Virtual bronchoscopy: clinical applications and limitations

Role of Virtual Bronchoscopy in Evaluation of Suspected Foreign Body in Children's Tracheobronchial Tree

Introduction  The presence of foreign bodies in the airways remain a diagnostic challenge to healthcare professionals. They can become life threatening emergencies that require immediate intervention or go unnoticed for weeks and even months. Prevention is best but early recognition remains a critical factor in treatment of foreign body inhalation in children. Objective  To study the diagnostic advantages of virtual over rigid bronchoscopy in the evaluation of children with suspected foreign body in the tracheobronchial tree and plan for early management. Methods  A crossectional study conducted at a tertiary care hospital & medical college in India. A total 24 patients (0-12-years-old) who presented with complaints of sudden onset of coughing, choking, and breathing difficulty were included during the 2-year duration, from January 2018 to December 2019. All patients underwent virtual and rigid bronchoscopy. Results  In 8 patients, foreign bodies detected by virtual bronchoscopy were confirmed by rigid bronchoscopy. There was one case in which virtual bronchoscopy showed no foreign body, but rigid bronchoscopy detected it. In 15 cases virtual and rigid bronchoscopy did not show foreign bodies. The sensitivity, specificity, positive and negative predictive value of virtual bronchoscopy were 88.88, 100, 100, and 93.75%, respectively. Conclusions  Virtual bronchoscopy is less invasive and does not require general anesthesia but cost and availability are limitations. It can be used as method of investigation in children with suspected foreign body aspiration.

3D Virtual Bronchoscopy as an Aid to Airway Management in a Patient with Anterior Mediastinal Mass

ABSTRACT

Mediastinal masses pose one of the great challenges for any anesthesiologist during airway maintenance, underlining the need to devise a well-formulated plan to avoid perioperative complications. As a general rule, such patients are managed with spontaneous ventilation without the use of muscle relaxants and awake intubation. We report a case of a 66-year-old male with severe dyspnea, having a very large invasive anterior mediastinal mass, causing left lung collapse for urgent debulking surgery. The tracheobronchial compromise was ruled out using three-dimensional reconstruction on computed tomography imaging (virtual bronchoscopy) and that helped in using general anesthesia with muscle relaxation for subsequent endotracheal intubation and surgery.

Automated procedure assessing the accuracy of HRCT-PET registration applied in functional virtual bronchoscopy

Background

Bronchoscopy serves as direct visualisation of the airway. Virtual bronchoscopy provides similar visual information using a non-invasive imaging procedure(s). Early and accurate image-guided diagnosis requires the possible highest performance, which might be approximated by combining anatomical and functional imaging. This communication describes an advanced functional virtual bronchoscopic (fVB) method based on the registration of PET images to high-resolution diagnostic CT images instead of low-dose CT images of lower resolution obtained from PET/CT scans. PET/CT and diagnostic CT data were collected from 22 oncological patients to develop a computer-aided high-precision fVB. Registration of segmented images was performed using elastix.

Results

For virtual bronchoscopy, we used an in-house developed segmentation method. The quality of low- and high-dose CT image registrations was characterised by expert’s scoring the spatial distance of manually paired corresponding points and by eight voxel intensity-based (dis)similarity parameters. The distribution of (dis)similarity parameter correlating best with anatomic scoring was bootstrapped, and 95% confidence intervals were calculated separately for acceptable and insufficient registrations. We showed that mutual information (MI) of the eight investigated (dis)similarity parameters displayed the closest correlation with the anatomy-based distance metrics used to characterise the quality of image registrations. The 95% confidence intervals of the bootstrapped MI distribution were [0.15, 0.22] and [0.28, 0.37] for insufficient and acceptable registrations, respectively. In case of any new patient, a calculated MI value of registered low- and high-dose CT image pair within the [0.28, 0.37] or the [0.15, 0.22] interval would suggest acceptance or rejection, respectively, serving as an aid for the radiologist.

Conclusion

A computer-aided solution was proposed in order to reduce reliance on radiologist’s contribution for the approval of acceptable image registrations.

The effect of virtual endoscopy on diagnostic accuracy and airway management strategies in patients with head and neck pathology: a prospective cohort study

PURPOSE

There is growing evidence to suggest a deficiency in anesthesiologists' diagnosis of airway pathology and subsequent airway management planning, and conventional instruments have not shown increases in safety. Virtual endoscopy (VE) is a tool that can detail intraluminal anatomical "fly-through" information in a format visually similar to the flexible endoscopic views familiar to anesthesiologists. We aimed to determine the effect of VE on diagnostic accuracy and airway management strategies when compared with conventional tools.

METHODS

Clinical scenarios, along with computerized tomography (CT) imaging, were presented to 20 anesthesiologists, and structured questions were asked regarding diagnosis of airway pathology and airway management strategy. Virtual endoscopy videos were then provided and the questions were repeated. Following the CT and VE presentations, the anesthesiologists' responses involving diagnostic accuracy and airway management strategy were compared between the CT and VE techniques. Answers relating to the utility of VE were also sought.

RESULTS

Diagnostic accuracy was 54.1% with CT alone and increased to 67.7% when VE was added (P = 0.007). In 48% of cases, the addition of VE to clinical history and CT led to changes in airway management strategy (P < 0.001), and 90.6% of these changes were deemed more cautious (P < 0.001).

CONCLUSION

Virtual endoscopy improves the accuracy in diagnosis of airway pathology when compared with CT alone. Furthermore, it leads to more conservative and potentially safer airway management strategies in patients with head and neck pathology.

Airway Evaluation with Multidetector Computed Tomography Post-Processing Methods in Asthmatic Patients

Asthma is a chronic inflammatory obstructive airways disease. The disease occurs regardless of age and manifests with cough, attacks of breathlessness, and tightness in the chest. The pathophysiology of asthma is complex and still not fully understood. It is essential to find answers concerning the role of each part of the bronchial tree in asthma, especially the role of small bronchioles. With the development of newer generations of multidetector computed tomography (MDCT) and advanced post-processing methods it is possible to obtain more detailed images and gain insight into further aspects of asthma. MDCT post-processing methods can be divided into two-dimensional (2D) and three-dimensional (3D). In 2D projections, visualized hypodense regions correspond to the airway flow limitations. With the more advanced methods, such as multi planar reconstructions (MPR), images in different planes (axial, coronal, or sagittal) can be created. In the MPR technique only the voxels which are adjacent to each other in the predetermined plane can be extracted from the data set. Using the minimal/maximal intensity projections and shaded surface display, the volume of interest (VOI) can be extracted. High resolution CT scans can be used to create a more advanced imaging tool - the virtual bronchoscopy (VB). Using the VB makes it possible to visualize regions of obturation in the bronchi of up to the 5-8th generation. The MDCT with advanced post-processing methods is likely to assume an important role in the differential diagnosis of asthma, particularly when the diagnosis is dubious or hard to settle due to accompanying other lung diseases.

Cricotracheal Resection in a Patient with Severe Subglottic Stenosis - Advantages of a Temporary Non-Cannulated Tracheostomy

Background:

Stenosis in the area of the cricotracheal segment is still a challenging problem to be dealt with. Post-intubational cases mark an increase in recent years due to the advances in intensive care, thoracic surgery and neurosurgery departments.

Case Report:

This paper describes a case report of a patient with severe subglottic stenosis (grade III according to the Cotton-Myer scale), introduces a new option in cricotracheal resections - postoperative temporary non-cannulated tracheostomy and describes its advantages.

Conclusion:

This variation of classical operative techniques provides additional fixation of the trachea, thus relieving any transitory tension on the anastomosis; acts as a valve and decreases the air-pressure in the upper airways during coughing and sneezing in the post-operative period; and is an easy access point for video tracheoscopy of the anastomosis.

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.

CT based computerized identification and analysis of human airways: a review

As one of the most prevalent chronic disorders, airway disease is a major cause of morbidity and mortality worldwide. In order to understand its underlying mechanisms and to enable assessment of therapeutic efficacy of a variety of possible interventions, noninvasive investigation of the airways in a large number of subjects is of great research interest. Due to its high resolution in temporal and spatial domains, computed tomography (CT) has been widely used in clinical practices for studying the normal and abnormal manifestations of lung diseases, albeit there is a need to clearly demonstrate the benefits in light of the cost and radiation dose associated with CT examinations performed for the purpose of airway analysis. Whereas a single CT examination consists of a large number of images, manually identifying airway morphological characteristics and computing features to enable thorough investigations of airway and other lung diseases is very time-consuming and susceptible to errors. Hence, automated and semiautomated computerized analysis of human airways is becoming an important research area in medical imaging. A number of computerized techniques have been developed to date for the analysis of lung airways. In this review, we present a summary of the primary methods developed for computerized analysis of human airways, including airway segmentation, airway labeling, and airway morphometry, as well as a number of computer-aided clinical applications, such as virtual bronchoscopy. Both successes and underlying limitations of these approaches are discussed, while highlighting areas that may require additional work.

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.

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.

A new technique for the examination of tracheal tumors: the bronchoscopic turned around procedure

Flexible bronchoscopy is useful for confirming an endotracheal tumor. However, observation of the distal end of the tumor is difficult because of the presence of the lesion itself. Here we describe a technique that we termed "bronchoscopic turned around procedure," which can be used to observe the distal extent of the lesion using an ultrathin bronchoscope. The scope is passed distal to the endotracheal tumor and is flexed upward by 180 degrees in the trachea for full visualization of the distal extent of the lesion and the airway anatomy. We found this procedure to be an effective technique to assess surgical candidates by confirming the surface structure of the tracheal lumen, which cannot be obtained by computed tomography or virtual bronchoscopy.

Evaluation of computed tomography virtual bronchoscopy in paediatric tracheobronchial foreign body aspiration

OBJECTIVE

Virtual bronchoscopy is a noninvasive technique which provides an intraluminal view of the tracheobronchial tree. This study aimed to evaluate this technique in comparison with rigid bronchoscopy, in paediatric patients with tracheobronchial foreign bodies undetected by plain chest radiography.

METHODS

Plain chest radiography was initially performed in 40 children with suspected foreign body aspiration. Computed tomography virtual bronchoscopy was performed in the 20 in whom chest radiography appeared normal. Virtual bronchoscopic images were obtained. All patients underwent rigid bronchoscopy performed by an otolaryngologist blinded to the computed tomography virtual bronchoscopy findings, within 24 hours. Virtual bronchoscopic findings were then compared with the results of rigid bronchoscopy.

RESULTS

In 12 patients, foreign bodies detected by virtual bronchoscopy were confirmed by rigid bronchoscopy. In one case, a mucous plug was perceived as a foreign body on virtual bronchoscopy. In another case, a minute foreign body was missed on virtual bronchoscopy. The following parameters were calculated: sensitivity, 92.3 per cent; specificity, 85.7 per cent; validity, 90 per cent; positive likelihood ratio, 6.45; and negative likelihood ratio, 0.089.

CONCLUSION

In the presence of a positive clinical diagnosis and negative chest radiography, computed tomography virtual bronchoscopy must be considered in all cases of tracheobronchial foreign body aspiration, in order to avoid needless rigid bronchoscopy. Computed tomography virtual bronchoscopy is particularly useful in screening cases of occult foreign body aspiration, as it has high sensitivity, specificity and validity.

High-resolution visualization of airspace structures in intact mice via synchrotron phase-contrast X-ray imaging (PCXI)

Anatomical visualization of airspace-containing organs in intact small animals has been limited by the resolution and contrast available from current imaging methods such as X-ray, micro-computed tomography and magnetic resonance imaging. Determining structural relationships and detailed anatomy has therefore relied on suitable fixation, sectioning and histological processing. More complex and informative analyses such as orthogonal views of an organ and three-dimensional structure visualizations have required different animals and image sets, laboriously processed to gather this complementary structural information. Precise three-dimensional anatomical views have always been difficult to achieve in small animals. Here we report the ability of phase-contrast synchrotron X-ray imaging to provide detailed two- and three-dimensional visualization of airspace organ structures in intact animals. Using sub-micrometre square pixel charge-coupled device array detectors, the structure and anatomy of hard and soft tissues, and of airspaces, is readily available using phase-contrast synchrotron X-ray imaging. Moreover, software-controlled volume-reconstructions of tomographic images not only provide unsurpassed image clarity and detail, but also selectable anatomical views that cannot be obtained with established histological techniques. The morphology and structure of nasal and lung airways and the middle ear are illustrated in intact mice, using two- and three-dimensional representations. The utility of phase-contrast synchrotron X-ray imaging for noninvasively localizing objects implanted within airspaces, and the detection of gas bubbles transiting live airways, are other novel features of this visualization methodology. The coupling of phase-contrast synchrotron X-ray imaging technology with software-based reconstruction techniques holds promise for novel and high-resolution non-invasive examination of airspace anatomy in small animal models.

Importance of preoperative imaging with 64-row three-dimensional multidetector computed tomography for safer video-assisted thoracic surgery in lung cancer

PURPOSE

Video-assisted thoracic surgery (VATS) has recently been adopted for complicated anatomical lung resections. During these thoracoscopic procedures, surgeons view the operative field on a two-dimensional (2-D) video monitor and cannot palpate the organ directly, thus frequently encountering anatomical difficulties. This study aimed to estimate the usefulness of preoperative three-dimensional (3-D) imaging of thoracic organs.

METHODS

We compared the preoperative 64-row three-dimensional multidetector computed tomography (3DMDCT) findings of lung cancer-affected thoracic organs to the operative findings.

RESULTS

In comparison to the operative findings, the branches of pulmonary arteries, veins, and bronchi were well defined in the 3D-MDCT images of 27 patients.

CONCLUSION

3D-MDCT imaging is useful for preoperatively understanding the individual thoracic anatomy in lung cancer surgery. This modality can therefore contribute to safer anatomical pulmonary operations, especially in VATS.

Comparison of virtual and fiberoptic bronchoscopy in the management of airway stenosis

Noninvasive imaging methods can be valuable tools for diagnosing thoracic diseases, especially malignancies. The aim of this study was to compare the effectiveness of conventional and virtual bronchoscopy in the follow-up of patients with large airway stenosis. Twenty-three consecutive patients with stenoses of the trachea and/or the main bronchi were enrolled in this prospective observer study. The causes of stenosis included malignant or benign tumours, goiter, and postintubation stenoses. Patients were evaluated before and after treatment (which included mechanical dilation, laser photocoagulation, stent implantation, radiotherapy, chemotherapy, and surgical resection). The mean time between baseline and follow-up endoscopy was 140 days. No significant differences were observed between the estimated and measured data from bronchofibroscopy and virtual bronchoscopy. Exact measurement of stenoses was performed with virtual bronchoscopy.

[Virtual pleuroscopy of diaphragmatic pleura: myth or reality?]

PURPOSE

Evaluate the feasibility of the virtual pleuroscopy (VP) in the detection of the pleural plaques.

METHOD AND MATERIALS

Twenty consecutive patients, having asbestos exposure, explored by unenhanced multidetector CT-scan (Siemens, Sensation 16). The imaging parameters were as follows: beam width, 12 mm; beam pitch, 1; and reconstruction thickness, 1mm every 0.8mm at 120 kV and 180 mA. The image display used a surface-rendering algorithm and produced perspective red-scale images with a matrix of 512 x 512. Each VP image simulated a coned-down view, with a variable cone angle to explore the diaphragmatic pleura. The camera was placed 1 to 2 cm above the diaphragmatic dome. Four views are studied by diaphragm: crâniocaudal, lateral tangential, anterior and posterior. The observed virtual pleura aspect was classified in 5 groups (gr): gr 1: Rib band, gr 2: lobulated pleural thickening, gr 3: spicular, gr 4: plaques and gr 5: nodules. The results were compared to the other MDCT images using multiplanar reformatting.

RESULTS

The visualization of each diaphragm was optimal (35/40; 87.5%), limited (3/40; round atelectasis and asbestosis) or impossible (2/40; asbestosis). The classifications of the studied 38 diaphragmatic pleura were: gr 1 (n=15), gr 2 (n=5), gr 3 (n=11), gr 4 (n=7), gr 5 (n=0). The MDCT analysis showed normal pleura for both gr 1 and gr 2, a confirmed or beginning of fibrosis for gr 3 and confirmed the presence of pleural plaques on the diaphragmatic pleura in all cases of gr 4.

CONCLUSION

The virtual pleuroscopy is a reality. It is a feasible technique. Other studies are necessary to confirm these preliminary results.