Multislice CT Evaluation of Airway Stents

Self-Expandable Metal Stent in the Management of Malignant Airway Disorders

Background

Self-expanding metallic stent (SEMS) is a palliative therapy for patients with malignant central airway obstruction (CAO) or tracheoesophageal fistula (TEF). Despite this, many patients experience death shortly after SEMS placement.

Aims

We aimed to investigate the effect of SEMS on the palliative treatment between malignant CAO and malignant TEF patients and investigate the associated prognostic factors of the 3-month survival.

Methods

We performed a single-center, retrospective study of malignant CAO or TEF patients receiving SEMS placement. Clinical data were collected using the standardized data abstraction forms. Data were analyzed using SPSS 22.0. A two-sided P-value <0.05 was statistically significant.

Results

106 malignant patients (82 CAO and 24 TEF) receiving SEMS placement were included. The body mass index (BMI), hemoglobin levels, and albumin levels in the malignant TEF group were lower than in the malignant CAO group (all P < 0.05). The procalcitonin levels, C-reactive protein levels, and the proportion of inflammatory lesions were higher in the malignant TEF group than in the malignant CAO group (all P < 0.05). The proportion of symptomatic improvement after the SEMS placement was 97.6% in the malignant CAO group, whereas 50.0% in the malignant TEF group, with a significant difference (P = 0.000). Three months after SEMS placement, the survival rate at was 67.0%, significantly lower in the malignant TEF group than in the malignant CAO group (45.8% vs. 73.2%, P = 0.013). Multivariate analysis revealed that BMI [odds ratio (OR) = 1.841, 95% certificated interval (CI) (1.155-2.935), P = 0.010] and neutrophil percentage [OR = 0.936, 95% CI (0.883–0.993), P = 0.027] were the independent risk factors for patients who survived three months after SEMS placement.

Conclusions

We observed symptom improvement in malignant CAO and TEF patients after SEMS placement. The survival rate in malignant TEF patients after SEMS placement was low, probably due to aspiration pneumonitis and malnutrition. Therefore, we recommend more aggressive treatment modalities in patients with malignant TEF, such as strong antibiotics, nutrition support, and strategic ventilation. More studies are needed to investigate the prognostic factors in patients with malignant airway disorders receiving SEMS placement.

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.

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

Airway stents are increasingly used to treat symptomatic patients with obstructive tracheobronchial diseases who are not amenable to surgical resection or who have poor performance status, precluding them from resection. The most common conditions that are treated with tracheobronchial stents are primary lung cancer and metastatic disease. However, stents have also been used to treat patients with airway stenosis related to a variety of benign conditions, such as tracheobronchomalacia, relapsing polychondritis, postintubation tracheal stenosis, postoperative anastomotic stenosis, and granulomatous diseases. Additionally, airway stents can be used as a barrier method in the management of esophagorespiratory fistulas. Many types of stents are available from different manufacturers. Principally, they are classified as silicone; covered and uncovered metal; or hybrid, which are made of silicone and reinforced by metal rings. The advantages and disadvantages of each type of airway stent are carefully considered when choosing the most appropriate stent for each patient. Multidetector computed tomography plays an important role in determining the cause and assessing the location and extent of airway obstruction. Moreover, it is very accurate in its depiction of complications after airway stent placement.

Respiratory infections increase the risk of granulation tissue formation following airway stenting in patients with malignant airway obstruction

BACKGROUND

The most serious complications of airway stenting are long term, including infection and granulation tissue formation. However, to our knowledge, no studies have quantified the incidence rate of long-term complications for different stents.

METHODS

To compare the incidence of complications of different airway stents, we conducted a retrospective cohort study of all patients at our institution who had airway stenting for malignant airway obstruction from January 2005 to August 2010. Patients were excluded if more than one type of stent was in place at the same time. Complications recorded were lower respiratory tract infections, stent migration, granulation tissue, mucus plugging requiring intervention, tumor overgrowth, and stent fracture.

RESULTS

One hundred seventy-two patients with 195 stent procedures were included. Aero stents were associated with an increased risk of infection (hazard ratio [HR] = 1.98; 95% CI, 1.03-3.81; P = .041). Dumon silicone tube stents had an increased risk of migration (HR = 3.52; 95% CI, 1.41-8.82; P = .007). Silicone stents (HR = 3.32; 95% CI, 1.59-6.93; P = .001) and lower respiratory tract infections (HR = 5.69; 95% CI, 2.60-12.42; P < .001) increased the risk of granulation tissue. Lower respiratory tract infections were associated with decreased survival (HR = 1.57; 95% CI, 1.11-2.21; P = .011).

CONCLUSIONS

Significant differences exist among airway stents in terms of infection, migration, and granulation tissue formation. These complications, in turn, are associated with significant morbidity and mortality. Granulation tissue formation develops because of repetitive motion trauma and infection.

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.

Imaging-bronchoscopic correlations for interventional pulmonology

The improvements to patient care that can be achieved by combining advanced imaging techniques and bronchoscopy are considerable. In this regard, CT imaging often plays an indispensable role in both the selection of appropriate candidates tor therapy as well as the choice of optimal interventional techniques. However, it is apparent that alternate methods for evaluating the airways and lung including ultrasound and electromagnetic navigation will likely play an increasingly important diagnostic role, necessitating a thorough understanding of their advantages and limitations. Disease-specific applications for which imaging technologies, including CT and VB, are either currently routinely used or show the greatest promise are for suspected or diagnosed lung cancers, central and peripheral, and emphysema. It may be anticipated that with growing experience, the potential for additional indications of these remarkable technologies are likely to increase in the near future.

Tracheobronchomalacia in infants and children: multidetector CT evaluation

Tracheobronchomalacia (TBM) is the most common congenital central airway anomaly, but it frequently goes unrecognized or is misdiagnosed as other respiratory conditions such as asthma. Recent advances in multidetector computed tomography (CT) have enhanced the ability to noninvasively diagnose TBM with the potential to reduce the morbidity and mortality associated with this condition. Precise indications are evolving but may include symptomatic pediatric patients with known risk factors for TBM and patients with otherwise unexplained impaired exercise tolerance; recurrent lower airways infection; and therapy-resistant, irreversible, and/or atypical asthma. With multidetector CT, radiologists can now perform objective and quantitative assessment of TBM with accuracy similar to that of bronchoscopy, the reference standard for diagnosing this condition. Multidetector CT enables a comprehensive evaluation of pediatric patients suspected of having TBM by facilitating accurate diagnosis, determining the extent and degree of disease, identifying predisposing conditions, and providing objective pre- and postoperative assessments. In this article, the authors present a step-by-step primer of multidetector CT imaging for evaluating infants and children with suspected TBM, including clinical indications, patient preparation, multidetector CT techniques and protocols, two- and three-dimensional processing of multidetector CT data, and image interpretation. The major aim of this article is to facilitate the reader's ability to successfully employ multidetector CT imaging protocols for evaluation of TBM in infants and children in daily clinical practice.

Imaging-bronchoscopic correlations for interventional pulmonology

The development and rapid advancement of both bronchoscopic, CT and ultrasound imaging technology has had considerable impact on the management of a wide variety of pulmonary diseases. The synergy between these newer imaging modalities and advanced interventional endoscopic procedures has led to a revolution in diagnostic and therapeutic options in patients with both central and peripheral airway disease. Given the broad clinical implications of these technological advances, only the most important areas of interventional pulmonology in which imaging has had a major impact will be selectively reviewed to highlight fundamental principles.

Anesthetic considerations for airway stenting in adult patients

The attributable morbidity from central airway obstruction is significant. Airway stenting provides a therapeutic option to manage these complex lesions. This article focuses on the relevant anesthetic considerations of airway stenting in adult patients.

Airway stents in children

Airway obstruction in children is a rare, but difficult clinical problem, with no clear agreement on optimal therapeutic approach. Stenting of the airway has been used successfully in adults, and is an attractive alternative in children. Fundamental differences of pediatric compared to adult use include the benign nature of most stenoses, the narrow and soft airways of children, the required long-term tolerance and adaptation to growth. These differences may significantly alter the therapeutic balance, calling into question the precise role stents play in the treatment of airway obstruction in children. Stent placement can be technically demanding but is not exceedingly difficult. Experience is necessary to select the proper size and type of stent. Metal stents usually achieve airway patency and clinical improvement in the majority of cases, while this is less frequently the case with silicone stents. Some complications such as granulation and secretion retention seem to occur in most children after stent implantation. Unfortunately, severe complications including death have been reported in a significant proportion of children. Stent related mortality can be estimated at 12.9% from published data, but these include complication centered reports. The initial euphoria for airway stents in children has largely abated and most authors agree that they should only be employed in circumstances with no good alternatives. It is crucial that all surgical and medical alternatives are considered and the decision to place a stent is not made because other options are overlooked or not available locally. Stent use in a palliative setting has also been reported and is probably reasonable. Stents will only allow limited adaptation for the growth of pediatric airways by balloon dilatation. All metal stents should be considered as potentially permanent, and removal sometimes may only be possible through a surgical and sometimes risky approach.

[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.

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.