Spiral CT with multiplanar and three-dimensional reconstructions accurately predicts tracheobronchial pathology

Therapeutic and prophylactic effects of radiation therapy in the management of recurrent granulation tissue induced tracheal stenosis: a review on the role of Endobronchial brachytherapy and external beam radiation therapy

PURPOSE

Granulation tissue-induced tracheal stenosis (mainly secondary to intubation or lung transplantation) is one of the most common etiologies of benign airway obstructions. Recurrence rates after standard treatment options (surgical resection and/or endobronchial interventions) can inadvertently worsen the stricture through the stimulation of more granulation tissue generation (via increased fibroblast activity and roliferation). Low-dose radiotherapy could be a promising tool to prevent granulation tissue formation after surgery and/or endobronchial interventions regarding its established role in the treatment of keloids or hypertrophic scars, two benign diseases with similar a pathophysiology to tracheal stenosis. This study reviews case reports and small series that used endobronchial brachytherapy (EBBT) or external beam radiotherapy (EBRT) for the management of refractory granulation tissue-induced tracheal stenosis after surgery and/or endobronchial interventions.

METHODS AND MATERIALS

Case reports and series (published up to October 2022) that reported outcomes of patients with recurrent granulation tissue-induced tracheal stenosis (after surgery and/or endobronchial interventions) treated by EBBT or EBRT (in definitive or prophylactic settings) were eligible.

RESULTS

Sixteen studies (EBBT: nine studies including 69 patients, EBRT: seven studies including 32 patients) were reviewed. The pooled success rate across all studies was 74% and 97% for EBBT and EBRT, respectively.

CONCLUSIONS

Radiation therapy appears to be effective in the management of selected patients with recurrent/refractory tracheal stenosis. Response to this treatment is usually good, but further studies with a larger number of patients and long-term followup are necessary to determine the optimal technique, dose, and timing of radiation therapy, late complications, the durability of response, and criteria for patient selection.

Association between surgical tracheostomy and chronic tracheal stenosis: A retrospective, single-center study

Background

Tracheal stenosis is a major complication of tracheostomy. Accordingly, anesthesiologists tend to select a smaller endotracheal tube (ETT) than usual for patients with a prior tracheostomy history, regardless of the presence or absence of respiratory symptoms. However, it likely comes from our trial and error, not scientific evidence. Therefore, in this study, we retrospectively examined the association between traditional surgical tracheostomy and tracheal stenosis as assessed by transverse computed tomography (CT).

Methods

Patients who underwent surgery for head and neck cancer from January 2010 to December 2013, with a temporary tracheostomy closed within a couple of months, were included. Exclusion criteria were tracheostoma before surgery, permanent tracheostomy, or insufficient CT follow-up. Transverse CT slices were measured 2 cm above and below the tracheostomy site (0.5 cm/slice for a total of 9 slices). The minimum cross-sectional tracheal area and horizontal and vertical diameters in transverse CT slices were compared before (baseline: BL), 6 months (6M) and 12 months (12M) after tracheostomy. Tracheal stenosis was defined as a decrease in the minimum cross-sectional tracheal area compared to BL.

Results

Of 112 patients, 77 were included. The minimum tracheal area was significantly decreased at 6M and 12M compared to BL (BL: mean 285 [SD 68] mm², 6M: 267 [70] mm², P < 0.01 vs. BL, 12M: 269 [68] mm², P < 0.01 vs. BL), and the localization was predominantly at or above the tracheostomy site at 6M and 12M. Tracheal stenosis was identified in 55 patients at 6M and in 49 patients at 12M without any respiratory symptoms. With regard to horizontal and vertical diameter, only horizontal diameter was significantly decreased at 6M and 12M compared to BL (BL: 16.8 [2.4] mm, 6M: 15.4 [2.7] mm, P < 0.01 vs. BL, 12M: 15.6 [2.8] mm, P < 0.01 vs. BL).

Conclusion

Conventional surgical tracheostomy was associated with a decreased horizontal diameter of the trachea. It resulted in a decreased cross-sectional tracheal area in more than one-half of the patients; however, no patient complained of any respiratory symptoms. Therefore, even without respiratory symptoms, prior tracheostomy causes an increased risk of tracheal stenosis, and using a smaller ETT than usual could be reasonable.

Detection of cervical spine trauma: Are 3-dimensional reconstructed images as accurate as multiplanar computer tomography?

INTRODUCTION

This study was conducted to assess the diagnostic accuracy of three-dimensional computed tomography (3D-CT) in detection of cervical spine injuries in symptomatic post-trauma patients using multiplanar computed tomography (MP-CT) as reference standard.

APPROACH

This cross-sectional study was conducted at Aga Khan University from July 2016 to January 2017. Patients were included using a non-probability, consecutive sampling. MP-CT and 3D- CT images were obtained and evaluated by a senior radiologist to identify cervical spine injuries.

RESULTS

205 patients were included in the study. For fractures, 3D-CT images had sensitivity of 71%, specificity of 100%, positive predictive value (PPV) of 100%, negative predictive value (NPV) of 96.8% and diagnostic accuracy of 97%. For dislocations, 3D-CT reported sensitivity of 83.34%, specificity of 100%, positive predictive value of 100% and negative predictive value of 99.5% and diagnostic accuracy of 99.5%.

CONCLUSION

3D-CT has good diagnostic accuracy for injuries of the cervical spine but must be reviewed simultaneously with multiplanar CT images.

Interventional Therapies for Central Airways

Central airway obstruction (CAO) is a dangerous and increasingly common problem. CAO refers to lesions causing narrowing of the trachea or mainstem bronchi and is generally divided into malignant and nonmalignant categories. These 2 entities may be caused by a variety of thoracic and extrathoracic diseases. Imaging is critical during the initial assessment of CAO and may help thoracic physicians focus the differential diagnosis and plan the safest and most appropriate diagnostic and therapeutic interventions. However, direct visualization via flexible or rigid bronchoscopy is often necessary for diagnostic and treatment purposes. A large number of procedures can be performed through bronchoscopy, with the goal of relieving the obstruction and improving patency of the airway. Deciding which procedure to perform is based both upon the type of lesion and whether the lesion is due to a malignant or nonmalignant process. Possible interventions include mechanical debridement, laser therapy, argon plasma coagulation, electrocautery, brachytherapy, and stent placement. Immediate postoperative and follow-up imaging is crucial to monitor for immediate, subacute, and chronic complications as well as disease progression and recurrence.

Reporting of central airway obstruction on radiology reports and impact on bronchoscopic airway interventions and patient outcomes

BACKGROUND

Central airway obstruction (CAO) is a serious condition that affects patients with both benign and malignant diseases. Timely recognition of CAO is crucial for prompt intervention aimed at improving the symptoms and quality of life of these patients. The aim of this study is to evaluate the formal radiology reporting of CAO and its impact on patients' outcomes.

METHODS

The medical records of patients who underwent advanced therapeutic bronchoscopy for CAO from August 2013 to September 2014 were retrospectively reviewed. Three researchers each reviewed 14 of the 42 formal radiology reports that were performed at 16 different medical and radiology centers.Patient characteristics were reported as means, medians, and standard deviations for continuous variables, and as frequencies and relative frequencies for categorical variables.

RESULTS

Out of 42 patients who underwent advanced bronchoscopy for planned therapeutic intervention, only 30 had radiology and pulmonology concordance about the airway findings of CAO. This is an agreement rate of 71.4% [95% confidence interval (CI): 56.7-83.3%] or a disagreement rate of 28.6% (95% CI: 16.7-43.3%). The radiology reports did not mention 31% of CAO on CT scans. The median time from CT imaging to bronchoscopy was significantly longer in patients with CAO not reported by the radiologists (21 versus 10 days; p = 0.011). Most patients improved postoperatively with no significant difference between the two groups.

CONCLUSIONS

Findings of CAOs were not described in a significant proportion of radiology reports. This results in significant delay in bronchoscopic airway management.

The Wonderful World of the Windpipe: A Review of Central Airway Anatomy and Pathology

A variety of pathologic processes can involve the central airways. Abnormalities may either diffusely or focally involve the tracheal or mainstem bronchial walls. Diseases that diffusely involve the tracheal wall can be subclassified as sparing the membranous trachea or circumferentially involving the tracheal wall. Focal diseases of the trachea and mainstem bronchi include benign and malignant causes. Additionally, congenital and acquired morphologic abnormalities of the trachea will be reviewed.

About a submucosal tracheal tumor

The authors report the case of 46-year-old man with recurrent hemoptysis. Bronchoscopy revealed a submucosal tumor protruding into the tracheal lumen. Transbronchial biopsy failed to obtain a conclusive diagnosis; only surgery allowed complete resection of the tumor and confirmed the diagnosis of tracheal mucoepidermoid carcinoma. We discuss the unusual submucosal presentation of this tumor, and the contribution of surgery for diagnosis and therapy.

Anesthesia for tracheal resection and reconstruction

Tracheal resection and reconstruction (TRR) is the treatment of choice for most patients with tracheal stenosis or tracheal tumors. Anesthesia for TRR offers distinct challenges, especially for the less experienced practitioner. This article explores the preoperative assessment, strategies for induction and emergence from anesthesia, the essential coordination between the surgical and anesthesia teams during airway excision and anastomosis, and postoperative care. The most common complications are reviewed. Targeted readership is practitioners with less extensive experience in managing airway surgery cases. As such, the article focuses first on the most common proximal tracheal resection. Final sections discuss specific considerations for more complicated cases.

Posttuberculosis tracheobronchial stenosis: use of CT to optimize the time of silicone stent removal

PURPOSE

To evaluate whether air pockets (tracheobronchial air columns in the space between the outer surface of the stent and the adjacent airway wall) discernible at computed tomography (CT) can help optimize the time of stent removal in patients with posttuberculosis tracheobronchial stenosis (PTTS).

MATERIALS AND METHODS

The study was approved by the institutional review board, and informed consent was obtained from all patients. Data from 41 patients (five men, 36 women) with a median age of 39 years (range, 21-64 years) who underwent silicone stent placement owing to PTTS, followed by CT and stent removal 6-12 months after clinical stabilization, were investigated retrospectively. Two radiologists determined whether the extent of air pockets on CT scans was associated with clinical success, which was defined as maintenance of a prosthesis-free airway for more than 2 years after stent removal. Radiologic features were compared for outcome by using a Wilcoxon two-sample test or Fisher exact test.

RESULTS

Stents were removed successfully in 31 patients (76%). Air pockets longer than 1 cm or longer than 2 cm were associated with successful stent removal (P = .04 and P = .006, respectively). The sensitivity and specificity of air pocket length in the prediction of successful stent removal were 84% and 50%, respectively, for air pockets longer than 1 cm and 68% and 70% for air pockets longer than 2 cm.

CONCLUSION

The extent of air pockets at chest CT shows correlation with the success of stent removal, indicates regression of stenosis, and may help guide the optimal time for stent removal.

Multidetector CT evaluation of central airways stenoses: Comparison of virtual bronchoscopy, minimal-intensity projection, and multiplanar reformatted images

Aims:

To evaluate the diagnostic utility of virtual bronchoscopy, multiplanar reformatted images, and minimal-intensity projection in assessing airway stenoses.

Settings and Design:

It was a prospective study involving 150 patients with symptoms of major airway disease.

Materials and Methods:

Fifty-six patients were selected for analysis based on the detection of major airway lesions on fiber-optic bronchoscopy (FB) or routine axial images. Comparisons were made between axial images, virtual bronchoscopy (VB), minimal-intensity projection (minIP), and multiplanar reformatted (MPR) images using FB as the gold standard. Lesions were evaluated in terms of degree of airway narrowing, distance from carina, length of the narrowed segment and visualization of airway distal to the lesion.

Results:

MPR images had the highest degree of agreement with FB (Κ = 0.76) in the depiction of degree of narrowing. minIP had the least degree of agreement with FB (Κ = 0.51) in this regard. The distal visualization was best on MPR images (84.2%), followed by axial images (80.7%), whereas FB could visualize the lesions only in 45.4% of the cases. VB had the best agreement with FB in assessing the segment length (Κ = 0.62). Overall there were no statistically significant differences in the measurement of the distance from the carina in the axial, minIP, and MPR images. MPR images had the highest overall degree of confidence, namely, 70.17% (n = 40).

Conclusion:

Three-dimensional reconstruction techniques were found to improve lesion evaluation compared with axial images alone. The technique of MPR images was the most useful for lesion evaluation and provided additional information useful for surgical and airway interventions in tracheobronchial stenosis. minIP was useful in the overall depiction of airway anatomy.

The feasibility of axial and coronal combined imaging using multi-detector row computed tomography for the diagnosis and treatment of a primary spontaneous pneumothorax

BACKGROUND

The preoperative detection of emphysema like changes (ELCs) is necessary for the successful treatment of pneumothorax. High resolution computed tomography (HRCT) has been used for the preoperative detection of ELCs. However, the traditional HRCT method uses only the axial view, which is perpendicular to the distribution of ELCs. This is not an ideal diagnostic method for the evaluation of ELCs.

METHODS

Forty-eight patients with pneumothorax had multi-detector computed tomography (MDCT) reconstruction using the coronal view. ELCs were evaluated in the axial and coronal view by a radiologist. A surgeon performed intra-operative examinations of the ELCs. The sensitivity of the different views was compared.

RESULTS

The detection sensitivity was 74.4% (70/94) for the axial view and 91.5% (86/94) for the axial-coronal combined view. The intra-operative detection rate was 95.7% (90/94). The preoperative detection of ELCs on the axial-coronal combined view was significantly higher than on the conventional axial view alone (p < 0.01).

CONCLUSIONS

Evaluation of ELCs on the axial and coronal combined HRCT improved the sensitivity of preoperative detection of ELCs compared to the conventional single axial HRCT. This increased sensitivity will help decrease the recurrence with VATS.

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.

Dynamic airway evaluation with volume CT: initial experience

PURPOSE

The purpose of the study was to prospectively establish the use of a novel multidetector computed tomography unit (MDCT) with 320 x 0.5 detector rows for the evaluation of tracheomalacia by using a dynamic expiratory low-dose technique.

METHODS

Six adult patients (5 men, 1 woman; mean age, 53.7 years [37-70 years]) referred for a clinical suspicion of tracheomalacia were studied on a 320-row MDCT unit by using the following parameters: 120 kVp, 40-50 mA, 0.5-second gantry rotation, and z-axis coverage of 160 mm sufficient to cover the thoracic trachea to the proximal bronchi. Image acquisition occurred during a forceful exhalation. The image data set was subject to the following analyses: cross-sectional area of airway lumen at 4 predefined locations (thoracic inlet, aortic arch, carina, and bronchus intermedius) and measurement of airway volume.

RESULTS

All 6 patients had evidence of tracheomalacia, the proximal trachea collapsed at a later phase of expiration (3-4 seconds) than the distal trachea (2-3 seconds). The most common region of airway collapse occurred at the level of the aortic arch (5/6 [83%]), Three patients (50%) had diffuse segmental luminal narrowing that involved the tracheobronchial tree. The radiation dose (estimated dose length product, computed tomography console) measured 293.9 mGy in 1 subject and 483.5 mGy in 5 patients.

CONCLUSIONS

Four-dimensional true isophasic and isovolumetric imaging of the central airways by using 320-row MDCT is a viable technique for the diagnosis of tracheomalacia; it provides a comprehensive assessment of airways dynamic.

MDCT of the airways: technique and normal results

The new generation of multidetector CT (MDCT) has revolutionized noninvasive imaging of proximal and distal airways. Exquisite anatomic details of the airway lumen and airway wall on axial CT images benefit in routine practice from postprocessing tools in adequate orientation. This method ensures an excellent assessment of the morphology and location of any pathology. It may be combined with use of very low dose CT. Airway lumen and airway wall areas may be quantitatively assessed on MDCT images by using specific techniques that are reproducible and accurate.

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 CT evaluation of airway metallic stents]

INTRODUCTION

Stenting is accepted in managing patients with inoperable obstruction of the upper airways. The choice of the type as well as the dimensions of stents are crucial as it impacts on the success of the procedure and potential complications which must be diagnosed non-invasively.

STATE OF THE ART

The goal of this review is to present our multidisciplinary experience using multidetector CT as a minimally invasive technique for detecting airway obstructions, for evaluating preoperatively local anatomic conditions useful to determinate the type and size of metallic stents to be used, and following non-invasively the stent in order to detect various complications.

CONCLUSIONS

MDCT acquisition should use thin slices as multiplanar reformations and 3D reconstructions play an essential complementary role to axial images in pre- and post-stent placement settings.

[Volume CT: recent advances in acquired abnormalities of the trachea]

OBJECTIVES

To show the recent improvements in CT imaging of the trachea due to the introduction of multidetector computed tomography (MDCT).

MATERIAL AND METHODS

MDCT technology, which was introduced in the early 00's, allows acquiring the entire airways within few seconds while using low dose parameters thanks to the natural high contrast of the airways.

RESULTS

Volume acquisition with isotropic voxels offers an excellent anatomical resolution in all directions, improving the quality of multiplanar reformations and 3D reconstructions, including virtual bronchoscopy. Therefore, the ability of CT for detecting and localizing tracheal abnormalities are improved, which is useful for planning endoscopy or open surgery, or assess their results. Dynamic acquisition during expiration is the last refinement permitted by MDCT, which is of value to detect tracheomalacia.

CONCLUSIONS

MDCT is a non-invasive technique to image the trachea. Its applications are numerous, such as depiction of anatomical or functional abnormalities, evaluation of local extent of the disease, planning and assessing open surgery or interventional endoscopy.

Preoperative assessment in patients with postintubation tracheal stenosis : Rigid and flexible bronchoscopy versus spiral CT scan with multiplanar reconstructions

BACKGROUND

Postintubation stenosis remains the most frequent indication for tracheal surgery. Rigid bronchoscopy has traditionally been considered the technique of choice for the preoperative diagnostic assessment. However, this technique is not routinely available, and new techniques such as flexible videobronchoscopy and spiral computed tomography (CT) scan with multiplanar reconstructions have been proposed as alternatives to rigid bronchoscopy. The aim of this study was to compare these techniques in the diagnostic assessment of patients with tracheal stenosis submitted to surgical treatment.

METHODS

Twelve patients who underwent airway resection and reconstruction for postintubation tracheal and laryngotracheal stenosis were preoperatively evaluated with rigid and flexible bronchoscopy and with spiral CT scan with multiplanar reconstructions. The following parameters were examined: involvement of subglottic larynx, length of the stenosis, and associated lesions. The results were compared with the intraoperative findings.

RESULTS

The accuracy of rigid bronchoscopy, flexible bronchoscopy, and CT scan in the evaluation of the involvement of subglottic larynx was, respectively, 92%, 83%, and 83%. The evaluation of the length of the stenosis was correct in 83%, 92%, and 25% of the patients, respectively, with rigid bronchoscopy, flexible bronchoscopy, and CT scan. A significant correlation was observed between the length of the stenosis measured intraoperatively and preoperatively with rigid (p < 0.001) and flexible bronchoscopy (p < 0.05) but not with CT scan (p = 0.08). The three techniques correctly showed the presence of an associated tracheoesophageal fistula in two patients, but CT scan did not correctly show the exact location of the fistula in relation to the airway. Flexible bronchoscopy was the only effective technique in the assessment of laryngeal function.

CONCLUSIONS

Rigid bronchoscopy remains the procedure of choice in the evaluation of candidates for tracheal resection and reconstruction for postintubation stenosis, and it should be available in centers that perform surgery of the airway. Flexible bronchoscopy and CT scan have to be considered complementary techniques in the evaluation of laryngeal function and during follow-up.

Multidetector CT of the central airways

Multidetector CT (MDCT) has revolutionized non-invasive imaging of the central airways. Compared to single-detector helical CT scans, MDCT results in higher spatial resolution, faster speed, greater anatomic coverage, and higher quality multiplanar reformation and 3-D reconstruction images. This article reviews recent advances in central airway imaging with MDCT. A special emphasis is placed upon the role of advanced reconstruction methods and functional imaging.

High resolution volume imaging of airways and lung parenchyma with multislice CT

The value of multislice CT (MSCT) in imaging the peripheral airways and lung parenchyma has not been widely investigated. In this article the authors' experience in the use of MSCT (4-slice scanner) in imaging patients with suspected parenchymal lung disease or airways abnormalities will be presented. The technique described should be modified with the more modern 8-slice or 16-slice scanners. The whole thorax is scanned contiguously using 4 x 1 mm collimation from the lung bases up to apices in end-inspiration while the patient is in the prone position. Collimation of 2 x 0.5 mm is used at 8-10 levels evenly spaced in expiratory scans and also in the breathless patient who is scanned during gentle breathing. High resolution images of the lungs (1 mm slice thickness) are reconstructed in the following planes: axial (10 mm apart from apices to bases), coronal (six evenly spaced through the chest) and sagittal (four images evenly spaced through each lung). Paddlewheel reconstruction is used if further assessment of the airways is required, and three-dimensional imaging is used mainly for assessment of the trachea and major bronchi. Contiguous axial images (10 mm slice thickness) of the whole lung and mediastinum are also produced and referred to as a screenogram. Axial images of 1 mm slice thickness are produced with expiratory scans and for breathless patients. All the images are produced independently by the radiographic staff and are provided as hard copies (20 frames/film) for reporting. However, if facilities are adequate, direct reporting from the workstation is more effective in reviewing large number of images. The technique is effective in assessment of infiltrative lung disease, emphysema, bronchiectasis and central airways. The screenogram offers comprehensive evaluation of the lung and mediastinum, but the radiation dose associated with high resolution volume imaging remains a source of concern.

Virtual bronchoscopy for evaluation of airway disease

The data presented above indicate that VB is a novel and extremely useful modality for airway evaluation in patients who have benign and malignant disease. VB is noninvasive, with no additional radiation exposure relative to standard CT scans of the chest. Commercial software allows for the interactivity of 2D and 3D images. The ability to examine 2D and 3D anatomic detail from multiple directions enables precise assessment of intraluminal and extraluminal pathology. The authors' experience indicates that VB is a superb modality for assessing the length of airway stenoses and ascertaining airway patency distal to these lesions (Fig. 6). As such, VB has proven to be extremely useful for determining the feasibility of endobronchial procedures such as dilations, stent placements, and laser ablation of endobronchial tumors. Ferretti et al [27] observed that VB is an excellent noninvasive means for long-term monitoring of tracheobronchial stents. Furthermore, the authors have found VB useful for guiding the bronchoscopic evaluation of patients who have intermittent hemoptysis secondary to lesions in peripheral airways. The 3D anatomic detail provided by VB has proven useful for assessing the feasibility of lung-sparing procedures in patients who have limited pulmonary reserve and for sequentially evaluating treatment response in patients who have inoperable disease. Currently, the main limitation of VB pertains to its inability to evaluate the mucosal surface of the respiratory tract reliably. Although form can be detected, mucosal color, irregularity, or friability cannot be assessed. As such, VB cannot be used for routine surveillance of patients at high risk of developing airway malignancies. The development of novel aerosolized contrast agents or spectroscopic techniques that can discriminate benign versus malignant mucosal tissues might enhance the sensitivity and specificity of VB for the detection of preinvasive cancers within the respiratory tract.

Central Airway Obstruction

Central airway obstruction is a problem facing all medical and surgical subspecialists caring for patients with chest diseases. The incidence of this disorder appears to be rising because of the epidemic of lung cancer; however, benign causes of central airway obstruction are being seen more frequently as well. The morbidity is significant and if left untreated, death from suffocation is a frequent outcome. Management of these patients is difficult, but therapeutic and diagnostic tools are now available that are beneficial to most patients and almost all airway obstruction can be relieved expeditiously. This review examines current approaches in the workup and treatment of patients suffering from airway impairment. Although large, randomized, comparative studies are not available, data show significant improvement in patient outcomes and quality of life with treatment of central airway obstruction. Clearly, more studies assessing the relative utility of specific airway interventions and their impact on morbidity and mortality are needed. Currently, the most comprehensive approach can be offered at centers with expertise in the management of complex airway disorders and availability of all endoscopic and surgical options.

Comparison of Axial High-Resolution CT and Thin-Section Multiplanar Reformation (MPR) for Diagnosis of Diseases of the Pulmonary Parenchyma

PURPOSE

We evaluated the diagnostic utility of coronal multiplanar reformation (MPR) images produced by multi-detector row CT in diffuse and focal pulmonary parenchymal disease.

MATERIALS AND METHODS

A phantom study was conducted comparing spatial and low-contrast resolutions of axial high-resolution CT (HRCT) and coronal MPR. Non-spiral axial HRCT was performed with 2-mm collimation, and spiral CT was performed with 1-mm collimation and 8:1 pitch, from which MPR images were produced at 1.9-mm thickness and 5-mm intervals. Forty-nine patients were included in the clinical study. Three reviewers independently assessed the lesion conspicuity and disease extent on both axial HRCT and coronal MPR images, and the diagnostic utility of the coronal images was evaluated. Two reviewers subsequently assessed axial and coronal images separately, and the extent of abnormalities shown by each was compared.

RESULTS

In phantom study, coronal MPR images were inferior to axial images but were considered adequate for clinical use. In clinical study, the image quality of MPR was regarded as good for observation of the lung parenchyma in all cases. The mean percentage of abnormalities for which 3 reviewers determined coronal MPR images as superior or additional information available was 22.1%, whereas 72.4% was regarded as comparable and 5.5% as inferior to axial images. Interobserver agreement was good (weighted kappa statistics 0.45-0.61). The extent of abnormality was judged to be shown equally on the axial and MPR images with good interobserver agreement (kappa statistics 0.63).

CONCLUSION

Coronal MPR images may have an additional role to axial HRCT images in the clinical interpretation of lung parenchymal abnormalities.

State-of-the-Art Imaging of the Central Airways

Recent technological advances in CT imaging have revolutionized non-invasive imaging of the central airways. It is now possible to image the entire central airways in a few seconds and to create elegant three-dimensional reconstructions of the airways in a few minutes. The fast speed of CT scanning now allows for a dynamic assessment of the central airways, expanding the ability to non-invasively detect functional abnormalities such as tracheobronchomalacia. The purpose of this article is to familiarize clinicians with recent advances in airway imaging. A special emphasis is placed upon advanced CT reconstruction methods and their potential contributions to the evaluation of a variety of airway disorders.

Acute complications of artificial airways

In conclusion, though there has been a dramatic reduction in the acute complications of artificial airways in the last hundred years, it remains crucial for the intensivist/anesthesiologist to have an implicit understanding of the anatomy and physiology of the process of ETI. As new techniques such as PDT are introduced, we must investigate their utility compared with the current standard of care in the most rigorous fashion. Additionally, as many of the complications of ETI can lead to increases in morbidity and mortality, prompt diagnosis and management are essential.

Multiplanar and three-dimensional imaging of the thorax

Although axial images are sufficient for diagnosis in most instances, knowledge of multiplanar imaging techniques is essential to apply them in appropriate circumstances. In particular, appropriately applied multiplanar imaging adds confidence to interpretations and assists surgeons and bronchoscopists in planning procedures. The need for multiplanar imaging must be assessed before performing any study so that the image acquisition parameters allow for suitable reformations.

Multislice helical CT of the central airways

Multislice helical CT has revolutionized the non-invasive evaluation of the central airways with CT. The quick speed of image acquisition afforded by MSCT improves the quality of end-inspiration images and has expanded the ability to assess the airway during dynamic exhalation. Furthermore, the improved quality of multiplanar and three-dimensional images provided by MSCT has ushered in an exciting era of alternative methods of viewing CT data that are more visually accessible and often more anatomically meaningful. At present, the author routinely obtains multiplanar reformation and three-dimensional images for assessment of a variety of central airway abnormalities, including airway stenoses and webs, complex airway diseases, extrinsic airway compression, tracheobronchomalacia, and poststent placement. Further advances in CT technology, data processing, and image display, and increased clinical experience with advanced imaging reconstruction methods, will likely further expand the role of multiplanar and three-dimensional reconstruction images in the assessment of a wide variety of central airways disorders in the near future.

Tracheobronchial stenting for tuberculous airway stenosis

We reviewed the results of the use of the Dumon silicone stents in patients experiencing tuberculous tracheobronchial stenosis since 1994, using a retrospective case review in a university teaching hospital with 1,450 beds serving a population of > 1.8 million. Between February 1994 and September 2001, seven patients with tuberculous tracheobronchial stenosis (mean age, 43 years) underwent a total of 11 dilatations with placement of 10 straight stents and 1 Y stent. Under general anesthesia, all patients underwent rigid bronchoscopy and dilatation of the stenosis with placement of a Dumon stent. There were no deaths. One patient developed a pneumothorax. Two patients experienced migration of the stent, which required reintervention for adjustment of position of the stent. The stents were left in situ for a mean period of 32 months. There was marked improvement in dyspnea in all patients after the procedure, as determined by visual analog scale. Endoscopic dilatation with placement of a silicone stent is an effective treatment for patients with tuberculous tracheobronchial stenosis.

CT virtual bronchoscopy of the central airways in patients with Wegener's granulomatosis

OBJECTIVES

To compare CT virtual bronchoscopy (VB) to CT alone and to conventional bronchoscopy for evaluation of central airway stenoses in patients with Wegener's granulomatosis.

DESIGN

Prospective observer study, in which 18 thin-section helical CT scans of the trachea and bronchi of 11 patients with Wegener's granulomatosis were obtained. VB was performed using surface rendering and was evaluated by one bronchoscopist and one radiologist in a blinded fashion. Bronchoscopic correlation within an average of 1.8 days of CT was available.

MEASUREMENTS AND RESULTS

VB displayed 188 of 198 bronchi (95%). Thirty-two of 40 stenoses (80%) were detected by VB by at least one of two physicians (double reading), and 22 of 40 stenoses (55%) were detected by a third physician reading only the CT.

CONCLUSIONS

VB depicts bronchi to the segmental level and detects the majority of central airway stenoses in patients with Wegener's granulomatosis. A team approach is useful to attain optimal clinical benefit from VB for these patients.

Successful treatment of mucoepidermoid carcinoma of the carina

We successfully treated a 33-year-old man with mucoepidermoid carcinoma at the carina. Through preoperative spiral computed tomography with multiplanar and three-dimensional reconstructions, the lesion extended along the right main bronchus across the orifice of the right upper lobe. He underwent a carinal resection plus right upper lobectomy and reconstruction of the carina. He shows neither anastomotic complication nor recurrence of disease 1 year after surgery. Spiral computed tomography was used to evaluate the preoperative and postoperative state of the central airway.

Incidence of tracheal stenosis and other late complications after percutaneous tracheostomy

OBJECTIVE

To determine the incidence of tracheal stenosis, voice and breathing changes, and stomal complications after percutaneous dilatational tracheostomy (PDT).

METHODS

From December 1992 through June 1999, 420 critically ill patients underwent 422 PDTs. There were 340 (81%) long-term survivors, 100 (29%) of whom were interviewed and offered further evaluation by fiberoptic laryngotracheoscopy (FOL) and tracheal computed tomography (CT). Tracheal stenosis was defined as more than 10% tracheal narrowing on transaxial sections or coronal and sagittal reconstruction views. Forty-eight patients agreed to CT evaluation; 38 patients also underwent FOL. CT and FOL evaluations occurred at 30 +/- 25 (mean +/- standard deviation) months after PDT.

RESULTS

Twenty-seven (27%) patients reported voice changes and 2 (2%) reported persistent severe hoarseness. Vocal cord abnormalities occurred in 4/38 (11%) patients, laryngeal granuloma in 1 (3%) patient, focal tracheal mucosal erythema in 2 (5%) patients, and severe tracheomalacia/stenosis in 1 (2.6%) patient. CT identified mild (11-25%) stenosis in 10 (21%) asymptomatic patients, moderate (26-50%) stenosis in 4 (8.3%) patients, 2 who were symptomatic, and severe (>50%) stenosis in 1 (2%) symptomatic patient. Ten patients (10%) reported persistent respiratory problems after tracheal decannulation, but only four agreed to be studied. Two patients had moderate stenosis, and one had severe stenosis. One patient's CT scan was normal. No long-term stomal complications were identified or reported.

CONCLUSIONS

Subjective voice changes and tracheal abnormalities are common after endotracheal intubation followed by PDT. Long-term follow-up of critically ill patients identified a 31% rate of more than 10% tracheal stenosis after PDT. Symptomatic stenosis manifested by subjective respiratory symptoms after decannulation was found in 3 of 48 (6%) patients.

Clinical applications of 2D and 3D CT imaging of the airways--a review

Hardware and software evolution has broadened the possibilities of 2D and 3D reformatting of spiral CT and MR data set. In the study of the thorax, intrinsic benefits of volumetric CT scanning and better quality of reconstructed images offer us the possibility to apply additional rendering techniques to everyday clinical practice. Considering the large number and redundancy of possible post-processing imaging techniques that we can apply to raw CT sections data, it is necessary to precisely set a well-defined number of clinical applications of each of them, by careful evaluation of their benefits and possible pitfalls in each clinical setting. In diagnostic evaluation of pathological processes affecting the airways, a huge number of thin sections is necessary for detailed appraisal and has to be evaluated, and information must then be transferred to referring clinicians. By additional rendering it is possible to make image evaluation and data transfer easier, faster, and more effective. In the study of central airways, additional rendering can be of interest for precise evaluation of the length, morphology, and degree of stenoses. It may help in depicting exactly the locoregional extent of central tumours by better display of relations with bronchovascular interfaces and can increase CT/bronchoscopy sinergy. It may allow closer radiotherapy planning and better depiction of air collections, and, finally, it could ease panoramic evaluation of the results of dynamic or functional studies, that are made possible by increased speed of spiral scanning. When applied to the evaluation of peripheral airways, as a completion to conventional HRCT scans, High-Resolution Volumetric CT, by projection slabs applied to target areas of interest, can better depict the profusion and extension of affected bronchial segments in bronchiectasis, influence the choice of different approaches for tissue sampling by better evaluation of the relations of lung nodules with the airways, or help to detect otherwise overlooked slight pathological findings. In the exploration of the air-spaces of the head and neck, targeted multiplanar study can now be performed without additional scanning by retro-reconstructed sections from original transverse CT slices. Additional rendering can help in surgical planning, by simulation of surgical approaches, and allows better integration with functional paranasal sinuses endoscopic surgery, by endoscopic perspective rendering. Whichever application we perform, the clinical value of 2D and 3D rendering techniques lies in the possibility of overcoming perceptual difficulties and 'slice pollution', by easing more efficient data transfer without loss of information. 3D imaging should not be considered, in the large majority of cases, as a diagnostic tool: looking at reformatted images may increase diagnostic accuracy in only very few cases, but an increase in diagnostic confidence could be not negligible. The purpose of the radiologist skilled in post-processing techniques should be that of modifying patient management, by more confident diagnostic evaluation, in a small number of patients, and, in a larger number of cases, by simplifying communication with referring physicians and surgeons. We will display in detail possible clinical applications of the different 2D and 3D imaging techniques, in the study of the tracheobronchial tree, larynx, nasal cavities and paranasal sinuses by Helical CT, review relating bibliography, and briefly discuss pitfalls and perspectives of CT rendering techniques for each field.

Evaluation of tracheobronchial diseases: comparison of different imaging techniques

OBJECTIVE

To compare the clinical utility of the different imaging techniques used for the evaluation of tracheobronchial diseases.

MATERIALS AND METHODS

Forty-one patients with tracheobronchial diseases [tuberculosis (n = 18), bronchogenic carcinoma (n = 10), congenital abnormality (n = 3), post-operative stenosis (n = 2), and others (n = 8)] underwent chest radiography and spiral CT. Two sets of scan data were obtained: one from routine thick-section axial images and the other from thin-section axial images. Multiplanar reconstruction (MPR) and shaded surface display (SSD) images were obtained from thin-section data. Applying a 5-point scale, two observers compared chest radiography, routine CT, thin-section spiral CT, MPR and SSD imaging with regard to the detection, localization, extent, and characterization of a lesion, information on its relationship with adjacent structures, and overall information.

RESULTS

SSD images were the most informative with regard to the detection (3.95+/-0.31), localization (3.95+/-0.22) and extent of a lesion (3.85+/-0.42), and overall information (3.83+/-0.44), while thin-section spiral CT scans provided most information regarding its relationship with adjacent structures (3.56+/-0.50) and characterization of the lesion (3.51+/-0.61).

CONCLUSION

SSD images and thin-section spiral CT scans can provide valuable information for the evaluation of tracheobronchial disease.

Surgical treatment of tracheal hamartoma

Tracheal hamartoma is a rare tumor and difficult to diagnose. A case is presented in which tracheal hamartoma was misdiagnosed and treated for four years as asthma. The tumor was curatively excised via posterolateral thoracotomy.

Surgical management of tracheal tumors

BACKGROUND

Resection of tracheal tumors is particularly challenging when the neoplasm involves the carina or is located in close proximity. We reviewed our experience with 22 tracheal resections for tumor.

METHODS

In this retrospective review, adenoid cystic carcinoma was diagnosed in 13 patients, squamous cell carcinoma in 5, typical carcinoid in 2, and leiomyoma and benign fibrous histiocytoma, in 1 each. There were 19 segmental resections with direct anastomosis, and 3 complex resections in which the carina was involved.

RESULTS

One patient with tumor in the trachea and left main bronchus underwent resection through simultaneous bilateral thoracotomy and died. During 2 to 17 years of follow-up, 2 patients died of unrelated disease, 2 died of metastases, and 1 is receiving radiotherapy for recurrence. Sixteen patients are well and free of tumor.

CONCLUSIONS

Complete resection of all neoplastic tissue is mandatory, but benign and low-grade malignant tumors should be resected conservatively with preservation of lung parenchyma. Options for treatment of neoplasms involving trachea and left bronchus should include resection of the neoplasm in two stages, thus minimizing trauma of each operation.