Virtual Bronchoscopy: Accuracy and Usefulness—An Overview

Lung Imaging in COPD Part 2: Emerging Concepts

The diagnosis, prognostication, and differentiation of phenotypes of COPD can be facilitated by CT scan imaging of the chest. CT scan imaging of the chest is a prerequisite for lung volume reduction surgery and lung transplantation. Quantitative analysis can be used to evaluate extent of disease progression. Evolving imaging techniques include micro-CT scan, ultra-high-resolution and photon-counting CT scan imaging, and MRI. Potential advantages of these newer techniques include improved resolution, prediction of reversibility, and obviation of radiation exposure. This article discusses important emerging techniques in imaging patients with COPD. The clinical usefulness of these emerging techniques as they stand today are tabulated for the benefit of the practicing pulmonologist.

BronchoX: bronchoscopy exploration software for biopsy intervention planning

Virtual bronchoscopy (VB) is a non-invasive exploration tool for intervention planning and navigation of possible pulmonary lesions (PLs). A VB software involves the location of a PL and the calculation of a route, starting from the trachea, to reach it. The selection of a VB software might be a complex process, and there is no consensus in the community of medical software developers in which is the best-suited system to use or framework to choose. The authors present Bronchoscopy Exploration (BronchoX), a VB software to plan biopsy interventions that generate physician-readable instructions to reach the PLs. The authors' solution is open source, multiplatform, and extensible for future functionalities, designed by their multidisciplinary research and development group. BronchoX is a compound of different algorithms for segmentation, visualisation, and navigation of the respiratory tract. Performed results are a focus on the test the effectiveness of their proposal as an exploration software, also to measure its accuracy as a guiding system to reach PLs. Then, 40 different virtual planning paths were created to guide physicians until distal bronchioles. These results provide a functional software for BronchoX and demonstrate how following simple instructions is possible to reach distal lesions from the trachea.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Diagnostic performance of multidetector computed tomography for foreign body aspiration in children

OBJECTIVE

To evaluate the sensitivity of multidetector computed tomography for confirming suspected foreign body aspiration into the airways in children.

METHOD

We conducted a multicentre prospective study of 303 children evaluated using multidetector computed tomography with axial analysis complemented by multiplanar reconstruction when required. The images were read by a radiologist before endoscopy then reviewed later by a senior radiologist blinded to the endoscopy findings. Endoscopy was performed routinely.

RESULTS

Foreign bodies were found by endoscopy in 70 of the 303 children. The initial multidetector computed tomography reading was 94% sensitive and 95% specific. For the review, the images for 91 patients were excluded because of motion blurring or absence of larynx visualisation; in the remaining 212 patients, sensitivity was 98% and specificity 97%.

CONCLUSION

Multidetector computed tomography as performed in our patients cannot replace endoscopy, which remains the reference standard. Nevertheless, multidetector computed tomography is sufficiently sensitive to be of value when foreign body aspiration is not considered initially or when endoscopy is likely to prove challenging.

Usefulness of computed tomography virtual bronchoscopy in the evaluation of bronchi divisions

Background:

Since introduction of multislice CT scanners into clinical practice, virtual brochoscopy has gained a lot of quality and diagnostic potential. Nevertheless it does not have established place in diagnostics of tracheal and bronchi disorders and its potential has not been examined enough. Nowadays a majority of bronchial tree variants and lesions are revealed by bronchofiberoscopy, which is an objective and a relatively safe method, but has side effects, especially in higher-risk subjects. Therefore noninvasive techniques enabling evaluation of airways should be consistently developed and updated.

Material/Methods:

Material consisted of 100 adults (45 female, 55 male) aged between 18 and 65 years (mean 40 years, median 40.5 years, SD 14.02), who underwent chest CT examination by means of a 16-slice scanner. Every patient had normal appearance of chest organs, with the exception of minor abnormalities that did not alter airways route.

Divisions of bronchial tree to segmental level were evaluated and assigned to particular types by means of virtual bronchoscopy projection. In case of difficulties MPR or MinIP projection was used.

Results:

The frequency of lobar bronchi divisions other than the typical ones was in: right upper lobar bronchi 45%, left 55%; middle lobar bronchi 21%, lingula 26%; right lower lobar bronchi 28%, left 29%. Subsuperior bronchus or bronchi were found on the right side in 44% and on the left side in 37%. No dependency between types of bronchial divisions on different levels was found.

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.

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.

Utility of multidetector CT and virtual bronchoscopy in tracheobronchial obstruction in children

PURPOSE

The aim of this study was to evaluate the potential use of multidetector CT (MDCT) and virtual bronchoscopy (VB) in the evaluation of tracheobronchial patency in children with suspected bronchial obstruction and to compare its findings with fibreoptic/rigid bronchoscopy or surgery.

PATIENTS AND METHODS

A total of 43 children (15 girls, 28 boys) with clinically suspected bronchial obstruction underwent contrast enhanced MDCT, using an age- and weight- adjusted low dose protocol. Post-processing was performed and VB and multiplanar reformations (MPR) were obtained at the same sitting. Findings obtained at MDCT and VB were compared with fibreoptic/rigid bronchoscopy and surgery.

RESULTS

Obstructive pathology was found in 26 children, which included endoluminal foreign body, mucus plugs in 13 children, endobronchial tumour in three children and extrinsic compression (lymph node, aberrant Vessels, mediastinal cysts/tumours) of the tracheobronchial tree in 10 children. In 17 children, no obstructive lesion was identified. Excellent positive correlation was obtained, between MDCT-VB and bronchoscopy/surgery, however, in one child with endobronchial obstruction caused by tracheitis, low dose MDCT-VB was normal, but bronchoscopy revealed granularity and plaques.

CONCLUSION

MDCT-Virtual bronchoscopy is useful in evaluating bronchial stenosis and obstruction caused by both endoluminal pathology and external compression and has the advantage of looking beyond stenosis. Its main application lies in providing the exact location of suspected foreign body, prior to bronchoscopy. However, it fails to disclose exact nature of obstructing pathology.

Diagnosis of airway malacia by virtual bronchoscopy

The study was aimed to identify the role of virtual bronchoscopy in detection of airway malacia in children. In a pre-experimental study over 3 years (from Nov. 2003 to Oct. 2006), 35 consecutive patients were presented to Tabriz Children's Hospital with clinical manifestations of airway malacia, examined by the technique of virtual bronchoscopy. Thirty five patients including 23 males and 12 females with the mean age of 3.7 +/- 1.6 months were studied. The presence of airway malacia and its location and severity were determined by virtual bronchoscopy in all studied cases; that revealed: laryngomalacia, bronchomalacia, tracheomalacia, laryngotracheomalacia and laryngobronchomalacia in 42.8, 25.7, 20, 8.6 and 2.9% of patients, respectively. Virtual bronchoscopy is a non-invasive, accurate and rapid imaging technique with an excellent validity for diagnosis of airway malacia and stenosis, therefore it can replace conventional bronchoscopy.

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

OBJECTIVE

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

CONCLUSIONS

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

Inhaled foreign bodies in pediatric patients: review of personal experience

BACKGROUND

Foreign bodies (FBs) are a life-threatening event in children that require early diagnosis and prompt successful management. The ideal means of FB removal is rigid bronchoscopy under general anesthesia, although the choice between spontaneous or controlled breathing and the type of drug used are still subjects of discussion. We made a review of the literature and report our experience on FB inhalation, nature and location of FB, diagnostic method, prediction, perioperative complications, type of anesthesia, ventilation and total duration of the surgical procedure.

METHODS

Forty-six children undergoing rigid bronchoscopy for suspect FB aspiration were retrospectively assessed. Relevant clinical and radiological findings were retrieved. During endoscopic procedures induction and maintenance of anesthesia were performed by intravenous or volatile drugs associated with topical airway lidocaine under spontaneous breathing.

RESULTS

The most common symptoms were cough and dyspnea. Radiological examination was beneficial in 34 patients. At bronchoscopy, organic and inorganic FBs were located largely in bronchial tree and removed in 40 of the 46 children. All patients maintained spontaneous ventilation using volatile and intravenous anesthesia in 22 and 24 children, respectively. The mean surgical time was 79 min. Perioperative complications such as bronchospasm, bleeding and desaturation were observed in five patients.

CONCLUSIONS

FB inhalation is an uncommon life-threatening event in pediatric patients that can manifest with various symptoms. Rigid bronchoscopy is the procedure of choice for diagnosis and management of FB inhalation in pediatric patients. Spontaneous ventilation can be considered safe, using either volatile or intravenous agents. Perioperative complications were not correlated with either the choice of agent (volatile or intravenous) or the duration of surgery. A close collaboration between anesthesiologists and otorhinolaryngologists and a long-standing experience in pediatric airway emergencies are the key factors for obtaining good results.

Virtual bronchoscopy: clinical applications and limitations

Virtual bronchoscopy (VB) is a term that describes a variety of software-based three-dimensional visualizations created from noninvasive medical imaging methods such as CT or MRI scans, with the goal of creating results similar to minimally invasive bronchoscopy procedures of the trachea and upper airways. This technique offers a detailed, noninvasive view of the airways, with reduced risk of infection or perforation, and facilitates preoperative planning for airway interventions that would otherwise not be possible. It is unlikely that VB will replace fiberoptic bronchoscopy; however, as VB techniques become more sophisticated and as sufficient computing and imaging power become more readily available, noninvasive visualization of the airways will play an important and useful role in the evaluation of airway diseases in well defined clinical situations.

Utilization of low-dose multidetector CT and virtual bronchoscopy in children with suspected foreign body aspiration

BACKGROUND

Foreign body aspiration is common in children, especially those under 3 years of age. Chest radiography and CT are the main imaging modalities for the evaluation of these children. Management of children with suspected foreign body aspiration (SFBA) mainly depends on radiological findings.

OBJECTIVE

To investigate the potential use of low-dose multidetector CT (MDCT) and virtual bronchoscopy (VB) in the evaluation and management of SFBA in children.

MATERIALS AND METHODS

Included in the study were 37 children (17 girls, 20 boys; age 4 months to 10 years, mean 32 months) with SFBA. Chest radiographs were obtained prior to MDCT in all patients. MDCT was performed using a low-dose technique. VB images were obtained in the same session. Conventional bronchoscopy (CB) was performed within 24 h on patients in whom an obstructive abnormality had been found by MDCT and VB.

RESULTS

Obstructive pathology was found in 16 (43.25%) of the 37 patients using MDCT and VB. In 13 of these patients, foreign bodies were detected and removed via CB. The foreign bodies were located in the right main bronchus (n = 5), in the bronchus intermedius (n = 6), in the medial segment of the middle lobe bronchus (n = 1), and in the left main bronchus (n = 1). In the remaining three patients, the diagnosis was false-positive for an obstructive pathology by MDCT and VB; the final diagnoses were secretions (n = 2) and schwannoma (n = 1), as demonstrated by CB. In 21 patients in whom no obstructive pathology was detected by MDCT and VB, CB was not performed. These patients were followed for 5-20 months without any recurrent obstructive symptomatology.

CONCLUSIONS

Low-dose MDCT and VB are non-invasive radiological modalities that can be used easily in the investigation of SFBA in children. MDCT and VB provide the exact location of the obstructive pathology prior to CB. If obstructive pathology is depicted with MDCT and VB, CB should be performed either for confirmation of the diagnosis or for the diagnosis of an alternative cause for the obstruction. In cases where no obstructive pathology is detected by MDCT and VB, CB may not be clinically useful.

3D navigation of CTVE and correction of MinIP methods in non-invasive diagnostic detection

Navigation is important in Computed Tomography Virtual Endoscopy (CTVE) functions. Existing navigation methods involve planning and pre-calculating of a fixed path before the viewpoint flight inside the targeted organs. This includes path construction, centering, smoothing and multi-branch processing. This paper proposes a 3D navigation method which was achieved by utilizing the compatibility of the 3D navigation and the ray casting 3D rendering method, without the necessity of planning and pre-calculating a fixed path, eliminating the multi-branch problems. In our 3D navigation method, the viewpoint direction and location are tracked in real time when the viewpoint is inside the organs. At the same time it presents and controls the direction changes and location changes of the viewpoint in x, y, z dimensions. With interactive control of the viewpoint, it can fly in any direction in 3D, not only along a fixed path, thus eliminating multi-branch problems. The viewpoint locations and directions will change smoothly and will be used to calculate the current scene of CTVE. Accelerated ray casting is used to render 3D scenes, which is compatible with the 3D navigation method. In Minimum Intensity Projection (MinIP) applications, if the conventional MinIP reconstruction method is used, realistic results cannot be achieved when they are rotated in multi-directions because the Computed Tomography (CT) images always contain empty regions surrounding the tissue regions. The conventional MinIP reconstruction algorithm always chalks up a minimum intensity voxel which relates to the empty regions instead of the tissue regions. To solve such valid voxel searching problems, seed-filling algorithms are used to fill the empty regions of each slice automatically. The empty voxels are labeled automatically and are avoided in MinIP calculation to gain correct results in all directions.

ADVANCED VIRTUAL ENDOSCOPY FORENDOSCOPIC TRANSSPHENOIDAL PITUITARY SURGERY

OBJECTIVE

Virtual endoscopy (vE) is the navigation of a camera through a virtual anatomical space that is computationally reconstructed from radiological image data. Inside this three-dimensional space, arbitrary movements and adaptations of viewing parameters are possible. Thereby, vE can be used for noninvasive diagnostic purposes and for simulation of surgical tasks. This article describes the development of an advanced system of vE for endoscopic transsphenoidal pituitary surgery and its application to teaching, training, and in the routine clinical setting.

METHODS

The vE system was applied to a series of 35 patients with pituitary pathology (32 adenomas, three Rathke's cleft cysts) operated endoscopically via the transsphenoidal route at the Department of Neurosurgery of the Medical University Vienna between 2004 and 2006.

RESULTS

The virtual endoscopic images correlated well with the intraoperative view. For the transsphenoidal approach, vE improved intraoperative orientation by depicting anatomical landmarks and variations. For planning a safe and tailored opening of the sellar floor, transparent visualization of the pituitary adenoma and the normal gland in relation to the internal carotid arteries was useful.

CONCLUSION

According to our experience, vE can be a valuable tool for endoscopic transsphenoidal pituitary surgery for training purposes and preoperative planning. For the novice, it can act as a simulator for endoscopic anatomy and for training surgical tasks. For the experienced pituitary surgeon, vE can depict the individual patient's anatomy, and may, therefore, improve intraoperative orientation. By prospectively visualizing unpredictable anatomical variations, vE may increase the safety of this surgical procedure.