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

Automatic segmentation and measurement of tracheal collapsibility in tracheomalacia

PURPOSE

To assess feasibility of automated segmentation and measurement of tracheal collapsibility for detecting tracheomalacia on inspiratory and expiratory chest CT images.

METHODS

Our study included 123 patients (age 67 ± 11 years; female: male 69:54) who underwent clinically indicated chest CT examinations in both inspiration and expiration phases. A thoracic radiologist measured anteroposterior length of trachea in inspiration and expiration phase image at the level of maximum collapsibility or aortic arch (in absence of luminal change). Separately, another investigator separately processed the inspiratory and expiratory DICOM CT images with Airway Segmentation component of a commercial COPD software (IntelliSpace Portal, Philips Healthcare). Upon segmentation, the software automatically estimated average lumen diameter (in mm) and lumen area (sq.mm) both along the entire length of trachea and at the level of aortic arch. Data were analyzed with independent t-tests and area under the receiver operating characteristic curve (AUC).

RESULTS

Of the 123 patients, 48 patients had tracheomalacia and 75 patients did not. Ratios of inspiration to expiration phases average lumen area and lumen diameter from the length of trachea had the highest AUC of 0.93 (95% CI = 0.88-0.97) for differentiating presence and absence of tracheomalacia. A decrease of ≥25% in average lumen diameter had sensitivity of 82% and specificity of 87% for detecting tracheomalacia. A decrease of ≥40% in the average lumen area had sensitivity and specificity of 86% for detecting tracheomalacia.

CONCLUSION

Automatic segmentation and measurement of tracheal dimension over the entire tracheal length is more accurate than a single-level measurement for detecting tracheomalacia.

Tracheobronchomalacia and Excessive Dynamic Airway Collapse: Current Concepts and Future Directions

Tracheobronchomalacia (TBM) and excessive dynamic airway collapse (EDAC) are airway abnormalities that share a common feature of expiratory narrowing but are distinct pathophysiologic entities. Both entities are collectively referred to as expiratory central airway collapse (ECAC). The malacia or weakness of cartilage that supports the tracheobronchial tree may occur only in the trachea (ie, tracheomalacia), in both the trachea and bronchi (TBM), or only in the bronchi (bronchomalacia). On the other hand, EDAC refers to excessive anterior bowing of the posterior membrane into the airway lumen with intact cartilage. Clinical diagnosis is often confounded by comorbidities including asthma, chronic obstructive pulmonary disease, obesity, hypoventilation syndrome, and gastroesophageal reflux disease. Additional challenges include the underrecognition of ECAC at imaging; the interchangeable use of the terms TBM and EDAC in the literature, which leads to confusion; and the lack of clear guidelines for diagnosis and treatment. The use of CT is growing for evaluation of the morphology of the airway, tracheobronchial collapsibility, and extrinsic disease processes that can narrow the trachea. MRI is an alternative tool, although it is not as widely available and is not used as frequently for this indication as is CT. Together, these tools not only enable diagnosis, but also provide a road map to clinicians and surgeons for planning treatment. In addition, CT datasets can be used for 3D printing of personalized medical devices such as stents and splints. An invited commentary by Brixey is available online. Online supplemental material is available for this article. ^©RSNA, 2022.

Detection and diagnosis of large airway collapse: a systematic review

Large airway collapse (LAC) is a frequently encountered clinical problem, caused by tracheobronchomalacia +/− excessive dynamic airway collapse, yet there are currently no universally accepted diagnostic criteria. We systematically reviewed studies reporting a diagnostic approach to LAC in healthy adults and patients, to compare diagnostic modalities and criteria used. Electronic databases were searched for relevant studies between 1989 and 2019. Studies that reported a diagnostic approach using computed tomography (CT), magnetic resonance imaging or flexible fibreoptic bronchoscopy were included. Random effects meta-analyses were performed to estimate the prevalence of LAC in healthy subjects and in patients with chronic obstructive airway diseases. We included 41 studies, describing 10 071 subjects (47% female) with a mean±sd age of 59±9 years. Most studies (n=35) reported CT findings, and only three studies reported bronchoscopic findings. The most reported diagnostic criterion was a ≥50% reduction in tracheal or main bronchi calibre at end-expiration on dynamic expiratory CT. Meta-analyses of relevant studies found that 17% (95% CI: 0–61%) of healthy subjects and 27% (95% CI: 11–46%) of patients with chronic airways disease were classified as having LAC, using this threshold. The most reported approach to diagnose LAC utilises CT diagnostics, and at a threshold used by most clinicians (i.e., ≥50%) may classify a considerable proportion of healthy individuals as being abnormal and having LAC in a quarter of patients with chronic airways disease. Future work should focus on establishing more precise diagnostic criteria for LAC, relating this to relevant physiological and disease sequelae.

CT is mostly used to diagnose LAC, and at a threshold used by most clinicians (i.e. ≥50%) that would classify a large proportion of healthy individuals as being abnormal and LAC in a quarter of patients with chronic airway diseaseshttps://bit.ly/3izAuSk

Chronic Vaping Related Tracheomalacia (TM): A Case of Vaping Induced Altered Innate Immunity that Culminated in Severe TM

Tracheomalacia (TM) is a weakness of the trachea either due to impaired cartilage integrity or atrophy of muscular elastic fibers. We present the first-ever case of chronic vaping induced altered immunological defenses that led to frequent pulmonary infections, ultimately culminating in severe TM which we successfully treated with positive airway pressure (PAP) therapy. A 53-year-old male presented with hypoxia and pneumonia refractory to outpatient antibiotics and steroids. He underwent bronchoscopy which showed severe TM, prompting transfer to our institution. He started vaping seven years ago and noted frequent bronchitis requiring antibiotics and steroids along with 10 life-time surgeries. He underwent repeat bronchoscopy noting TM, worst 3 cm above the carina and extending 4 cm proximally. The lesion was deemed not suitable for stenting, so PAP therapy was initiated. Bronchoalveolar lavage (BAL) confirmed 40% alveolar macrophages positive for lipid in Oil-O-Red stain consistent with EVALI. He tolerated PAP therapy with significant improvement in his ground glass opacities (GGO) and TM on subsequent imaging. TM is generally defined as >50% narrowing in the sagittal diameter. It is often further characterized into primary (congenital) or secondary (acquired) causes. Notable secondary causes include postintubation, chronic infection/bronchitis, chronic inflammation, and frequent steroid exposure -- all present in this case. Furthermore, there is existing literature that chronic inflammation due to irritants like cigarette smoke may be an important contributor to the development of TM. However, such data are lacking for EVALI. Our patient started experiencing repeated bronchitis episodes after he started vaping, leading to chronic inflammation and frequent antibiotics/steroids. Given his additional risk factor of multiple surgeries, this case not only presents a perfect storm for TM, but also a novel manifestation of EVALI. This case, to our knowledge, is the first-ever manifestation of EVALI presenting with TM. Management with PAP therapy helped avoid major surgery.

"Tracheomalacia after Thyroidectomy," Does it Truly Exist?

Aim:

Tracheomalacia is a potentially life-threatening, but a rare complication of thyroidectomy. In previous studies, the incidence rate was very different. Considering the relatively high prevalence of goiter and thyroidectomy in the West Azerbaijan region, we designed this study to determine the tracheomalacia incidence in patients who underwent thyroidectomy within a 10-year interval.

Materials and Methods:

This retrospective study was done in Urmia Imam Khomeini Hospital in West Azarbayjan Province. Demographic characteristics including the age and sex of patients who underwent thyroidectomy between 2007 and 2017 and also the incidence of tracheomalacia after surgery were recorded.

Results:

From 2007 to 2017, total 1236 thyroidectomy were performed. The patients’ age ranged from 15 to 83-year-old with a mean age of patients was 44.5 ± 13.81 years old. Two hundred and twenty-nine patients (19%) were male and 1007 (81%) were female. We did not find any cases of tracheomalacia after thyroidectomy in our study population.

Conclusion:

Based on the results of this study, it seems that with the necessary precautions, the incidence of tracheomalacia can reach zero.

Paratracheal Paraseptal Emphysema and Expiratory Central Airway Collapse in Smokers

RATIONALE

Expiratory central airway collapse is associated with respiratory morbidity independent of underlying lung disease. However, not all smokers develop expiratory central airway collapse, and the etiology of expiratory central airway collapse in adult smokers is unclear. Paraseptal emphysema in the paratracheal location, by untethering airway walls, may predispose smokers to developing expiratory central airway collapse.

OBJECTIVES

To evaluate whether paratracheal paraseptal emphysema is associated with expiratory central airway collapse.

METHODS

We analyzed paired inspiratory and expiratory computed tomography scans from participants enrolled in a multicenter study (Genetic Epidemiology of Chronic Obstructive Pulmonary Disease) of smokers aged 45 to 80 years. Expiratory central airway collapse was defined as greater than or equal to 50% reduction in cross-sectional area of the trachea during expiration. In a nested case-control design, participants with and without expiratory central airway collapse were included in a 1:2 fashion, and inspiratory scans were further analyzed using the Fleischner Society criteria for presence of centrilobular emphysema, paraseptal emphysema, airway wall thickening, and paratracheal paraseptal emphysema (maximal diameter ≥ 0.5 cm).

RESULTS

A total of 1,320 patients were included, 440 with and 880 without expiratory central airway collapse. Those with expiratory central airway collapse were older, had higher body mass index, and were less likely to be men or current smokers. Paratracheal paraseptal emphysema was more frequent in those with expiratory central airway collapse than control subjects (16.6 vs. 11.8%; P = 0.016), and after adjustment for age, race, sex, body mass index, smoking pack-years, and forced expiratory volume in 1 second, paratracheal paraseptal emphysema was independently associated with expiratory central airway collapse (adjusted odds ratio, 1.53; 95% confidence interval, 1.18-1.98; P = 0.001). Furthermore, increasing size of paratracheal paraseptal emphysema (maximal diameter of at least 1 cm and 1.5 cm) was associated with greater odds of expiratory central airway collapse (adjusted odds ratio, 1.63; 95% confidence interval, 1.18-2.25; P = 0.003 and 1.77; 95% confidence interval, 1.19-2.64; P = 0.005, respectively).

CONCLUSIONS

Paraseptal emphysema adjacent to the trachea is associated with expiratory central airway collapse. The identification of this risk factor on inspiratory scans should prompt further evaluation for expiratory central airway collapse. Clinical trial registered with ClinicalTrials.gov (NCT 00608764).

First series of minimally invasive, robot-assisted tracheobronchoplasty with mesh for severe tracheobronchomalacia

OBJECTIVE

Tracheobronchomalacia is a progressive, debilitating disease with limited treatment options. Open tracheobronchoplasty (TBP) is an accepted surgical option for management of severe tracheobronchomalacia. This study examined the outcomes of the first reported series of robot-assisted TBP (R-TBP).

METHODS

We retrospectively reviewed the records of patients with clinical suspicion for tracheobronchomalacia who had dynamic computed tomography scan and subsequent R-TBP from May 2016 to December 2017.

RESULTS

Four hundred thirty-five patients underwent dynamic computed tomography scan for suspicion of tracheobronchomalacia. Of this group, 42 patients underwent R-TBP. In the surgery group, the median age was 66 years (interquartile range, 39-72 years) and there were 30 women (71%). Respiratory comorbidities included asthma (88%) and chronic obstructive pulmonary disease (52%). The median operative time was 249 minutes (interquartile range, 266-277 minutes). Median hospital length of stay was 3 days (interquartile range, 2-4.75 days), and there were 19 postoperative complications (11 minor and 8 major). There were no mortalities at 90 days. Comparison of preoperative and postoperative pulmonary function testing demonstrated improvement in forced expiratory volume at 1 second by 13.5% (P = .01), forced vital capacity by 14.5% (P < .0001), and peak expiratory flow rate by 21.0% (P < .0001). Quality of life questionnaires also showed improvement with 82% reporting overall satisfaction with the procedure.

CONCLUSIONS

R-TBP can be performed with low morbidity and mortality. Early follow-up reveals significant improvement in pulmonary function testing and high patient satisfaction when compared with preoperative baseline. Long-term follow-up is needed to demonstrate the durability of R-TBP and substantiate its role in the management of patients with symptomatic, severe tracheobronchomalacia.

Is silicone stent insertion a clinically useful option for tracheobronchomalacia?

BACKGROUND/AIM

Tracheobronchomalacia (TBM) leads to the obstruction of expiratory airflow and interference with secretion clearance. Stabilization of the airway wall using a silicon stent or laser coagulation of the posterior wall may be treatment options. This study aimed to retrospectively analyze which interventional bronchoscopic method could be used to provide airway stabilization and gain control of symptoms and for whom this method could be used.

MATERIALS AND METHODS

Fifteen patients who had received treatment in our interventional pulmonology unit were analyzed. We analyzed the techniques used, stent duration, complications, and long-term treatment success retrospectively.

RESULTS

Stents were used in 10 patients: 4 patients had silicon Y-stents and 4 patients had silicon tracheal stents. Stents were removed due to early migration in 3 patients. In 5 of the 7 cases, the stent was removed due to frequent obstructions of the stent due to recurrent severe mucostasis. A suitable stent was not found for one patient who had an extremely enlarged trachea. Good clinical results were achieved in just two cases. The frequency of admissions to the emergency room and hospitalizations were diminished during the follow-up time in these two patients.

CONCLUSION

Silicon stents may be a good treatment option in selected patients with TBM and dynamic collapse. However, our patients were high-risk; thus, the criteria for candidates for bronchoscopic treatment should be carefully defined.

Association Between Expiratory Central Airway Collapse and Respiratory Outcomes Among Smokers

IMPORTANCE

Central airway collapse greater than 50% of luminal area during exhalation (expiratory central airway collapse [ECAC]) is associated with cigarette smoking and chronic obstructive pulmonary disease (COPD). However, its prevalence and clinical significance are unknown.

OBJECTIVE

To determine whether ECAC is associated with respiratory morbidity in smokers independent of underlying lung disease.

DESIGN, SETTING, AND PARTICIPANTS

Analysis of paired inspiratory-expiratory computed tomography images from a large multicenter study (COPDGene) of current and former smokers from 21 clinical centers across the United States. Participants were enrolled from January 2008 to June 2011 and followed up longitudinally until October 2014. Images were initially screened using a quantitative method to detect at least a 30% reduction in minor axis tracheal diameter from inspiration to end-expiration. From this sample of screen-positive scans, cross-sectional area of the trachea was measured manually at 3 predetermined levels (aortic arch, carina, and bronchus intermedius) to confirm ECAC (>50% reduction in cross-sectional area).

EXPOSURES

Expiratory central airway collapse.

MAIN OUTCOMES AND MEASURES

The primary outcome was baseline respiratory quality of life (St George's Respiratory Questionnaire [SGRQ] scale 0 to 100; 100 represents worst health status; minimum clinically important difference [MCID], 4 units). Secondary outcomes were baseline measures of dyspnea (modified Medical Research Council [mMRC] scale 0 to 4; 4 represents worse dyspnea; MCID, 0.7 units), baseline 6-minute walk distance (MCID, 30 m), and exacerbation frequency (events per 100 person-years) on longitudinal follow-up.

RESULTS

The study included 8820 participants with and without COPD (mean age, 59.7 [SD, 6.9] years; 4667 [56.7%] men; 4559 [51.7%] active smokers). The prevalence of ECAC was 5% (443 cases). Patients with ECAC compared with those without ECAC had worse SGRQ scores (30.9 vs 26.5 units; P < .001; absolute difference, 4.4 [95% CI, 2.2-6.6]) and mMRC scale scores (median, 2 [interquartile range [IQR], 0-3]) vs 1 [IQR, 0-3]; P < .001]), but no significant difference in 6-minute walk distance (399 vs 417 m; absolute difference, 18 m [95% CI, 6-30]; P = .30), after adjustment for age, sex, race, body mass index, forced expiratory volume in the first second, pack-years of smoking, and emphysema. On follow-up (median, 4.3 [IQR, 3.2-4.9] years), participants with ECAC had increased frequency of total exacerbations (58 vs 35 events per 100 person-years; incidence rate ratio [IRR], 1.49 [95% CI, 1.29-1.72]; P < .001) and severe exacerbations requiring hospitalization (17 vs 10 events per 100 person-years; IRR, 1.83 [95% CI, 1.51-2.21]; P < .001).

CONCLUSIONS AND RELEVANCE

In a cross-sectional analysis of current and former smokers, the presence of ECAC was associated with worse respiratory quality of life. Further studies are needed to assess long-term associations with clinical outcomes.

S2e guideline: positioning and early mobilisation in prophylaxis or therapy of pulmonary disorders : Revision 2015: S2e guideline of the German Society of Anaesthesiology and Intensive Care Medicine (DGAI)

The German Society of Anesthesiology and Intensive Care Medicine (DGAI) commissioneda revision of the S2 guidelines on "positioning therapy for prophylaxis or therapy of pulmonary function disorders" from 2008. Because of the increasing clinical and scientificrelevance the guidelines were extended to include the issue of "early mobilization"and the following main topics are therefore included: use of positioning therapy and earlymobilization for prophylaxis and therapy of pulmonary function disorders, undesired effects and complications of positioning therapy and early mobilization as well as practical aspects of the use of positioning therapy and early mobilization. These guidelines are the result of a systematic literature search and the subsequent critical evaluation of the evidence with scientific methods. The methodological approach for the process of development of the guidelines followed the requirements of evidence-based medicine, as defined as the standard by the Association of the Scientific Medical Societies in Germany. Recently published articles after 2005 were examined with respect to positioning therapy and the recently accepted aspect of early mobilization incorporates all literature published up to June 2014.

Airway obstruction due to tracheomalacia caused by innominate artery compression and a kyphotic cervical spine

Tracheomalacia can cause variable degrees of intrathoracic airway obstruction and is an easily overlooked cause of respiratory distress in adults. Here, we report a case of acute respiratory failure in which subglottic stenosis was accidentally identified during endotracheal intubation. Subsequent bronchoscopy and computed tomography of the thorax and neck revealed tracheal compression with tracheomalacia caused by a tortuous innominate artery and a kyphotic cervical spine. The patient underwent rigid bronchoscopy with metal stent implantation, and her symptoms were alleviated. These findings outline the importance of precise diagnosis and interventions for preventing recurrent life-threatening respiratory failure in such cases.

A surprising cause of wheezing in a morbidly obese patient: a case report

A typical patient with chronic obstructive pulmonary disease has small airway disease, which often responds to bronchodilators. If the patient is obese, he or she may be further compromised and not tolerate being in the supine position. We present a case of a patient with history of chronic obstructive pulmonary disease and obstructive sleep apnea with acute renal failure and urosepsis scheduled for an emergent debridement of Fournier's gangrene. In this patient, the fiberoptic intubation was performed in semi-Fowler's position, and tracheomalacia was observed.

To breathe or not to breathe: a review of artificial airway placement and related complications

Artificial airway devices are commonly used to provide adequate ventilation and/or oxygenation in multiple clinical settings, both emergent and nonemergent. These frequently used devices include laryngeal mask airway, esophageal-tracheal combitube, endotracheal tube, and tracheostomy tube and are associated with various acute and late complications. Clinically, this may vary from mild discomfort to a potentially life-threatening situation. Radiologically, these devices and their acute and late complications have characteristic imaging findings which can be detected primarily on radiographs and computed tomography. We review appropriate positioning of these artificial airway devices and illustrate associated complications including inadequate positioning of the endotracheal tube, pulmonary aspiration, tracheal laceration or perforation, paranasal sinusitis, vocal cord paralysis, post-intubation tracheal stenosis, cuff overinflation with vascular compression, and others. Radiologists must recognize and understand the potential complications of intubation to promptly guide management and avoid long-term or even deadly consequences.

Prevalence of tracheobronchomalacia and excessive dynamic airway collapse in bronchial asthma of different severity

Background

Tracheobronchomalacia (TBM) is a pathologic condition in which softening of tracheal and bronchial cartilage causes the dynamic narrowing of transverse or sagittal diameters of tracheobronchial lumen; an excessive dynamic airway collapse (EDAC) may also be associated, with a substantial invagination of the posterior membrane of trachebronchial tree.

The aim of this study was to assess the prevalence of both TBM and EDAC in a population of asthmatics with different degrees of disease severity compared to a reference group of subjects without any bronchial obstruction.

Methods

A cohort of 202 asthmatics was investigated by means of a dynamic flexible videobronchoscopy: 74 mild persistent (MPA - age 18–68 ys; 35 males; mean FEV₁ = 88.6% pred. ± 8.3 sd); 63 moderate (MA - age 21–71 ys; 30 males; mean FEV₁ = 71.3% pred. ± 9.1 sd), 65 severe asthmatics (SA - age 33–70 ys; 25 males; mean FEV₁ = 48.5% pred. ± 7.6 sd), and 62 non obstructed subjects (NO - age 18–71 ys; 38 males; mean FEV₁ 98.6% pred. ± 2.7 sd). TBM and EDAC were classified according to FEMOS classification.

Results

TBM and EDAC were observed in only 1/62 subjects (both 1.61%) of NO group, while their prevalence was 2.70% and 6.75% in MPA group; 7.93% and 19.04% in MA group; 18.46% and 69.23% in SA group, respectively. The crude prevalence of thyroid disorders in the population was 12.9%. In particular, the prevalence of thyroid disorders was significantly higher in females than in men, but 54-fold higher in females than in men in the presence of EDAC.

Conclusions

1) The prevalence of both TBM and EDAC is directly related to age, gender (females), and asthma severity; 2) EDAC is much more frequent than TBM in all asthma patients; 3) both tracheal abnormalities proved to be more represented in asthmatics with thyroid disorders, and particularly in female asthmatics with EDAC.

Incidental findings in imaging diagnostic tests: a systematic review

The objective of this review is to summarise the available evidence on the frequency and management of incidental findings in imaging diagnostic tests. Original articles were identified by a systematic search of the MEDLINE, EMBASE and Cochrane Library Plus databases using appropriate medical headings. Extracted variables were study design; sample size; type of imaging test; initial diagnosis; frequency and location of incidental findings; whether clinical follow-up was performed; and whether a definitive diagnosis was made. Study characteristics were assessed by one reviewer and checked by a second reviewer. Any disagreement was solved by consensus. The relationship between the frequency of incidental findings and the study characteristics was assessed using a one-way ANOVA test, as was the frequency of follow-up of incidental findings and the frequency of confirmation. 251 potentially relevant abstracts were identified and 44 articles were finally included in the review. Overall, the mean frequency of incidental findings was 23.6% (95% confidence interval (CI) 15.8-31.3%). The frequency of incidental findings was higher in studies involving CT technology (mean 31.1%, 95% CI 20.1-41.9%), in patients with an unspecific initial diagnosis (mean 30.5, 95% CI 0-81.6) and when the location of the incidental findings was unspecified (mean 33.9%, 95% CI 18.1-49.7). The mean frequency of clinical follow-up was 64.5% (95% CI 52.9-76.1%) and mean frequency of clinical confirmation was 45.6% (95% CI 32.1-59.2%). Although the optimal strategy for the management of these abnormalities is still unclear, it is essential to be aware of the low clinical confirmation in findings of moderate and major importance.

Incidence of tracheobronchomalacia associated with pulmonary emphysema: detection with paired inspiratory-expiratory multidetector computed tomography using a low-dose technique

PURPOSE

The purpose of this study was to evaluate the frequency of tracheobronchomalacia (TBM) associated with pulmonary emphysema with paired inspiratory-expiratory multidetector computed tomography (MDCT) using a low-dose technique.

MATERIALS AND METHODS

This study included 56 consecutive patients (55 men, 1 woman; mean age 68.9 years) with pulmonary emphysema who had undergone paired inspiratory-expiratory CT scanning with a low-dose technique (40 mA). All images were retrospectively examined by two thoracic radiologists in a blinded fashion. The diagnosis of TBM was based on the standard criterion of >50% reduction in the cross-sectional area of the tracheobronchial lumen at the end-expiratory phase. A mild TBM criterion of >30% reduction was also reviewed. All patients underwent pulmonary function tests. The relation between the forced expiratory volume in 1 s (FEV(1.0%)) and TBM was statistically analyzed.

RESULTS

Four (7.1%) and eight (14.3%) patients were diagnosed as TBM based on the standard and mild criteria, respectively. In four patients, the percentages of luminal narrowing were 63.4% and 51.2%, respectively for tracheomalacia and 59.2% and 62.0%, respectively, for bronchomalacia. The FEV(1.0%) values between patients with and without TBM showed no statistical difference.

CONCLUSION

The incidence of TBM associated with pulmonary emphysema was 7.1% with the standard criterion. It is possible that TBM has been underdiagnosed in a number of patients with pulmonary emphysema.

Prevalence of tracheal collapse in an emphysema cohort as measured with end-expiration CT

RATIONALE AND OBJECTIVES

To retrospectively investigate the prevalence of tracheal collapse in an emphysema cohort. The occurrence of a large degree of tracheal collapse may have important implications for the clinical management of respiratory symptoms and air trapping in patients with emphysema.

MATERIALS AND METHODS

Paired full-inspiratory and end-expiratory thin-section volumetric computed tomographic scans were available for 1071 long-term smokers with clinically and physiologically confirmed emphysema. The percentage reduction in the cross-sectional tracheal luminal area from full-inspiration to end-expiration was automatically computed at 2.5-mm intervals along the centerline of the trachea using customized software.

RESULTS

Maximal tracheal collapse did not follow a normal distribution in the emphysema cohort (P < .0001, skewness/kurtosis tests for normality); the median collapse was 18% (intraquartile range, 11%-30%). Statistically significant differences were found in the distribution of maximal collapse by gender (P < .005, Wilcoxon rank sum test). Overall, 10.5% of men and 17.1% of women showed evidence of tracheomalacia on the basis of the criterion of a reduction of 50% or greater in cross-sectional tracheal luminal area at end-expiration.

CONCLUSION

This study offers insights into the prevalence of tracheal collapse in a cohort of patients with emphysema; future work is needed to determine the possible relationship between tracheal collapse and air trapping in subjects with emphysema.

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.

Incidental findings in the maxillofacial area with 3-dimensional cone-beam imaging

INTRODUCTION

The purposes of this study were to evaluate the location, nature, and occurrence of incidental findings in maxillofacial structures on 3-dimensional cone-beam volumetric scans done for dental diagnostic purposes and to look for associations between these findings and symptoms in orthodontic patients.

METHODS

Images from 500 consecutive maxillofacial 3-dimensional scans were examined. The patient sample consisted of 252 orthodontic patients, 172 implant patients, 33 endodontic patients, 34 temporomandibular joint (TMJ) disorder patients, and 10 others.

RESULTS

The overall rate of incidental findings was 24.6% (123 patients of 500). The highest rate of incidental findings was in the airway area (18.2%), followed by TMJ findings (3.4%), endodontic findings (1.8%), and others (1.2%). In the orthodontic group, the incidences were airway findings, 21.4%; TMJ findings, 5.6%; and endodontic lesions, 2.3%. Only 22% of the airway findings, such as mucosal thickness, polyps, and retention cysts, were correlated with clinical signs and symptoms.

CONCLUSIONS

For clinical diagnosis, the data should be interpreted with a full history of clinical signs and symptoms, and with detailed communications with radiological colleagues and other specialists to comprehensively evaluate possible underlying diseases.

Comparison of Dynamic Expiratory CT With Bronchoscopy for Diagnosing Airway Malacia: A Pilot Evaluation

OBJECTIVE

To assess the accuracy of dynamic expiratory CT for detecting airway malacia using bronchoscopy as the diagnostic "gold standard."

MATERIALS AND METHODS

A computerized hospital information system was used to retrospectively identify all patients with bronchoscopically proven airway malacia referred for CT airway imaging at our institution during a 19-month period. CT was performed within 1 week of bronchoscopy. All patients were scanned with a standard protocol, including end-inspiratory and dynamic expiratory volumetric imaging, using an eight-detector multislice helical CT scanner. For both CT and bronchoscopy, malacia was defined as >/= 50% expiratory reduction of the airway lumen. CT and bronchoscopic findings were subsequently jointly reviewed by the radiologist and bronchoscopist for concordance.

RESULTS

Twenty-nine patients (12 men and 17 women; mean age, 60 years; range, 36 to 79 years) comprised the study cohort. CT correctly diagnosed malacia in 28 of 29 patients (97%). The most common presenting symptoms were dyspnea in 20 patients (69%), severe or persistent cough in 16 patients (55%), and recurrent infection in 7 patients (24%). The estimated radiation dose (expressed as dose-length product) for the dual-phase study is 508 mGy-cm, which is comparable to a routine chest CT.

CONCLUSION

Dynamic expiratory CT is a highly sensitive method for detecting airway malacia and has the potential to serve as an effective, noninvasive test for diagnosing this condition.

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.

Stenting at the Flow-limiting Segment in Tracheobronchial Stenosis due to Lung Cancer

Airway stenting at the wave-speed flow-limiting segment (the choke point) is assessed. We determined prospectively the precise location of the choke point using the flow-volume curve, endobronchial ultrasonography, ultrathin bronchoscopy, and three-dimensional computed tomography scan before and after stenting in 64 patients with extrincic compression due to lung cancer. We noted distinct flow-volume curve patterns specific to the type of stenosis. The tracheal stenosis group indicated fixed narrowing patterns with an expiratory plateau, bronchial stenosis group dynamic collapse patterns with an expiratory flow deterioration (choking), carinal stenosis group combined fixed and dynamic patterns, and extensive stenosis group complex patterns containing elements of all the former. After stenting, almost full-function patterns with significant improvement in PEF were observed in all groups (p < 0.01, p < 0.05, p < 0.001, p < 0.01, respectively). In patients with extensive stenosis, implantation of additional stents was required when the choke points were observed to have migrated to the areas of malacia with cartilage destruction by the tumor. Secondary stenting at migrated choke points resulted in a significant improvement in PEF over the initial stenting (p < 0.01). Stenting at the choke point improved expiratory flow limitation by increasing the cross-sectional area, supporting the weakened airway wall and relieving dyspnea.