MDCT of Tracheobronchial Narrowing in Pediatric Patients

Pediatric large airway imaging: evolution and revolution

Infants and children often present with respiratory symptoms referable to the airway. For these pediatric patients, airway imaging is frequently performed to evaluate for underlying disorders of the large airway. Various imaging modalities have been used to evaluate the pediatric large airway, and pediatric airway imaging techniques have continued to evolve. Therefore, clear understanding of the status and new advances in pediatric large airway imaging is essential for practicing radiologists to make timely and accurate diagnoses, which can lead to optimal pediatric patient management.

Lung and large airway imaging: magnetic resonance imaging versus computed tomography

Disorders of the respiratory system are common in children and imaging plays an important role for initial diagnosis and follow-up evaluation. Radiographs are typically the first-line imaging test for respiratory symptoms in children and, when advanced imaging is required, CT has been the most frequently used imaging modality. However, because of increasing concern about potentially harmful effects of ionizing radiation on children, there has been a shift toward MRI in pediatric imaging. Although MRI of chest in children presents many technical challenges, recent advances in MRI technology are overcoming many of these issues, and MRI is now being used for evaluating the lung and large airway in children at centers with expertise in pediatric chest MRI. In this article we review the state of pediatric lung and large airway imaging, with an emphasis on cross-sectional modalities and the roles of MRI versus CT.

Infantile intrathoracic large airway obstruction in a setting with a high prevalence of tuberculosis/HIV

Background There has been no detailed analysis of the cause of intrathoracic large airway obstruction in infants in a resource-limited environment with a high prevalence of pulmonary tuberculosis (PTB) and human immunodeficiency virus (HIV). Aim To define the aetiology and severity of intrathoracic large airway obstruction in infants in a tertiary South African hospital with a high prevalence of PTB and HIV. Methods A retrospective study of infants was conducted with computerised tomography (CT) evidence of intrathoracic large airway obstruction from 1 January 2011 to 31 May 2014. CT scans were evaluated for the cause, site and severity of airway narrowing, with severity stratified as 'mild' (<50%), 'moderate' (51-75%) or 'severe' (>75%). Results Forty-four patients (28 males, 64%; median age 145 days, range 5-331), and 79 sites of attenuation were included. Vascular (22/44, 50%) and nodal (18/44, 41%) compressions accounted for over 90% of cases. Thirty-five patients (79.5%) had at least one site of moderate/severe attenuation, and 26 (59%) had multiple such sites. Adenopathy was the commonest cause of moderate/severe compression (18/35, 51%). All cases of nodal compression were of tuberculous origin. HIV-serology was recorded in 32 patients (73%), one of whom, with vascular compression, was HIV-infected. Half of the patients (11/22, 50%) with vascular compression had congenital abnormalities, most commonly cardiac anomalies (7/22, 32%). There were no synchronous vascular and nodal compressions. Conclusion Infantile intrathoracic large airway obstruction where there is a high prevalence of PTB and HIV is characterised by its extrinsic aetiology, severity and multicentricity, with more than half of all moderate/severe obstructions being caused by tuberculous adenopathy.

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

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

Tracheobronchomalacia in pediatric patients with esophageal atresia: comparison of diagnostic laryngoscopy/bronchoscopy and dynamic airway multidetector computed tomography

PURPOSE

Diagnostic laryngoscopy and bronchoscopy (DLB) has been the traditional preoperative diagnostic modality for evaluating presence and severity of tracheobronchomalacia (TBM), and requires anesthesia. Alternatively, multidetector computed tomography (MDCT) is potentially a noninvasive modality that provides high-resolution, 3-dimensional (3D) imaging of the thorax providing preoperative guidance for pediatric surgeons. This study compares MDCT with intraoperative DLB in the assessment of TBM in symptomatic pediatric patients with esophageal atresia (EA).

METHODS

Following IRB approval all pediatric patients (≤18 years) who had EA and who underwent an MDCT study as a preoperative evaluation of TBM prior to aortopexy were retrospectively reviewed. Patients with incomplete reports on intraoperative DLB or MDCT studies were excluded. Two pediatric radiologists independently evaluated all MDCT studies in a blinded fashion. On both DLB and MDCT studies, TBM was scored as present or absent in five anatomic segments: upper, middle, and lower trachea, as well as right and left main stem bronchi. Operative reports including DLB findings were reviewed and compared to findings from MDCT study using the chance corrected kappa (κ) coefficient. Diagnostic accuracy of dynamic MDCT for detecting TBM was determined by sensitivity and specificity, and interobserver agreement between two radiology reviewers was measured by the kappa statistic.

RESULTS

The final study population included 18 patients (8 males and 10 females) with ages ranging from 1month to 11years (median: 7 months). Their presenting clinical symptoms included apneic spells (n=15, 83%) and failure to extubate (n=3, 17%). The overall diagnostic accuracy of dynamic airway MDCT compared to DLB was 91% (82/90 possible segments for TBM) with excellent overall agreement across all 5 anatomic segments (κ=0.82, p<0.001). The agreements for upper, mid, lower trachea, and right and left trachea were 89% (κ=0.73, p<0.001), 94% (κ=0.85, p<0.001), 89% (κ=0.76, p<0.001), 94% (κ=0.82, p<0.001), and 89% (κ=0.61, p=0.005); respectively. Interobserver agreement between two radiologists was excellent (κ=0.98, 95% confidence interval: 0.94-1.00, p<0.001) with only 1 disagreement between two radiologists that was found for the left main bronchus. Fifteen (83.3%) of the patients clinically improved after the aortopexy.

CONCLUSION

MDCT with 3D imaging is a highly accurate and reliable preoperative noninvasive imaging modality for evaluating TBM in pediatric patients with EA providing anatomic information consistent with and complimentary to bronchoscopy.

Tracheobronchomalacia in infants: the use of non-breath held 3D CT bronchoscopy

OBJECTIVE

To evaluate the use of a non-breath held 3D-CT-bronchoscopy in detecting tracheobronchomalacia in infants.

METHODS

The study was based on 17 infants who received both bronchoscopy and 3D-CT-bronchoscopy within 1 week at our institution. 3D-CT-bronchoscopy consisted of an axial-enhanced-chest-scan and a 3D-volume-external rendering (VR) image of the airways and was scanned with a consciously sedated non-breath held protocol, using a 64-channel-multidetecter-CT scanner. VR images were classified by two radiologists as normal, luminal narrowing or complete obliteration. All patients were confirmed with bronchoscopy and the sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) was calculated.

RESULTS

Ten (M:F¼7:3, mean 1 month) out of 17 infants were confirmed of tracheobronchomalacia. The sensitivity was <75% in detecting laryngomalacia, tracheomalacia and bronchomalacia. However, the specificity and NPV were higher than 75% for laryngomalacia, tracheomalacia and bronchomalacia and the PPV was 100% in laryngomalacia and tracheomalacia. False-positive cases included secretion plugging, extrinsic compression and foreign body, which were distinguishable in axial scans. The effective radiation dose was 0.73_0.49mSv.

CONCLUSION

A volume rendering image of the airways can be used to evaluate tracheobronchomalacia and stenosis in infants. Although, non-breath held MDCT is not recommended for screening airway lesions, narrowing of the larynx, and trachea and patency of the bronchus are reliable findings.

Primary lung and large airway neoplasms in children: current imaging evaluation with multidetector computed tomography

Multidetector computed tomography (MDCT) offers an important noninvasive imaging modality for confirmation and further characterization of primary lung and large airway neoplasms encountered in pediatric patients. Children represent a unique challenge in imaging, not only because of unique patient factors (eg, inability to follow instructions, motion, need for sedation) but because of the technical factors that must be optimized to reduce radiation dose. This article reviews an MDCT imaging algorithm, up-to-date imaging techniques, and clinical applications of MDCT for evaluating benign and malignant primary neoplasms of lung and large airway in infants and children.

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

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

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

OBJECTIVE

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

SUBJECTS AND METHODS

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

RESULTS

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

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

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

Paediatric multi-detector row chest CT: what you really need to know

Background

The emergence of multi-detector row CT (MDCT) has established and extended the role of CT especially in paediatric chest imaging. This has altered the way in which data is acquired and is perceived as the 'gold standard' in the detection of certain chest pathologies. The range of available post-processing tools provide alternative ways in which CT images can be manipulated for review and interpretation in order to enhance diagnostic accuracy.

Methodology

Paediatric imaging technique/protocol together with radiation dose reduction is discussed in detail. The use of different post-processing tools to best demonstrate the wide range of important congenital anomalies and thoracic pathologies is outlined and presented pictorially.

Conclusion

MDCT with its isotropic resolution and fast imaging acquisition times reduces the need for invasive diagnostic investigations. However, users must be vigilant in their imaging techniques to minimise radiation burden, whilst maintaining good image quality.

Main Messages

• CT examinations should be clinically justified by the referring clinician and radiologist.

• MDCT is invaluable for evaluating the central airway, mediastinal structures and lung parenchyma.

• MDCT is more sensitive than plain radiographs in detection of structural changes within the lungs.

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

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

Update on multidetector computed tomography imaging of the airways

Recent advances in multidetector computed tomography (MDCT) technology have transformed the imaging evaluation of the trachea and bronchi. Multiplanar 2-dimensional and 3-dimensional volume reconstruction techniques, including external rendering and virtual bronchoscopy, can be generated in mere minutes, thereby complementing conventional axial CT imaging in the depiction of various central airway disease processes including airway stenoses, central airway neoplasms, and congenital airway disorders. Paired inspiratory and dynamic expiratory MDCT imaging, along with newer cine CT imaging methods, have enhanced the assessment of tracheobronchomalacia in both adults and the pediatric population. In addition, MDCT imaging plays an essential complementary role to conventional bronchoscopy, facilitating planning and guidance of bronchoscopic interventions, and providing a noninvasive method for postprocedural surveillance.

Modern imaging of the tracheo-bronchial tree

Recent state-of-the-art computed tomography and improved three-dimensional (3-D) postprocessing techniques have revolutionized the capability of visualizing airway pathology, offering physicians an advanced view of pathology and allowing for appropriate management planning. This article is a comprehensive review of trachea and main bronchi imaging, with emphasis on the dynamic airway anatomy, and a discussion of a wide variety of diseases including, but not limited to, congenital large airway abnormalities, tracheobronchial stenoses, benign and malignant neoplasms and tracheobronchomalacia. The importance of multiplanar reconstruction, 3-D reconstruction and incorporation of dynamic imaging for non-invasive evaluation of the large airways is stressed.

Minimally invasive innominate artery transection for tracheomalacia using 3-dimensional multidetector-row computed tomographic angiography: report of a case

We successfully performed transection of the innominate artery in a patient with a neuromuscular disorder through minimally invasive access after confirming the anatomical relationships of the vessel using 3-dimensional multidetector-row computed tomographic angiography. A 16-year-old girl with spinal muscular atrophy type 1 had been on long-term mechanical ventilation with a tracheostomy. She had scoliosis and tracheomalacia. Bronchoscopy showed a flattened and narrow lower trachea and an anterior pulsatile compression by the innominate artery. She underwent transection of the innominate artery to prevent tracheoinnominate artery fistula formation. Based on preoperative 3-dimensional multidetector-row computed tomographic angiography images, the innominate artery was transected through a small transverse curvilinear skin incision just below the suprasternal notch and an oblique partial manubriotomy from the suprasternal notch to the first left intercostal space.

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

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

Focal stenosis in right upper lobe bronchus in a recurrently wheezing child sequentially studied by multidetector-row spiral computed tomography and scintigraphy

Lower respiratory tract infections associated with wheezing are not uncommon in infants and young children. Among the wheezing-associated disorders, allergic etiologies are more commonly encountered than anatomic anomalies. We present a 3-year-old girl with a sudden attack of asthmatic symptoms including dyspnea, cyanosis and diffuse wheezing Based on a history of choking, and atelectasis in the right upper lobe detected by chest films, flexible tracheobronchoscopy was arranged and incidentally detected a stenotic orifice in the right upper lobe bronchus. Multidetector-row spiral computed tomography and pulmonary scintigraphy subsequently also disclosed the focal stenosis. She suffered from recurrent wheezing, pneumonia and lung atelectasis during 1 year of follow-up. We emphasize the diagnosis, clinical course and management of focal stenosis in the right upper lobe bronchus.

Tracheobronchomalacia in infants and children: multidetector CT evaluation

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

Complete tracheal duplication in an adult with thoracic aortic coarctation

Partial and complete duplication of the trachea have previously been reported as rare causes of respiratory distress in children. We report a case of complete tracheal duplication detected incidentally in an adult during a computed tomography angiogram of the heart performed as part of an evaluation for coarctation of the aorta.

Multidetector CT evaluation of congenital lung anomalies

Congenital lung anomalies vary widely in their clinical manifestation and imaging appearance. Although radiographs play a role in the incidental detection and initial imaging evaluation in patients with clinical suspicion of congenital lung anomalies, cross-sectional imaging such as computer tomography (CT) is frequently required for confirmation of diagnosis, further characterization, and preoperative evaluation in the case of surgical lesions. Recently, with the development and widespread availability of multidetector CT scanners, CT has assumed a greater role in the noninvasive evaluation of congenital lung anomalies. The combination of fast speed, high spatial resolution, and enhanced quality of multiplanar reformation and three-dimensional reconstructions makes multidetector CT an ideal noninvasive method for evaluating congenital lung anomalies. In this article, the authors review the multidetector CT technique for evaluation of congenital lung anomalies. Important clinical aspects, characteristic imaging features, and key points that allow differentiation among various anomalies are highlighted for a variety of common and uncommon conditions.

MDCT assessment of tracheomalacia in symptomatic infants with mediastinal aortic vascular anomalies: preliminary technical experience

BACKGROUND

Mediastinal aortic vascular anomalies are relatively common causes of extrinsic central airway narrowing in infants with respiratory symptoms. Surgical correction of mediastinal aortic vascular anomalies alone might not adequately treat airway symptoms if extrinsic narrowing is accompanied by intrinsic tracheomalacia (TM), a condition that escapes detection on routine end-inspiratory imaging. Paired inspiratory-expiratory multidetector CT (MDCT) has the potential to facilitate early diagnosis and timely management of TM in symptomatic infants with mediastinal aortic vascular anomalies.

OBJECTIVE

To assess the technical feasibility of paired inspiratory-expiratory MDCT for evaluating TM among symptomatic infants with mediastinal aortic vascular anomalies.

MATERIALS AND METHODS

The study group consisted of five consecutive symptomatic infants (four male, one female; mean age 4.1 months, age range 2 weeks to 6 months) with mediastinal aortic vascular anomalies who were referred for paired inspiratory-expiratory MDCT during a 22-month period. CT angiography was concurrently performed during the end-inspiration phase of the study. Two pediatric radiologists in consensus reviewed all CT images in a randomized and blinded fashion. The end-inspiration and end-expiration CT images were reviewed for the presence and severity of tracheal narrowing. TM was defined as > or =50% reduction in tracheal cross-sectional luminal area between end-inspiration and end-expiration. The presence of TM was compared to the bronchoscopy results when available (n = 4).

RESULTS

Paired inspiratory-expiratory MDCT was technically successful in all five patients. Mediastinal aortic vascular anomalies included a right aortic arch with an aberrant left subclavian artery (n = 2), innominate artery compression (n = 2), and a left aortic arch with an aberrant right subclavian artery (n = 1). Three (60%) of the five patients demonstrated focal TM at the level of mediastinal aortic vascular anomalies. The CT results were concordant with the results of bronchoscopy in all patients who underwent bronchoscopy (n = 4).

CONCLUSION

Paired inspiratory-expiratory MDCT is technically feasible for evaluating TM in symptomatic infants with mediastinal aortic vascular anomalies and has the potential to facilitate prompt diagnosis and treatment.