Dynamic and quantitative assessment of tracheomalacia by electron beam tomography: correlation with clinical symptoms and bronchoscopy

[Interventionnal bronchoscopy for the treatment of tracheobronchomalacia]

Tracheobronchomalacia is usually characterized by more than 50% expiratory narrowing in diameter of the trachea and the bronchi. The expiratory collapse includes two entities: (1) the TBM related to the weakness of the cartilaginous rings, and (2) the Excessive Dynamic Airway Collapse (EDAC) due to the excessive bulging of the posterior membrane. Patients have nonspecific respiratory symptoms like dyspnea and cough. Diagnosis is confirmed by dynamic tests: flexible bronchoscopy and/or computed tomographic scan of the chest. There are different forms of tracheobronchomalacia in adults: primary (genetic, idiopathic) or secondary to trauma, tracheotomy, intubation, surgery, transplantation, emphysema, infection, inflammation, chronic bronchitis, extrinsic compression; or undiagnosed in childhood vascular rings. Some management algorithms have been proposed, but no specific recommendation was established. Only symptomatic patients should be treated. Medical treatments and noninvasive positive pressure ventilation should be the first line therapy, after evaluation of various quality measures (functional status, performance status, dyspnea and quality of life scores). If symptoms persist, therapeutic bronchoscopy permits: (1) patient's selection by stent trial to determine whether patient benefit for surgical airway stabilization; (2) malacic airways stenting in patients who are not surgical candidates, improving QOL despite a high complication rate; (3) the management of stent-related complication (obstruction, plugging, migration granuloma); (4) alternative therapeutics like thermo-ablative solution. Lasty, the development of new types of stents would reduce the complication rates. These different options remained discussed.

Imaging Evaluation of Airway Complications After Lung Transplant

Airway complications (ACs) after lung transplant remain a challenge and include bronchial dehiscence, bronchial stenosis, tracheobronchomalacia, infections, and bronchial fistulas. The spectrum of complications may coexist along a continuum and can be classified as early (<1 month after transplant) or late (>1 month), and anastomotic or nonanastomotic. Bronchiolitis obliterans is the most common form of chronic lung allograft rejection. Airway compromise is seen in rare instances of lung torsion, and imaging may provide helpful diagnostic clues. Computed tomography (CT) and bronchoscopy play major roles in the diagnosis and treatment of ACs after lung transplant. Chest CT with advanced postprocessing techniques is a valuable tool in evaluating for airways complications, for initial bronchoscopic treatment planning and subsequent posttreatment assessment. Various bronchoscopic treatment options may be explored to maintain airway patency. The goal of this article is to review imaging findings of ACs after lung transplantation, with emphasis on chest CT and bronchoscopic correlation.

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.

Tracheobronchomalacia in children: review of diagnosis and definition

Tracheobronchomalacia is characterised by excessive airway collapsibility due to weakness of airway walls and supporting cartilage. The standard definition requires reduction in cross-sectional area of at least 50% on expiration. However, there is a paucity of information regarding the normal range of central airway collapse among children of varying ages, ethnicities and genders, with and without coexisting pulmonary disease. Consequently, the threshold for pathological collapse is considered somewhat arbitrary. Available methods for assessing the airway dynamically--bronchoscopy, radiography, cine fluoroscopy, bronchography, CT and MR--have issues with reliability, the need for intubation, radiation dose and contrast administration. In addition, there are varying means of eliciting the diagnosis. Forced expiratory manoeuvres have been employed but can exaggerate normal physiological changes. Furthermore, radiographic evidence of tracheal compression does not necessarily translate into physiological or functional significance. Given that the criteria used to make the diagnosis of tracheobronchomalacia are poorly validated, further studies with larger patient samples are required to define the threshold for pathological airway collapse.

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.

Airway malacia in chronic obstructive pulmonary disease: prevalence, morphology and relationship with emphysema, bronchiectasis and bronchial wall thickening

The aim of this study was to determine the prevalence of airway malacia and its relationship with ancillary morphologic features in patients with chronic obstructive pulmonary disease (COPD). A retrospective review was performed of a consecutive series of patients with COPD who were imaged with inspiratory and dynamic expiratory multidetector computed tomography (MDCT). Airway malacia was defined as > or =50% expiratory reduction of the airway lumen. Both distribution and morphology of airway malacia were assessed. The extent of emphysema, extent of bronchiectasis and severity of bronchial wall thickness were quantified. The final study cohort was comprised of 71 patients. Airway malacia was seen in 38 of 71 patients (53%), and such proportion was roughly maintained in each stage of COPD severity. Almost all tracheomalacia cases (23/25, 92%) were characterised by an expiratory anterior bowing of the posterior membranous wall. Both emphysema and bronchiectasis extent did not differ between patients with and without airway malacia (p > 0.05). Bronchial wall thickness severity was significantly higher in patients with airway malacia and correlated with the degree of maximal bronchial collapse (p < 0.05). In conclusion, we demonstrated a strong association between airway malacia and COPD, disclosing a significant relationship with bronchial wall thickening.

Multi-detector CT evaluation in patients suspected of tracheobronchomalacia: Comparison of end-expiratory with dynamic expiratory volumetric acquisitions

PURPOSE

The aim of this study was to compare dynamic expiratory imaging and end-expiratory imaging using multi-detector CT (MDCT) of the central airways in patients suspected of tracheobronchomalacia (TBM).

METHODS

This study had local ethical committee approval. Seventy patients suspected of TBM were prospectively included. All patients underwent evaluation of central airways by three different low-dose MDCT acquisitions: end inspiration, end expiration, and dynamic expiration. Degree of airway collapse was measured by calculating the percentage change in the area and diameter of the airways between inspiratory and the two expiratory techniques at three levels of the trachea and in the sagittal diameter of the right and left main bronchi. Three threshold levels of percentage reduction in diameter or area (30%, 50%, and 70%) for defining TBM were evaluated.

RESULTS

In the entire population, the mean percentage of airway collapse was significantly greater with dynamic expiratory imaging than with the end-expiratory imaging at three different levels: lower thoracic trachea (26% vs. 16.6%, p<0.009), right (25.2% vs. 14%, p<0.01) and left main (24.7% vs. 13.3%, p<0.01) bronchus. Whatever the threshold value for defining TBM, dynamic expiratory imaging always resulted in diagnosing TBM in more patients than end-expiratory imaging.

CONCLUSIONS

Dynamic expiratory imaging shows a significantly greater degree and a significantly greater extent of airway collapse than standard end-expiratory imaging in patients suspected of TBM. Further evaluation of the clinical relevance of such findings is warranted.

MDCT evaluation of central airway and vascular complications of lung transplantation

OBJECTIVE

The purpose of this article is to illustrate the spectrum of central airway and vascular complications in lung transplantation using MDCT, with an emphasis on the usefulness of advanced postprocessing techniques.

CONCLUSION

MDCT is an invaluable tool in the diagnosis, evaluation, and posttreatment assessment of central airway and vascular complications in lung transplant recipients. Advanced postprocessing techniques provide complementary information that is visually accessible and anatomically meaningful for the clinician.

Synchronous airway lesions in laryngomalacia

OBJECTIVE

Laryngomalacia is the most common cause of congenital stridor. Laryngomalacia may be associated with other structural and functional airway lesions. While previous studies suggested a 10-45% rate of synchronous airway lesions (SALs), the exact rate and it's clinical significance is unknown. The purpose of this study was to determine the prevalence of SALs below the glottic level in congenital laryngomalacia, and to investigate possible relations with other clinical findings.

METHODS

A cohort of 228 infants with congenital stridor who underwent fiberoptic flexible bronchoscopy (FFB) was analyzed. Data was collected from the hospital records. All procedures were reevaluated from the video recordings.

RESULTS

SALs below the vocal cords were observed in 7.5% of the case (17/228). The most common SAL was tracheal bronchus followed by tracheomalacia and stenosis of the left main bronchus. No correlation was found between the presence of a SAL below the vocal cords and any other medical condition except for neurodevelopmental disorders. Except for one patient, all cases with SAL did not have any clinical symptoms or signs that would have suggested an accompanying airway lesion.

CONCLUSIONS

The rate of SALs in infants with congenital stridor due to laryngomalacia is low and most of the additional lesions are benign. The yield of discovering clinically significant SALs below the glottic level is low and the routine search for a synchronous lesion below the vocal cords should be questioned. Except for underlying neurodevelopmental problems, no clear risk factors for the existence of SALs were identified.

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.

Description of a multidimensional classification system for patients with expiratory central airway collapse

BACKGROUND AND OBJECTIVE

Patients with expiratory central airway collapse present with various symptoms, aetiologies, morphologies, extent and severity of airway collapse. The aim of this study was to delineate a multidimensional classification system and common language for evaluating patients with expiratory central airway collapse.

METHODS

The classification system was based on the morphology and origin of the airway abnormality as well as stratification parameters such as functional status, extent and severity of airway collapse. Patients with expiratory central airway collapse who underwent clinical and bronchoscopic examination before and after treatment were identified from a bronchoscopy database. The classification was applied to the study patients before and after treatment to assess the utility of this stratification approach.

RESULTS

Eighteen patients were studied. Four had excessive dynamic airway collapse and 14 had tracheobronchomalacia. Post-treatment, functional status improved by one class in 12 patients, by two classes in four patients and remained unchanged in two. Severity of airway collapse improved in 15 and remained unchanged in three patients. The extent of abnormality diminished in 14 patients and did not change in four.

CONCLUSIONS

Using this classification, the morphologies and aetiologies of expiratory central airway collapse are identified, and an objective stratification of patients according to degree of functional impairment, extent of disease and severity of airway collapse is possible.

Tracheobronchomalacia and excessive dynamic airway collapse

Tracheobronchomalacia and excessive dynamic airway collapse are two separate forms of dynamic central airway obstruction that may or may not coexist. These entities are increasingly recognized as asthma and COPD imitators. The understanding of these disease processes, however, has been compromised over the years because of uncertainties regarding their definitions, pathogenesis and aetiology. To date, there is no standardized classification, diagnosis or management algorithm. In this article we comprehensively review the aetiology, morphopathology, physiology, diagnosis and treatment of these entities.

Tracheoplasty for expiratory collapse of central airways

BACKGROUND

Severe central airway obstruction due to expiratory collapse occurs with malacia of intrathoracic trachea and main bronchi, often with chronic obstructive pulmonary disease. Bronchoscopically observed, it is confirmed by inspiratory-expiratory computerized tomographic chest scans. Prior attempts at surgical stabilization have not given dependable results.

METHODS

Posterior tracheobronchial splinting with polypropylene mesh (Marlex) holds cartilages in more normal configuration, and fixes redundant membranous walls. Fourteen consecutive patients were so treated for severe dyspnea. Prior trials of various autologous and exogenous splints failed.

RESULTS

All felt subjectively improved early, with decreased dyspnea, cough, and secretion retention, and with increased activities. Mean forced expiratory volume in 1 second rose from 51% predicted to 73% (p = 0.009), and peak expiratory flow rate from 49% to 70% (p < 0.00001). One patient was lost to follow-up (1 year), 1 died of unrelated cause (5 years), 1 died of chronic obstructive pulmonary disease (3 years), and 1 had decreased respiratory function over 5 years. Ten patients were available for long-term follow-up: 6 were judged to have an excellent result, 2 were good, and 2 were poor due to collapse of unsplinted main bronchi.

CONCLUSIONS

Complete splinting of all malacic central airways with Marlex restores anatomic configuration and permanently prevents expiratory collapse, with relief of extreme dyspnea, cough, and secretion retention.

Cine CT During Coughing for Assessment of Tracheomalacia: Preliminary Experience with 64-MDCT

OBJECTIVE

64-MDCT is advantageous for functional imaging because of its high spatial and temporal resolution combined with its length of coverage. Our purpose is to describe the technical aspects of using 64-MDCT for cine CT during coughing and to share our preliminary clinical experience using this method.

CONCLUSION

This method is technically feasible and offers a promising alternative to previous cine CT methods for diagnosing tracheomalacia.

Tracheal Morphology in Patients With Tracheomalacia

OBJECTIVE

To identify the spectrum of tracheal morphologies in patients with tracheomalacia, and to determine the prevalence of specific inspiratory (lunate) and expiratory (frown) shapes that have been associated with this condition.

MATERIALS AND METHODS

A retrospective review was performed of a consecutive series of patients with bronchoscopically-proven tracheomalacia who were imaged with inspiratory and dynamic-expiratory computed tomography (CT). The CT images of each patient were reviewed in a blinded, randomized fashion by an experienced thoracic radiologist. For each case, the shape of the trachea at end-inspiration and dynamic expiration was classified using specific tracheal morphologies described in the literature.

RESULTS

The study population included 17 patients, with a mean age of 54 years. At inspiration, 16 (94%) of 17 subjects demonstrated a normal tracheal configuration (round, oval, horseshoe, or inverted-pear shape), and 1 (6%) of 17 subjects demonstrated an abnormal "lunate" tracheal configuration (coronal: sagittal ratio >1). At expiration, 9 (53%) of 17 subjects demonstrated a crescenteric, "frown" shape; 1 (6%) subject demonstrated complete collapse; and 7 (41%) subjects demonstrated other morphologies.

CONCLUSIONS

Inspiratory tracheal morphology is almost always normal in patients with tracheomalacia, with a lunate configuration only rarely observed. In contrast, an expiratory "frown sign" is observed in approximately half of patients with this condition. This sign has the potential to aid the detection of tracheomalacia when patients inadvertently breathe during routine CT scans.

Dynamic CT evaluation of the central airways in patients undergoing tracheoplasty for tracheobronchomalacia

OBJECTIVE

The objective of this study was to describe the role of pre- and postoperative dynamic CT in patients undergoing tracheoplasty, a novel surgical method for treatment of severely symptomatic tracheobronchomalacia.

CONCLUSION

Five patients were referred for dynamic MDCT before and after undergoing tracheoplasty at our institution. Preoperatively, all patients showed signs of tracheobronchomalacia (> or = 50% airway collapse) on bronchoscopy, and four (80%) of these five patients showed evidence of malacia on dynamic forceful expiratory CT scans. In all five cases, postoperative CT showed a reduction in the degree of airway collapse during expiration, changes in shape of the trachea during inspiration, and posterior wall thickening related to the procedure. Our preliminary results suggest a potentially important role for CT in the pre- and postoperative assessments of patients with tracheobronchomalacia referred for tracheoplasty.

Tracheobronchomalacia: Comparison between End-expiratory and Dynamic Expiratory CT for Evaluation of Central Airway Collapse

PURPOSE

To compare dynamic expiratory and end-expiratory computed tomography (CT) for depicting central airway collapse in patients with acquired tracheobronchomalacia (TBM).

MATERIALS AND METHODS

Institutional review board approval was obtained, and informed consent was not needed. Retrospective review was performed of all patients with a CT diagnosis of TBM in a 10-month period (n = 34) who underwent evaluation of airway disease by means of three different sequences at multi-detector row CT: end inspiration, dynamic expiration, and end expiration (the latter was performed only at the levels of the aortic arch, carina, and bronchus intermedius). Fourteen patients (11 men, three women; age range, 19-79 years) who had comparable images obtained with all three sequences at any of these three levels were included in the study. The degree of airway collapse was measured by two thoracic radiologists in consensus by calculating the percentage change in the area of the airway between inspiratory and expiratory scanning. Statistical analysis was performed by using the paired t test.

RESULTS

Dynamic expiratory CT elicited a significantly greater degree of airway collapse than end-expiratory CT at all three levels (P < .005). The mean percentages of airway collapse at each of the three levels were as follows: aortic arch, 53.9% with dynamic expiration versus 35.7% with end expiration (P = .0046); carina, 53.6% with dynamic expiration versus 30.9% with end expiration (P < .0001); and bronchus intermedius, 57.5% with dynamic expiration versus 28.6% with end expiration (P = .0022).

CONCLUSION

Dynamic expiratory CT elicits a significantly greater degree of airway collapse than standard end-expiratory CT in patients with TBM.

Tracheomalacia and Tracheobronchomalacia in Children and Adults

Tracheomalacia and tracheobronchomalacia are disorders that are encountered in both pediatric and adult medicine. Despite increasing recognition of these disease processes, there remains some uncertainty regarding their identification, causes, and treatment. This article is intended to be a comprehensive review of both the adult and pediatric forms of the diseases, and includes sections on the historical aspects of the disorders, and their classification, associated conditions, histopathology, and natural history. We also review the various modalities that are used for diagnosis as well as the state of the art of treatment, including airway stent placement and surgical intervention.

Tracheomalacia incidentally detected on CT pulmonary angiography of patients with suspected pulmonary embolism

OBJECTIVE

The aim of this study was to determine the frequency of tracheomalacia incidentally detected on CT pulmonary angiography in patients with suspected pulmonary embolism.

MATERIALS AND METHODS

CT records of 163 consecutive patients imaged with CT pulmonary angiography for suspected pulmonary embolism were retrospectively reviewed at our institution. The patients underwent CT pulmonary angiography with three different types of CT scanners. All images were visually assessed by two thoracic radiologists for excessive collapse of the trachea and the main bronchi. The cross-sectional area of the lumen at the site of maximal collapse of the airway was measured, and the percentage of luminal narrowing was calculated by comparing it with the cross-sectional area of the airway lumen at an adjacent area without collapse. We defined tracheomalacia as a 50% or greater decrease in tracheal lumen.

RESULTS

Sixteen (10%) of 163 patients showed evidence of tracheomalacia (seven men, nine women; age range, 41-95 years; mean age, 72 years). The most common presenting symptom was shortness of breath, which was observed in 13 (81%) of 16 patients. Known causes of tracheomalacia were found in 15 (94%) of 16 patients, prior intubation was confirmed in 12 patients, and history of asthma or chronic obstructive pulmonary disease was observed in five patients.

CONCLUSION

Tracheomalacia is a relatively common incidental finding on CT pulmonary angiography studies. The central airways, as well as pulmonary vasculature, should be reviewed carefully for clinical interpretation in patients with suspected pulmonary embolism. Paired expiratory-inspiratory CT is recommended if patients present with known causes of tracheomalacia such as prior intubation, chronic obstructive pulmonary disease, or asthma.

Tracheobronchomalacia: evolving role of dynamic multislice helical CT

Paired inspiratory and dynamic expiratory multislice CT imaging is a promising method for diagnosing TBM. A low-dose technique should be considered for the dynamic portion to reduce radiation exposure. Visual and quantitative analysis of the central airways provide a comprehensive assessment by allowing for the accurate diagnosis of TBM, determining its extent, assessing for predisposing conditions, and aiding selection of candidates for stent placement or tracheoplasty procedures. This technique can also be helpful for assessing response of airway dynamics following therapeutic intervention.