Multidetector CT evaluation of airway stents: what the radiologist should know

Multidetector computed tomography imaging planning for bronchoscopy stent and valve placement in the treatment of COPD, air leaks, and airway stenosis

Bronchoscopy using a flexible bronchoscope is considered a safe procedure and has been used for diagnosing and treating airway and parenchymal lung diseases. Bronchoscopic interventions in selected patients with emphysema, airway stenosis, and air leaks provide new treatment options. The application of multidetector computed tomography (MDCT) planning prior to bronchoscopy is comprehensively addressed. Using MDCT scan for pre-procedural planning, ensures precise navigation and device placement during bronchoscopy, ultimately improving patient outcomes. Radiological features can be correlated with bronchoscopy findings, linking MDCT images with direct bronchoscopy observations. This educational statement provides a comprehensive overview of the integration of computed tomography and bronchoscopy in managing different pulmonary conditions treated with endobronchial valve and airway stent placement, focusing on key aspects to enhance understanding and application in clinical practice. Emphasis is placed on their role in treating airway stenosis (AS), air leaks, and chronic obstructive pulmonary disease (COPD), highlighting the conditions under which these procedures are most beneficial. It explores how MDCT imaging contributes to the diagnosis and treatment planning of these conditions and the correct interpretation of MDCT image findings during follow-up after the procedure.

Chest Intensive Care Unit Imaging: Pearls and Pitfalls

Imaging plays a major role in the care of the intensive care unit (ICU) patients. An understanding of the monitoring devices is essential for the interpretation of imaging studies. An awareness of their expected locations aids in identifying complications in a timely manner. This review describes the imaging of ICU monitoring and support catheters, tubes, and pulmonary and cardiac devices, some more commonly encountered and others that have been introduced into clinical patient care more recently. Special focus will be placed on chest radiography and potential pitfalls encountered.

Imaging of therapeutic airway interventions in thoracic oncology

Tracheobronchial obstruction, haemoptysis, and airway fistulas caused by airway involvement by primary or metastatic malignancies may result in dyspnoea, wheezing, stridor, hypoxaemia, and obstructive atelectasis or pneumonia, and can lead to life-threatening respiratory failure if untreated. Complex minimally invasive endobronchial interventions are being used increasingly to treat cancer patients with tracheobronchial conditions with curative or, most often, palliative intent, to improve symptoms and quality of life. The selection of the appropriate treatment strategy depends on multiple factors, including tumour characteristics, whether the lesion is predominately endobronchial, shows extrinsic compression, or a combination of both, the patient's clinical status, the urgency of the clinical scenario, physician expertise, and availability of tools. Pre-procedure multidetector computed tomography (MDCT) imaging can aid in the most appropriate selection of bronchoscopic treatment. Follow-up imaging is invaluable for the early recognition and management of any potential complication. This article reviews the most commonly used endobronchial procedures in the oncological setting and illustrates the role of MDCT in planning, assisting, and follow-up of endobronchial therapeutic procedures.

CT findings of non-neoplastic central airways diseases

Non-neoplastic lesions of central airways are uncommon entities with different etiologies, with either focal or diffuse involvement of the tracheobronchial tree. Clinical symptoms of non-neoplastic tracheobronchial diseases are non-specific, and diagnosis is difficult, especially in the early stages. Three-dimensional computed tomography (3D-CT) is an evaluable tool as it allows to assess and characterize tracheobronchial wall lesions and meanwhile it enables the evaluation of airways surrounding structures. Multiplanar reconstructions (MPR), minimum intensity projections (MinIP), and 3D Volume Rendering (VR) (in particular, virtual bronchoscopy) also provide information on the site and of the length of airway alterations. This review will be discussed about (1) primary airway disorders, such as relapsing polychondritis, tracheobronchophathia osteochondroplastica, and tracheobronchomegaly, (2) airway diseases, related to granulomatosis with polyangiitis, Chron's disease, Behcet's disease, sarcoidosis, amyloidosis, infections, intubation and transplantation, (3) tracheobronchial malacia, and (4) acute tracheobronchial injury. 3D-CT findings, especially with MPR and 3D VR reconstructions, allows us to evaluate tracheobronchial disease morphologically in detail.

Customization of stent design for treating malignant airway stenosis with the aid of three-dimensional printing

Background

The treatment of malignant stenosis involving the carina or bronchi is challenging due to complicated anatomy with individual variation, which makes it necessary to customize stents for each patient. Therefore, this study aims to evaluate the feasibility of a novel metallic segmented airway stent customized with the aid of three-dimensional (3D) printing for such cases.

Methods

The stents were individually customized with the aid of a 3D printed mold based on computed tomography (CT) images according to the anatomical features of the airway. A segmented design was applied on the junction part of the main stem and the branches to fit the dynamic changes of the carina angle. In 12 patients with airway stenosis caused by malignancies including esophageal cancer (EC) and lung cancer (LC), the stents were implanted. The technical and clinical success of the stenting procedure, Hugh-Jones (HJ) classification, Karnofsky performance status (KPS), and stent-related complications of patients were evaluated.

Results

The stenting procedure was technically successful in all patients, and 11 patients showed significant palliation of dyspnea after stenting. The HJ and KPS classification of patients after stent insertion improved significantly compared with those before stenting (P=0.003 and P=0.006, respectively). During follow-up, granulation tissue proliferation and sputum retention were found in two and four patients, respectively.

Conclusions

This study shows that the implantation of a novel stent designed with the aid of 3D printing is feasible for relieving dyspnea and improving performance status of patients with inoperable malignant stenosis involving the carina or bronchi.

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.

Quantified evaluation of tracheal compression in pediatric complex congenital vascular ring by computed tomography

Clinically, early diagnosis and treatment is important for survival of pediatric with vascular ring (VR) associated with congenital heart disease (CHD), and accurate evaluation of VR is a prerequisite for repair surgical. The study aimed to assess the quantitative characteristics of tracheal compression in pediatrics with VR and CHD using dual-source computed tomography (DSCT), and further provided effective information for surgical decisions. A total of 49 VR patients with CHD and 56 controls were enrolled. The tracheal quantitative measurements (short diameter, long diameter, tracheal area and tracheal length) were obtained, and the degree of tracheal compression was assessed. Our results indicated that VR associated with CHD may cause more serious and complex symptoms, and the greater tracheal compression were found on DSCT when more severe symptoms were present (r = 0.84). The degree of tracheal compression was significantly different within the VR group between those with and without surgery (P = 0.002). Finally, there were good agreement among (1-long diameter ratio), (1-short diameter ratio) and (1-area ratio) in patients and controls, respectively. This study indicated that DSCT enables provides accurate quantitative tracheal compression information for VR pediatrics associated with CHD, and evaluation of the degree of tracheal compression by 1-area ratio may contribute to the repair surgical of VR.

Evaluating the interaction of a tracheobronchial stent in an ovine in-vivo model

Tracheobronchial stents are used to restore patency to stenosed airways. However, these devices are associated with many complications such as stent migration, granulation tissue formation, mucous plugging and stent strut fracture. Of these, granulation tissue formation is the complication that most frequently requires costly secondary interventions. In this study a biomechanical lung modelling framework recently developed by the authors to capture the lung in-vivo stress state under physiological loading is employed in conjunction with ovine pre-clinical stenting results and device experimental data to evaluate the effect of stent interaction on granulation tissue formation. Stenting is simulated using a validated model of a prototype covered laser-cut tracheobronchial stent in a semi-specific biomechanical lung model, and physiological loading is performed. Two computational methods are then used to predict possible granulation tissue formation: the standard method which utilises the increase in maximum principal stress change, and a newly proposed method which compares the change in contact pressure over a respiratory cycle. These computational predictions of granulation tissue formation are then compared to pre-clinical stenting observations after a 6-week implantation period. Experimental results of the pre-clinical stent implantation showed signs of granulation tissue formation both proximally and distally, with a greater proximal reaction. The standard method failed to show a correlation with the experimental results. However, the contact change method showed an apparent correlation with granulation tissue formation. These results suggest that this new method could be used as a tool to improve future device designs.

Chest CT with iterative reconstruction algorithms for airway stent evaluation in patients with malignant obstructive tracheobronchial diseases

The aim of the study was to investigate the image quality of low-dose CT images with different reconstruction algorithms including filtered back projection (FBP), hybrid iterative reconstruction (HIR), and iterative model reconstruction (IMR) algorithms by comparison of routine dose images with FBP reconstruction, in patients with malignant obstructive tracheobronchial diseases.In total, 60 patients (59 ± 9.3 years, 37 males) with airway stent who are randomly assigned into 2 groups (routine-dose [RD] and low-dose [LD] group, 30 for each) underwent chest CT on a 256-slice CT (RD-group 120 kV, 250 mAs, LD-group 120 kV, 120 mAs). Images were reconstructed with filtered back projection (FBP) algorithm in the RD group, whereas with FBP, HIR and IMR algorithms in the LD group. Effective radiation dose of both groups was recorded. Image-quality assessment was performed by 2 radiologists according to structure demarcation near stents, artifacts, noise, and diagnostic confidence using a 5-point scale (1 [poor] to 5 [excellent]). Image noise and CNR were measured.The effective radiation dose of LD group was reduced 52.7% compared with the RD group (10.8 mSv ± 0.58 vs 5.1 mSv ± 0.26, P = 0.00). LD-IMR images enabled lowest image noise and best subjective image quality scores of all 4 indices, when compared with RD images reconstructed with FBP (RD-FBP) images (all P < 0.05). LD images reconstructed with and with HIR (LD-HIR) images enabled higher score in subjective image quality of artifacts (P < 0.05), whereas it showed no difference in the other subjective image-quality indices and image noise. Significant higher image noise and lower score of subjective image quality were observed in LD-FBP images (all P < 0.05).Both IMR and HIR improved image quality of low-dose chest CT by comparison of routine dose images reconstructed with FBP. Meanwhile, IMR allows further image quality improvement than HIR.

Spectrum of Imaging Findings Following Bronchoscopic Intervention

Interventional pulmonology (IP) is a relatively new field that uses endoscopy and other technologies for both the diagnosis and treatment of pulmonary and thoracic conditions. IP is a continually developing field driven by clinical need as well as technological and therapeutic innovation. Developments in IP have increased both the efficacy and breadth of procedures that may be encountered by radiologists on periprocedural and postprocedural imaging. In this article, we will describe commonly performed IP procedures, with a focus on relevant imaging implications for radiologists.

Imaging of the central airways with bronchoscopic correlation: pictorial essay

A wide variety of pathologic processes, both benign and malignant, affect the central airways. These processes may be classified into 4 distinct groups: anatomic variants, lesions that result in focal or diffuse airway narrowing, and those that result in multinodular airway disorder. Key to the accurate assessment of the central airways is meticulous imaging technique, especially the routine acquisition of contiguous high-resolution, 1-mm to 1.5-mm images. These images enable high-definition axial, coronal, and sagittal reconstructions, as well as advanced imaging techniques, including minimum intensity projection images and virtual bronchoscopy. Current indications most commonly include patients presenting with signs and symptoms of possible central airway obstruction, with or without hemoptysis. In addition to diagnosing airway abnormalities, computed tomography (CT) also serves a critical complementary role to current bronchoscopic techniques for both diagnosing and treating airway lesions. Advantages of CT include noninvasive visualization of the extraluminal extent of lesions, as well as visualization of airways distal to central airways obstructions. As discussed and illustrated later, thorough knowledge of current bronchoscopic approaches to central airway disease is essential for optimal correlative CT interpretation.