis in pediatrics. Consensus document of the Spanish Society of Pediatric Infectology (SEIP) and the Spanish Society of Pediatric Pneumology (SENP)]

Tuberculosis is one of the most important health problems worldwide. There are an increased number of cases, including children, due to different reasons in developed countries. The most likely determining cause is immigration coming from high endemic areas. Measures to optimize early and appropriate diagnosis of the different forms of tuberculosis in children are a real priority. Two Societies of the Spanish Pediatric Association (Spanish Society of Pediatric Infectology and Spanish Society of Pediatric Pneumology) have agreed this Consensus Document in order to homogenize diagnostic criteria in pediatric patients.

Comparing three-dimensional volume-rendered CT images with fibreoptic tracheobronchoscopy in the evaluation of airway compression caused by tuberculous lymphadenopathy in children

BACKGROUND

Lymphobronchial tuberculosis (TB) causes airway compression in 38% of patients. The airway obstruction is conventionally assessed with fibreoptic tracheobronchoscopy (FTB). Multidetector-row spiral computed tomography (MDCT) with three-dimensional volume rendering (3-D VR) has significantly improved the imaging of the airways. No previous studies have assessed the accuracy of 3-D VR in determining the degree of airway compression in children due to TB lymphadenopathy.

OBJECTIVE

To compare 3-D VR CT to FTB for the assessment of airway compression due to TB lymphadenopathy in children.

MATERIALS AND METHODS

Included in the study were 26 children presenting with symptoms of airway compression caused by pulmonary TB. MDCT of the chest and FTB were performed in all patients. Retrospective 3-D VR reconstruction of the major airways was performed from the original CT raw data and used to evaluate the tracheobronchial tree for site and degree of airway compression and then compared to the FTB findings. FTB was used as the reference standard

RESULTS

By FTB 87 sites of airway compression were identified. Using the 3-D VR technique, 138 sites of airway compression were identified, of which 78 (90%) matched with the sites identified by FTB. The sensitivity and specificity of 3-D VR when compared with that of FTB was 92% and 85%, respectively. In four patients (15%), severe narrowing of the bronchus intermedius made FTB evaluation of the right middle and right lower lobe bronchi impossible. VR demonstrated significant distal obstruction in three of these four patients

CONCLUSION

3-D VR demonstrates a very good correlation with FTB in determining airway compression caused by TB lymphadenopathy in children. In combination with FTB, 3-D VR adds confidence to the bronchoscopy findings and complements FTB by adding additional information on the status of the airway distal to severe obstructions unreachable by FTB.