Grading Airway Stenosis Down to the Segmental Level Using Virtual Bronchoscopy

Balloon Bronchoplasty for the Treatment of Bronchial Stenosis After Lung Transplantation: A Single-Center 10-Year Experience

OBJECTIVE

To assess the safety and efficacy of balloon dilatation under dual guidance using fluoroscopy and bronchoscopy for treating bronchial stenosis following lung transplantation (LT), and to elucidate the factors associated with patency after the procedure.

MATERIALS AND METHODS

From September, 2012, to April, 2021, 50 patients (mean age ± standard deviation, 54.4 ± 12.2 years) with bronchial stenosis among 361 recipients of LT were retrospectively analyzed. The safety of balloon dilatation was assessed by evaluating procedure-related complications. Efficacy was assessed by evaluating the technical success, primary patency, and secondary patency. Primary and secondary cumulative patency rates were calculated using the Kaplan-Meier method. The factors associated with patency after the procedure were evaluated using multivariable Cox hazard proportional regression analysis.

RESULTS

In total, 65 bronchi were treated with balloon dilatation in 50 patients. The total number of treatment sessions was 277 and the technical success rate was 99.3% (275/277 sessions). No major procedure-related complications were noted. During the mean follow-up period of 34.6 ± 30.8 months, primary patency was achieved in 12 of 65 bronchi (18.5%). However, the patency rate improved to 76.9% (50 of 65 bronchi) after repeated balloon dilatation (secondary patency). The 6-month, 1-year, 3-year, and 5-year secondary patency rates were 95.4%, 90.8%, 83.1%, and 78.5%, respectively. The presence of clinical symptoms was a significant prognostic factor associated with reduced primary patency (adjusted hazard ratio [HR], 0.465; 95% confidence interval [CI], 0.220-0.987). Early-stage treatment ≤ 6 months (adjusted HR, 3.588; 95% CI, 1.093-11.780) and prolonged balloon dilatation > 5 min (adjusted HR, 3.285; 95% CI, 1.018-10.598) were associated with significantly higher secondary patency.

CONCLUSION

Repeated balloon dilatation was determined to be safe and effective for treating bronchial stenosis following LT. Early-stage treatment and prolonged balloon dilatation could significantly promote long-term patency.

Novel airway-cartilage combined model for medialization laryngoplasty and laryngotracheal reconstruction surgery planning

BACKGROUND

The clinical outcomes of surgical treatments for vocal cord paralysis and tracheal stenosis, such as medialization laryngoplasty and laryngotracheal reconstruction, vary owing to the complex anatomy and physiology of the human upper airway. However, advances in three-dimensional (3D) simulation and printing ushered its use on an office-based workstation to aid in several surgical areas.

METHODS

The preoperation neck computed tomography image was loaded into the InVesalius 3.0 software for manual segmentation of airway and nearby important anatomic landmarks including hyoid bone, thyroid cartilage, and cricoid cartilage. The 3D model of the desired anatomy structure was manufactured and used for presurgical planning and rehearsal of the surgery.

RESULTS

We review cases of four patients: two cases of unilateral vocal palsy undergoing medialization laryngoplasty and two cases of tracheal stenosis patients who used the air-cartilage combined model.

CONCLUSION

Preoperation planning of the medialization thyroplasty could be more precise by prevision of the paralyzed vocal cord plane. Tracheal surgery could benefit from a preoperative design of segmented length. The novel airway-cartilage combined model offers new insight into vocal cord and trachea surgery.

How Nanoparticle Aerosols Transport through Multi-Stenosis Sections of Upper Airways: A CFD-DPM Modelling

Airway stenosis is a global respiratory health problem that is caused by airway injury, endotracheal intubation, malignant tumor, lung aging, or autoimmune diseases. A precise understanding of the airflow dynamics and pharmaceutical aerosol transport through the multi-stenosis airways is vital for targeted drug delivery, and is missing from the literature. The object of this study primarily relates to behaviors and nanoparticle transport through the multi-stenosis sections of the trachea and upper airways. The combination of a CT-based mouth–throat model and Weibel’s model was adopted in the ANSYS FLUENT solver for the numerical simulation of the Euler–Lagrange (E-L) method. Comprehensive grid refinement and validation were performed. The results from this study indicated that, for all flow rates, a higher velocity was usually found in the stenosis section. The maximum velocity was found in the stenosis section having a 75% reduction, followed by the stenosis section having a 50% reduction. Increasing flow rate resulted in higher wall shear stress, especially in stenosis sections. The highest pressure was found in the mouth–throat section for all flow rates. The lowest pressure was usually found in stenosis sections, especially in the third generation. Particle escape rate was dependent on flow rate and inversely dependent on particle size. The overall deposition efficiency was observed to be significantly higher in the mouth–throat and stenosis sections compared to other areas. However, this was proven to be only the case for a particle size of 1 nm. Moreover, smaller nanoparticles were usually trapped in the mouth–throat section, whereas larger nanoparticle sizes escaped through the lower airways from the left side of the lung; this accounted for approximately 50% of the total injected particles, and 36% escaped from the right side. The findings of this study can improve the comprehensive understanding of airflow patterns and nanoparticle deposition. This would be beneficial in work with polydisperse particle deposition for treatment of comprehensive stenosis with specific drugs under various disease conditions.

Diagnostic Value of Virtual Bronchoscopic Navigation in the Bronchial Tuberculosis Induced Central Airway Stenosis

Introduction

Electronic bronchoscopy is invasive and may cause pain. This study aimed to explore the clinical value of virtual bronchoscopic navigation (VBN) in the diagnosis of benign central airway stenosis (CAS) secondary to tracheobronchial tuberculosis (TBT).

Methods

Sixty-eight patients with benign CAS caused by TBT were recruited between July 2015 and December 2017. The location, length and diameter of stenoses were independently determined by VBN and electronic bronchoscopy (EOB), and the sensitivity and specificity of VBN in identifying stenosis were assessed with EOB as the gold standard.

Results

In 68 patients with TBT, the overall coincidence between EOB and VBN in the identification of stenosis was 100%. A total of 188 sites were selected from the central airway, and the stenosis was graded into 0%, ≤ 25%, 26–50%, 51–75%, 76–90% and > 90%. The sensitivity of VBN in determining the degree of stenosis was 98.45%, 100.00%, 100.00%, 100.00%, 84.62% and 0.00%, respectively; the specificity was 91.53%, 96.07%, 97.09%, 97.08%, 97.14% and 97.30%, respectively; the accuracy rate was 96.28%, 96.28%, 97.34%, 97.34%, 96.28% and 95.7%, respectively. The length of airway stenosis on EOB was divided into < 10 mm, 10–30 mm, 30–50 mm and > 50 mm. There was no significant difference in the length of airway stenosis between VBN and EOB (t = 0.083, P = 0.936; t = 1.340, P = 0.199; t = 1.297, P = 0.216; t = 2.186, P = 0.081). In three patients who received stent placement, VBN was able to accurately assess the postoperative expansion.

Conclusion

VBN is helpful for the diagnosis of TBT-induced CBS and may provide important information on the location, length, diameter and cross-sectional area of stenosis for further EOB examination and interventional therapy. VBN is recommended for patients with TBT and those with contradictions to bronchoscopy, as well as for regular follow-up of stable TBT, because it reduces the incidence of injury, avoids repeat operations and shortens treatment time.

Predicted airway obstruction distribution based on dynamical lung ventilation data: A coupled modeling-machine learning methodology

In asthma and chronic obstructive pulmonary disease, some airways of the tracheobronchial tree can be constricted, from moderate narrowing up to closure. Those pathological patterns of obstructions affect the lung ventilation distribution. While some imaging techniques enable visualization and quantification of constrictions in proximal generations, no noninvasive technique exists to provide the airway morphology and obstruction distribution in distal areas. In this work, we propose a method that exploits lung ventilation measures to access positions of airway obstructions (restrictions and closures) in the tree. This identification approach combines a lung ventilation model, in which a 0D tree is strongly coupled to a 3D parenchyma description, along with a machine learning approach. On the basis of synthetic data generated with typical temporal and spatial resolutions as well as reconstruction errors, we obtain very encouraging results of the obstruction distribution, with a detection rate higher than 85%.

Intrabronchial display of hilar-mediastinal lymph nodes by virtual bronchoscopic navigation system

The description of precise intrabronchial positions for the sampling of mediastinal‐hilar lymph nodes is critical to successfully perform conventional transbronchial needle aspiration. Previously published maps of mediastinal‐hilar lymph nodes were primarily drawn based on experts’ experience. We generated a virtual map of the most frequently sampled intrathoracic lymph nodes from an intrabronchial perspective using a virtual bronchoscopic navigation system, to assist with training in conventional transbronchial needle aspiration.

Incidence of airway complications in patients using endotracheal tubes with continuous aspiration of subglottic secretions

BACKGROUND

Continuous aspiration of subglottic secretions is effective in preventing ventilator-associated pneumonia, but it involves a risk of mucosal damage. The main objective of our study was to determine the incidence of airway complications related to continuous aspiration of subglottic secretions.

METHODS

In consecutive adult patients with continuous aspiration of subglottic secretions, we prospectively recorded clinical airway complications during the period after extubation. A multidetector computed tomography of the neck was performed during the period of 5 days following extubation to classify subglottic and tracheal lesions as mucosal thickening, cartilage thickening or deep ulceration.

RESULTS

In the 86 patients included in the study, 6 (6.9%) had transient dyspnea, 7 (8.1%) had upper airway obstruction and 18 (20.9%) had dysphonia at extubation. Univariate analysis identified more attempts required for intubation (2.3 ± 1.1 vs. 1.2 ± 0.5; p = 0.001), difficult intubation (71.4 vs. 10.1%, p = 0.001) and Cormack score III-IV (71.4 vs. 8.8%; p < 0.001) as risk factors for having an upper airway obstruction at extubation. The incidence of failed extubation among patients after planned extubation was 18.9% and 11 patients (12.7%) required tracheostomy. A multidetector computed tomography was performed in 37 patients following extubation, and injuries were observed in 9 patients (24.3%) and classified as tracheal injuries in 2 patients (1 cartilage thickening and 1 mild stenosis with cartilage thickening) and as subglottic mucosal thickenings in 7 patients.

CONCLUSIONS

The incidence of upper airway obstruction after extubation in patients with continuous aspiration of subglottic secretions was 8.1%, and the injuries observed by computed tomography were not severe and located mostly in subglottic space.

A comparison of virtual bronchoscopy versus flexible bronchoscopy in the diagnosis of tracheobronchomalacia in children

INTRODUCTION

Flexible bronchoscopy (FB) is the current gold standard for diagnosing tracheobronchomalacia. However, it is not always feasible and virtual bronchoscopy (VB), acquired from chest multi-detector CT (MDCT) scan is an alternative diagnostic tool. We determined the sensitivity, specificity, and positive and negative predictive values of VB compared to FB in diagnosing tracheobronchomalacia.

METHODS

Children aged <18-years scheduled for FB and MDCT were recruited. FB and MDCT were undertaken within 30-min to 7-days of each other. Tracheobronchomalacia (mild, moderate, severe, very severe) diagnosed on FB were independently scored by two pediatric pulmonologists; VB was independently scored by two pairs (each pair = pediatric pulmonologist and radiologist), in a blinded manner.

RESULTS

In 53 children (median age = 2.5 years, range 0.8-14.3) evaluated for airway abnormalities, tracheomalacia was detected in 37 (70%) children at FB. Of these, VB detected tracheomalacia in 20 children, with a sensitivity of 54.1% (95%CI 37.1-70.2), specificity = 87.5% (95%CI 60.4-97.8), and positive predictive value = 90.9% (95%CI 69.4-98.4). The agreement between pediatric pulmonologists for diagnosing tracheomalacia by FB was excellent, weighted κ = 0.8 (95%CI 0.64-0.97); but only fair between the pairs of pediatric pulmonologists/radiologists for VB, weighted κ = 0.47 (95%CI 0.23-0.71). There were 42 cases of bronchomalacia detected on FB. VB had a sensitivity = 45.2% (95%CI 30.2-61.2), specificity = 95.5% (95%CI 94.2-96.5), and positive predictive value = 23.2 (95%CI 14.9-34.0) compared to FB in detecting bronchomalacia.

CONCLUSION

VB cannot replace FB as the gold standard for detecting tracheobronchomalacia in children. However, VB could be considered as an alternative diagnostic modality in children with symptoms suggestive of tracheobronchomalacia where FB is unavailable. Pediatr Pulmonol. 2017;52:480-486. © 2016 Wiley Periodicals, Inc.

Computed Tomography Virtual Bronchoscopy: Normal Variants, Pitfalls, and Spectrum of Common and Rare Pathology

A broad spectrum of pathologies that involve the laryngotracheobronchial airway and imaging plays a crucial role in evaluating these abnormalities. Computed tomography with virtual bronchoscopy has been found to be very helpful in defining the location, extent, and nature of these lesions, and is increasingly being used even in patients with contraindications for fiberoptic bronchoscopy and laryngoscopy. Ionizing radiation, associated with virtual bronchoscopy, can be minimized by using low-dose multidetector computed tomography and hybrid iterative reconstruction techniques. Furthermore, retrospectively generated virtual bronchoscopy from a routinely acquired computed tomography data set eliminates additional cost and radiation. In the future, virtual bronchoscopy assisted with advanced navigational techniques will broaden the diagnostic and therapeutic landscape. This article presents the characteristic features of common and rare laryngotracheobronchial pathologies seen with virtual bronchoscopy.

Surgical treatment of non-malignant laryngotracheal stenosis

The objectives of this study were the following: (1) to analyze the results of surgical treatment of non-malignant subglottic laryngeal and tracheal stenosis, (2) to evaluate the feasibility and technical aspects of the video mediastinoscopy for the mobilization of the mediastinal trachea, (3) to evaluate the influence of the early internal condition of the anastomosis on the development of restenosis. From 1996 up to 2013, 75 patients aged 11-78 years underwent surgery for post-intubation/tracheostomy (71 patients), post-traumatic (3 patients), and idiopathic (1 patient) subglottic laryngeal and tracheal stenosis. Twenty-three (30.7 %) patients with subglottic laryngeal and upper tracheal stenosis underwent cricotracheal resection and thyrotracheal anastomosis (group A), while 52 (69.3 %) patients with tracheal stenosis underwent tracheal resection and cricotracheal or tracheotracheal anastomosis (group B). The length of the resected segment in patients of groups A and B was 28-55 (42 ± 11) mm and 18-65 (36 ± 14) mm, respectively, (p = 0.22). Perioperative complications within 30 days occurred in eight (34.8 %) patients of group A, and in six (11.5 %) patients of group B (p = 0.04). There was one intraoperative and one postoperative death on the third day due to heart failure. The excellent results were achieved in 63 (86.3 %), satisfactory in 8 (11.0 %), and unsatisfactory in 2 (2.7 %) patients. The incidence rate of perioperative complications is related to the location of the stenosis and the type of the resection and anastomosis. Video mediastinoscopy simplifies the mobilization of the mediastinal trachea, which allows for carrying out the anastomosis with minimal tension. Early internal abnormalities of the anastomosis predict its restenosis.

Comparison of virtual bronchoscopy with fiberoptic bronchoscopy findings in patients exposed to sulfur mustard gas

BACKGROUND

Fiberoptic bronchoscopy (FB) is the best modality for evaluation of tracheobronchial endoluminal lesions. Virtual bronchoscopy (VB) with the aid of computed tomography (CT) makes it possible to reconstruct endoscopic-like visualization of major airways. Sulfur mustard (SM) used during the Iraq-Iran war affects respiratory tracts and can lead to tracheobronchial stenosis.

PURPOSE

To compare VB with FB in SM-exposed patients suspected for airway stenosis.

MATERIAL AND METHODS

Thirty-one patients were evaluated with CT and bronchoscopic studies about 15 years after chemical attacks. The median age of patients was 40 years. Spiral CT scans were obtained and data were transferred to a workstation to generate VB images of major airways. Less than one week after CT scan, FB was performed.

RESULTS

For the tracheal pathologies seen in FB, the sensitivity, specificity, and accuracy of VB was 90.9%, 95%, and 93.5% for tracheal stenosis, 40%, 96.2%, and 87.1% for vocal cord problems, 100%, 100%, and 100% for postoperative changes, and 100%, 96.7%, and 96.8% for intratracheal nodule. The inflammation of mucosal surface could not be assessed by VB. The bronchial pathologies seen in FB included eight cases of stenosis, and one case of nodule. Sensitivity, specificity, and accuracy of VB for detection of bronchial stenosis was 62.5%, 97.8% and 92.6%, respectively. Overall sensitivity, specificity and accuracy of VB in detecting tracheobronchial stenosis were 78.9%, 97.0%, and 92.9%, respectively.

CONCLUSION

Our study indicates that VB is an accurate method for evaluating stenoses, endoluminal nodules, and poststenotic areas within the tracheobronchial tree of SM-exposed victims. This complementary method could be helpful in revealing hidden post-stenotic lesions and also better depict the long tracheal strictures and their actual length.

Evaluation of tracheal stenosis: comparison between computed tomography virtual tracheobronchoscopy with multiplanar reformatting, flexible tracheofiberoscopy and intra-operative findings

The aim of the study was to evaluate and compare various helical CT display modes [virtual endoscopy (VE)] and multiplanar reformations (MPR), conventional flexible tracheobronchoscopy (FT) and intra-operative (IO) findings in patients with tracheal stenosis and to analyze the advantage of MPR and VE in diagnosis and treatment planning and in postoperative follow-up. Thirty-seven patients with tracheal stenosis underwent standard neck and chest CT followed by MPR and VE. Results were correlated with the results of FT and IO findings. Thirty-three of the 37 stenoses were correctly graded and measured adequately using VE. Complete correlation among CT, fiberoptic tracheoscopy, and surgery of stenosis grading, stenosis length and length of planned resection segment of the trachea was noted between 33 of 37 patients with tracheal stenosis. Correlation between VE and IO was noted in 35 of 37 patients and between FT and VE was noted in 33 of 37 patients with tracheal stenosis. The sensitivity of VE was 94–97%, specificity was 100% with comparison to IO findings. The sensitivity and accuracy of MPR was 86–89% and specificity was 100% with comparison to FT findings. The results of the study indicate that VE is an excellent, consistent, and objective technique. VE with MPR is very useful in diagnostic evaluation and treatment planning in patients with tracheal stenosis.

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.

Managing obstruction of the central airways

Lung cancer is the most common cause of cancer death in Australia, Europe and the USA. Up to 20-30% of these cancers eventually affect the central airways and result in reduced quality of life, dyspnoea, haemoptysis, post-obstructive pneumonia and ultimately death. Non-malignant processes may also lead to central airway obstruction and can have similar symptoms. With the development of newer technologies, the last 20 years have seen the emergence of the field of interventional pulmonology to deal specifically with the diagnosis and management of thoracic malignancy, including obstruction of the central airways. This review discusses the pathology, pre-procedure work-up and management options for obstructing central airway lesions. Several treatment modalities exist for dealing with endobronchial pathology with local availability and expertise guiding choice of treatment. While the literature lacks large, multicentre, randomized studies defining the optimal management strategy for a given problem, there is growing evidence from numerous case studies of improved physiology, of quality of life and possibly of survival with modern interventional techniques.

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.

Advanced visualization of airways with 64-MDCT: 3D mapping and virtual bronchoscopy

OBJECTIVE

The purpose of this pictorial essay is to review the current role of virtual bronchoscopy and 3D imaging of the airways in clinical practice.

CONCLUSIONS

Virtual bronchoscopy produces high-resolution images of the tracheobronchial tree and endobronchial views that simulate the findings at conventional bronchoscopy. Interest in virtual bronchoscopy is increasing as a result of improvements in computer hardware and software and advances in MDCT that allow acquisition of isotropic data.

The current state of congenital tracheal stenosis

Congenital tracheal stenosis (CTS) is an uncommon condition that has challenged pediatric surgeons for decades. Patients with CTS can present with a wide spectrum of symptoms and varying degrees of severity. In addition, a variety of techniques have been devised to repair this malformation. A review of these procedures and our suggestions for clinical standards and practice guidelines will be presented in this paper. A retrospective review of the literature on CTS from 1964 to 31 March, 2006. There is not one standard technique for the repair of CTS, as individualized approach to each patient and airway lesion is necessary to optimize patient management; nevertheless there is a consensus about segmental resection and anastomosis being best for short segment stenosis while slide tracheoplasty is most effective for the long-segment ones. Conservative management is also an option for select group of patients with careful and close follow up. Survival following surgery over the years has improved, but mortality remained high, particularly in a specific subset of patients presenting at the age less than 1 month with associated cardiac malformations. In conclusion, CTS remains a significant challenge for pediatric surgeons. Additional research is required to improve our understanding of the pathogenesis of CTS, and to develop evidence-based treatment protocols for the entire spectrum of presentation including conservative management.

MDCT of the central airways: comparison with bronchoscopy in the evaluation of complications of endotracheal and tracheostomy tubes

OBJECTIVE

To evaluate the accuracy of multidetector row computed tomography (MDCT) compared with bronchoscopy in the assessment of airway complications related to endotracheal and tracheostomy tubes.

MATERIALS AND METHODS

A review was performed of all consecutive patients undergoing computed tomography (CT) and bronchoscopy for symptomatic complications of endotracheal or tracheostomy tubes during an 18-month period. MDCT imaging was performed according to a standard protocol and interpreted by an experienced thoracic radiologist before bronchoscopy. After bronchoscopy by an experienced interventional pulmonologist, CT and bronchoscopic findings were reviewed jointly, and the accuracy of CT was determined using bronchoscopy as the "gold standard."

RESULTS

The study population was comprised of 32 patients (range: 26 to 88 y, mean 55.6) with a total of 47 airway complications: tracheal stenosis (n=25), tracheomalacia (n=8), tracheal granulation tissue (n=8), tracheal cartilage fracture (n=4), tracheal perforation (n=1), and tracheostomy tube disruption (n=1). CT accurately diagnosed 42 of 47 airway complications (sensitivity 89.4%, specificity 95.2%, positive predictive value 85.7%, negative predictive value 96.5%). False negative findings at CT occurred in 5 (11.1%) of 47 cases. Contributing technical factors were identified in 3 (60.0%) of 5 false-negative cases, including the presence of tracheostomy tube during imaging and patient inability to complete the CT protocol.

CONCLUSIONS

MDCT of the central airways is highly accurate for detecting symptomatic airway complications of endotracheal and tracheostomy tubes, particularly when technical limitations to the performance of CT are minimized.

Multidetector row CT for imaging the paediatric tracheobronchial tree

The introduction of multidetector row computed tomography (MDCT) scanners has altered the approach to imaging the paediatric thorax. In an environment where the rapid acquisition of CT data allows general hospitals to image children instead of referring them to specialist paediatric centres, it is vital that general radiologists have access to protocols appropriate for paediatric applications. Thus a dramatic reduction in the delivered radiation dose is ensured with optimal contrast bolus delivery and timing, and inappropriate repetition of the scans is avoided. This article focuses on the main principles of volumetric CT imaging that apply generically to all MDCT scanners. We describe the reconstruction techniques for imaging the paediatric thorax and the low-dose protocols used in our institution on a 16-slice detector CT scanner. Examples of the commonest clinical applications are also given.

Tumoral and non-tumoral trachea stenoses: evaluation with three-dimensional CT and virtual bronchoscopy

BACKGROUND

We evaluated the ability of 3D-CT and virtual bronchoscopy to estimate trachea stenosis in comparison to conventional axial CT and fiberoptic bronchoscopy, with a view to assist thoracic surgeons in depicting the anatomical characteristics of tracheal strictures.

METHODS

Spiral CT was performed in 16 patients with suspected tracheal stenoses and in 5 normal subjects. Tracheal stenoses due to an endoluminal neoplasm were detected in 13 patients, whilst post-intubation tracheal stricture was observed in the other 3 patients. Multiplanar reformatting (MPR), volume rendering techniques (VRT) and virtual endoscopy (VE) for trachea evaluation were applied and findings were compared to axial CT and fiberoptic bronchoscopy. The accuracy of the procedure in describing the localization and degree of stenosis was tested by two radiologists in a blinded controlled trial.

RESULTS

The imaging modalities tested showed the same stenoses as the ones detected by flexible bronchoscopy and achieved accurate and non-invasive morphological characterization of the strictures, as well as additional information about the extraluminal extent of the disease. No statistically significant difference was observed between the bronchoscopic findings and the results of axial CT estimations (P = 1.0). No statistically significant differences were observed between bronchoscopic findings and the MPR, VRT and VE image evaluations (P = 0.705, 0.414 and 0.414 respectively).

CONCLUSION

CT and computed generated images may provide a high fidelity, noninvasive and reproducible evaluation of the trachea compared to bronchoscopy. They may play a role in assessment of airway patency distal to high-grade stenoses, and represent a reliable alternative method for patients not amenable to conventional bronchoscopy.

Surgical technique affects the risk for tracheostoma-related complications in post-ICU patients

CONCLUSIONS

This study provides evidence that the surgical technique used for tracheotomy influences the risk of tracheostomy-related complications. techniques resulting in an epithelialized tracheostoma seem to minimize the risk.

OBJECTIVE

Tracheotomies are frequently performed procedures in critically ill patients requiring long-term ventilation. Hence, we undertook a study to evaluate factors for tracheostomy-related complications among patients with a persisting stoma after critical care.

PATIENTS AND METHODS

The patients underwent endoscopic examination of the tracheostoma, larynx, and trachea. The intensive care units (ICUs) were contacted with a questionnaire about the patient's diagnosis, the indication for the tracheotomy, the date of the tracheotomy, and the method of the tracheotomy procedure.

RESULTS

A total of 170 patients were included in this study. In all, 57.6% of the patients had unstable tracheostomas, a stenosis of the tracheal lumen above the stoma was encountered in 48.2% (G I, <50% of the lumen = 27.6% and G II, >50% of the lumen = 20.6%), and below the stoma in 3.5% of the patients. A significant association was found between severe suprastomal stenosis, tracheostoma instability and the use of dilatational tracheotomy (DT) (p<0.001). A malacia of the trachea was significantly more common among female patients (p < 0.010).

Suprastomal tracheal stenosis after dilational and surgical tracheostomy in critically ill patients

We have previously reported cases of severe suprastomal stenosis after tracheostomy. In this observational study we investigated the occurrence of suprastomal stenosis as a late complication. Patients with persistent tracheostomy after intensive care underwent an endoscopic examination of tracheostoma, larynx and trachea. A percutaneous dilational tracheostomy was employed in 105 (71.9%) and surgical tracheostomy in 41 (28.1%) of the cases (n = 146). The incidence of severe suprastomal stenosis (grade II > 50% of the lumen) was 23.8% (25 of 105) after dilational tracheostomy and 7.3% (3 of 41) after surgical tracheostomy (p = 0.033). Age, gender, underlying disease, ventilation time, and swallowing ability were not significantly associated with the tracheal pathology. This study suggests that dilational tracheostomy is associated with an increased risk of severe suprastomal tracheal stenosis compared to the surgical technique.

Do technical parameters affect the diagnostic accuracy of virtual bronchoscopy in patients with suspected airways stenosis?

PURPOSE

Virtual bronchoscopy has gained popularity over the past decade as an alternative investigation to conventional bronchoscopy in the diagnosis, grading and monitoring of airway disease. The effect of technical parameters on diagnostic outcome from virtual bronchoscopy has not been determined. This meta-analysis aims to estimate accuracy of virtual compared to conventional bronchoscopy in patients with suspected airway stenosis, and evaluate the influence of technical parameters.

MATERIALS AND METHODS

A MEDLINE search was used to identify relevant published studies. The primary endpoint was the "correct diagnosis" of stenotic lesions on virtual compared to conventional bronchoscopy. Secondary endpoints included the effects of the technical parameters (pitch, collimation, reconstruction interval, rendering method, and scanner type), and date of publication on the diagnostic accuracy of virtual bronchoscopy.

RESULTS

Thirteen studies containing 454 patients were identified. Meta-analysis showed good overall diagnostic performance with 85% calculated pooled sensitivity (95% CI 77-91%), 87% specificity (95% CI 81-92%) and area under the curve (AUC) of 0.947. Subgroups included collimation of 3mm or more (AUC 0.948), pitch of 1 (AUC 0.955), surface rendering technique (AUC 0.935), and reconstruction interval of more than 1.25 mm (AUC 0.914). There was no significant difference in accuracy accounting for publication date, scanner type or any of the above variables. Weighted regression analysis confirmed none of these variables could significantly account for study heterogeneity.

CONCLUSION

Virtual bronchoscopy performs well in the investigation of patients with suspected airway stenosis. Overall sensitivity and specificity and diagnostic odds ratio for diagnosis of airway stenosis were high. The effects of pitch, collimation, reconstruction interval, rendering technique, scanner type, and publication date on diagnostic accuracy were not significant.

Transbronchial biopsy using endobronchial ultrasonography with a guide sheath and virtual bronchoscopic navigation

STUDY OBJECTIVES

We evaluated the feasibility, safety, and efficacy of transbronchial biopsy (TBB) using endobronchial ultrasonography with a guide sheath (EBUS-GS) and virtual bronchoscopy (VB) navigation for small peripheral pulmonary lesions < or = 30 mm in diameter.

DESIGN

Pilot study.

SETTING

A national university hospital.

PATIENTS

We performed TBB using EBUS-GS with VB navigation for 29 patients with 30 small peripheral pulmonary lesions (average diameter, 18.6 mm) between January 1, 2004, and August 31, 2004.

INTERVENTIONS

VB images were reconstructed from helical CT data. TBB was then performed using EBUS-GS with VB navigation.

RESULTS

In all patients, TBB was performed safely with no complications. Bronchi seen on VB imaging were highly consistent with the actual structures confirmed using fiberoptic bronchoscopy. Following VB navigation, the endobronchial ultrasonography (EBUS) probe was inserted into third- to sixth-generation bronchi. Twenty-four lesions (80%) were visualized on EBUS images. Average durations of the initial EBUS examination of lesions, first biopsy, and the total procedure were 9.56 min, 11.99 min, and 25.72 min, respectively. Nineteen lesions (63.3%) were diagnosed from histopathologic or cytologic examination. Diagnostic sensitivities were 44.4% (8 of 18) for lesions < 20 mm in mean diameter and 91.7% (11 of 12) for lesions 20 to 30 mm in mean diameter.

CONCLUSIONS

In summary, TBB using EBUS-GS with VB navigation was safely performed and was effective in diagnosing small peripheral pulmonary lesions.

[Endoscopic treatment of central airway stenosis: five years' experience]

OBJECTIVE

To describe our experience with interventional bronchoscopy in the treatment of central airway stenosis.

PATIENTS AND METHODS

We reviewed patient records and bronchoscopic findings. Clinical data, findings from computed tomography, techniques performed, complications, and results were recorded.

RESULTS

One-hundred and thirty-six patients (90 males and 46 females) were treated. The mean (SD) age was 57 (7) years (range, 3-81). A total of 320 therapeutic interventions were performed: 145 laser treatments, 33 balloon or mechanical dilatations, 26 electrocauterizations, and 116 stent insertions. Pathogenesis varied: in 64 (47%) patients, the stenosis was caused by a tumor (48 were bronchopulmonary and 16 nonpulmonary); in 72 (53%) patients, stenosis was secondary to a nontumor-related process, of which the most common was prolonged intubation (42% of these cases). Central airway patency was achieved in 92% (59/64) of the tumor-related stenoses and 96% (69/72) of those unrelated to tumors. Improvement in dyspnea was observed in 96% of all patients. Two deaths (due to hemoptysis and to acute myocardial infarction) occurred in the first week, for a 1.4% mortality rate. The most common complications were stent migration (8%; 9/116 cases) and the formation of granulomas (9%; 11/116).

CONCLUSIONS

Interventional bronchoscopy is an effective technique to resolve life-threatening obstructions of the central airways. Dyspnea improves immediately and there is no significant morbidity or mortality.

Virtual Bronchoscopy: Accuracy and Usefulness—An Overview

Multidetector CT generated virtual bronchoscopy (VB) represents one of the most recent developments in three-dimensional (3D) visualization techniques which allows a 3D evaluation of the airways down to the sixth- to seventh-generation. In comparison with real bronchoscopy, VB has some advantages: it is a non-invasive procedure that can visualize areas inaccessible to the flexible bronchoscope. Virtual bronchoscopy is able to evaluate bronchial stenosis and obstruction caused by both endoluminal pathology (tumor, mucus, foreign bodies) and external compression (anatomical structures, tumor, lymph nodes), can be helpful in the preoperative planning of stent placement and can be used to evaluate surgical sutures after lung transplantations, lobectomy or pneumectomy. In children, in some indications, VB can replace fiber optical bronchoscopy (FB) when this technique is considered too invasive. Finally, VB can also be used to evaluate anatomical malformations and bronchial variants. Virtual bronchoscopy is accurate but its accuracy is not 100% because false-positives and false-negatives occur. Virtual bronchoscopy contributes to a better understanding of tracheo-bronchial pathology. Fiber optical bronchoscopy will, without doubt, remain the golden standard but it can be expected that in the near future, the technique of VB will find a place in the daily routine.

Virtual endoscopy of the tracheo-bronchial system: sub-millimeter collimation with the 16-row multidetector scanner

The purpose of this study was to evaluate the scope of sub-millimeter collimation reconstruction parameters using 16-row computer tomography and ECG triggering on image quality in virtual bronchoscopy. Thirty-two patients (5 women, 27 men, mean age 66.6+/-1.4) who had been admitted for coronary artery bypass graft surgery underwent CT examination of the thorax (Sensation 16, Siemens, Inc., Forchheim, Germany). All patients were examined with 16x0.75-mm collimation. Image reconstruction was performed for two groups. In group A ( n=32), slice thickness of 1.5 mm and an overlap of 0.75 mm were used. In group B ( n=32), slice thickness of 0.75 mm and an overlap of 0.4 mm were applied. Retrospective ECG triggering was performed in all patients. The maximum order of recognizable bronchi was determined in each data set. In addition to assessing the maximum order of bronchial bifurcation, bronchial diameter was determined in truly perpendicular sections in each patient. For every segment proximal to a bifurcation, image quality was subjectively graded as poor (grade 1), moderate (grade 2) or good (grade 3). The observers were asked to identify the minimum cardiac movement ECG-triggered image sets assuming that they would be of better quality than the maximum cardiac movement ECG-triggered image sets. The Mann-Whitney U-test and the Fisher's Exact Test were used for statistical evaluation. In group A, a mean of 4.8+/-0.2 bifurcations was ascertained vs. 6.5+/-0.3 bifurcations in group B [ P<0.0003]. For bronchial diameters in group A, a mean of 7.5+/-0.4 mm was determined vs. 4.6+/-0.4 mm in group B [ P<0.0001]. In group B, two independent radiologists observed a significant shift to better image quality in all segments evaluated [ P<0.006 to P<0.000001]. Motion artifacts were judged as being significantly reduced by minimum cardiac movement ECG-triggering in group B [observer 1: P=0.0007 (20/32); observer 2: P=0.008 (18/32)], but not in group A [observer 1: P=0.286 (13/32); observer 2: P=0.123 (16/32)]. Sub-millimeter collimation and minimum cardiac movement ECG-triggered data acquisition allow deeper penetration into the tracheo-bronchial system allowing visualization of the bronchial surface down to diameters below 5 mm in certain cases up to the eighth bifurcation. Along with an enhanced visualization as such, better image quality is acquired in all segments evaluated. Trade off between better image quality, of doubtful diagnostic consequence, and much higher irradiation dose must be made.