Interbronchoscopist variability in endobronchial path selection: a simulation study

Comparison of Efficacy and Safety of Different Guided Technologies Combined With Ultrathin Bronchoscopic Biopsy for Peripheral Pulmonary Lesions

INTRODUCTION

Various bronchoscopic guidance techniques have emerged to improve the diagnostic yield of peripheral pulmonary lesions (PPLs), especially when combined with ultra-thin bronchoscopy. However, uncertainties exists in the convenience, accuracy rate, and complications of these techniques. We compared the feasibility, accuracy rate, and complication rates of transbronchial biopsy of PPLs sampled by the standard thin-layer CT navigation combined with ultrathin bronchoscopy (CTNUTB), the Lungpro virtual navigation combined with ultrathin bronchoscopy (VNUTB), and electromagnetic navigation combined with ultrathin bronchoscopy (ENUTB).

METHODS

Retrospectively identified were 256 patients sampled with transbronchial biopsy of PPLs. Eligible patients referred for CTNUTB, VNUTB, and ENUTB from January 2017 to December 2021 were included. We comprehensively compared the accuracy rate, feasibility, and complication rates for each method.

RESULTS

There was no significant difference in the accuracy rate of CTNUTB, VNUTB, and ENUTB (p = 0.293). The operation time via Lungpro navigation was the shortest (14.4 min, p < 0.001). The planning time via CT planning was the shortest (7.36 min, p < 0.001). There was no difference in the incidence of complications such as hemorrhage, pneumonia, and pneumothorax (p = 0.123). Besides, ENUTB costs more than $2000, while CTNUTB and VNUTB cost only about $130-230.

CONCLUSION

CTNUTB is still the main bronchoscopy method we recommended, which has low cost, simple operation, and safety no less than the others. In contrast, ENUTB provides a higher accuracy rate for small diameter nodules (less than 2 cm), which has a high use value and is worth promoting in the future.

3D airway geometry analysis of factors in airway navigation failure for lung nodules

BACKGROUND

This study aimed to quantitatively reveal contributing factors to airway navigation failure during radial probe endobronchial ultrasound (R-EBUS) by using geometric analysis in a three-dimensional (3D) space and to investigate the clinical feasibility of prediction models for airway navigation failure.

METHODS

We retrospectively reviewed patients who underwent R-EBUS between January 2017 and December 2018. Geometric quantification was analyzed using in-house software built with open-source python libraries including the Vascular Modeling Toolkit ( http://www.vmtk.org ), simple insight toolkit ( https://sitk.org ), and sci-kit image ( https://scikit-image.org ). We used a machine learning-based approach to explore the utility of these significant factors.

RESULTS

Of the 491 patients who were eligible for analysis (mean age, 65 years +/- 11 [standard deviation]; 274 men), the target lesion was reached in 434 and was not reached in 57. Twenty-seven patients in the failure group were matched with 27 patients in the success group based on propensity scores. Bifurcation angle at the target branch, the least diameter of the last section, and the curvature of the last section are the most significant and stable factors for airway navigation failure. The support vector machine can predict airway navigation failure with an average area under the curve of 0.803.

CONCLUSIONS

Geometric analysis in 3D space revealed that a large bifurcation angle and a narrow and tortuous structure of the closest bronchus from the lesion are associated with airway navigation failure during R-EBUS. The models developed using quantitative computer tomography scan imaging show the potential to predict airway navigation failure.

Bronchoscopic Strategies to Improve Diagnostic Yield in Pulmonary Tuberculosis Patients

In cases where pulmonary tuberculosis (PTB) is not microbiologically diagnosed via sputum specimens, bronchoscopy has been the conventional method to enhance diagnostic rates. Although the additional benefit of bronchoscopy in diagnosing PTB is well-known, its overall effectiveness remains suboptimal. This review introduces several strategies for improving PTB diagnosis via bronchoscopy. First, it discusses how bronchoalveolar lavage or an increased number of bronchial washings can increase specimen abundance. Second, it explores how thin or ultrathin bronchoscopes can achieve specimen acquisition closer to tuberculosis (TB) lesions. Third, it highlights the importance of conducting more sensitive TB-polymerase chain reaction tests on bronchoscopic specimens, including the Xpert MTB/RIF assay and the Xpert MTB/RIF Ultra assay. Finally, it surveys the implementation of endobronchial ultrasound with a guide sheath for tuberculomas, collection of post-bronchoscopy sputum, and reduced use of lidocaine for local anesthesia. A strategic combination of these approaches may enhance the diagnostic rates in PTB patients undergoing bronchoscopy.

Artificial intelligence in interventional pulmonology

PURPOSE OF REVIEW

In recent years, there has been remarkable progress in the field of artificial intelligence technology. Artificial intelligence applications have been extensively researched and actively implemented across various domains within healthcare. This study reviews the current state of artificial intelligence research in interventional pulmonology and engages in a discussion to comprehend its capabilities and implications.

RECENT FINDINGS

Deep learning, a subset of artificial intelligence, has found extensive applications in recent years, enabling highly accurate identification and labeling of bronchial segments solely from intraluminal bronchial images. Furthermore, research has explored the use of artificial intelligence for the analysis of endobronchial ultrasound images, achieving a high degree of accuracy in distinguishing between benign and malignant targets within ultrasound images. These advancements have become possible due to the increased computational power of modern systems and the utilization of vast datasets, facilitating detections and predictions with greater precision and speed.

SUMMARY

Artificial intelligence integration into interventional pulmonology has the potential to enhance diagnostic accuracy and patient safety, ultimately leading to improved patient outcomes. However, the clinical impacts of artificial intelligence enhanced procedures remain unassessed. Additional research is necessary to evaluate both the advantages and disadvantages of artificial intelligence in the field of interventional pulmonology.

Bronchial Washing Using a Thin Versus a Thick Bronchoscope to Diagnose Pulmonary Tuberculosis: A Randomized Trial

BACKGROUND

This study was performed to evaluate the efficacy of using a thin bronchoscope for the diagnosis of pulmonary tuberculosis (PTB).

METHODS

Between March 2019 and November 2021, we prospectively enrolled participants with suspected PTB whose sputum acid-fast bacilli (AFB) smear and tuberculosis (TB) polymerase chain reaction (PCR) tests were negative or who could not produce self-expectorated sputum. Participants were randomized to a control group (bronchial washing [BW] using a 5.9-mm conventional bronchoscope guided by chest computed tomography) or an investigational group (BW using a 4.0-mm thin bronchoscope under virtual bronchoscopic navigation guidance). The primary outcome was detection of TB in BW fluid, defined as a positive result in the Xpert MTB/RIF assay. The secondary outcomes included AFB smear and Mycobacterium tuberculosis culture positivity, time to treatment initiation, and bronchoscopy-related complications.

RESULTS

In total, 85 participants were included in the final analysis (43 in the control group and 42 in the investigational group). Twenty-three and 29, respectively, were finally diagnosed with PTB. The TB detection rate in BW fluid was higher in the investigational group (72.4% vs 43.5%, P = .035). Mycobacterium tuberculosis culture positivity was also higher in the investigational group (79.3% vs 52.2%, P = .038). No participants required premature bronchoscopy termination because of complications. Of the participants with PTB, the time to treatment initiation was shorter in the investigational group (median, 2.0 days vs 4.0 days, P = .001).

CONCLUSIONS

BW using a thin bronchoscope increases the TB detection rate in patients with PTB compared to conventional bronchoscopy. Clinical Trials Registration.ȃNCT03802812.

Efficient procedure planning for comprehensive lymph node staging bronchoscopy

Purpose: For a patient at risk of having lung cancer, accurate disease staging is vital as it dictates disease prognosis and treatment. Accurate staging requires a comprehensive sampling of lymph nodes within the chest via bronchoscopy. Unfortunately, physicians are generally unable to plan and perform sufficiently comprehensive procedures to ensure accurate disease staging. We propose a method for planning comprehensive lymph node staging procedures. Approach: Drawing on a patient's chest CT scan, the method derives a multi-destination tour for efficient navigation to a set of lymph nodes. We formulate the planning task as a traveling salesman problem. To solve the problem, we apply the concept of ant colony optimization (ACO) to derive an efficient airway tour connecting the target nodes. The method has three main steps: (1) CT preprocessing, to define important chest anatomy; (2) graph and staging zone construction, to set up the necessary data structures and clinical constraints; and (3) tour computation, to derive the staging plan. The plan conforms to the world standard International Association for the Study of Lung Cancer (IASLC) lymph node map and recommended clinical staging guidelines. Results: Tests with a patient database indicate that the method derives optimal or near-optimal tours in under a few seconds, regardless of the number of target lymph nodes (mean tour length = 1.4% longer than the optimum). A brute force optimal search, on the other hand, generally cannot reach a solution in under 10 min. for patients exhibiting > 16 nodes, and other methods provide poor solutions. We also demonstrate the method's utility in an image-guided bronchoscopy system. Conclusions: The method provides an efficient computational approach for planning a comprehensive lymph node staging bronchoscopy. In addition, the method shows promise for driving an image-guided bronchoscopy system or robotics-assisted bronchoscopy system tailored to lymph node staging.

Findings of virtual bronchoscopic navigation can predict the diagnostic rate of primary lung cancer by bronchoscopy in patients with peripheral lung lesions

BACKGROUND

Despite being minimally invasive, bronchoscopy does not always result in pathological specimens being obtained. Therefore, we investigated whether virtual bronchoscopic navigation (VBN) findings were associated with the rate of diagnosis of primary lung cancer by bronchoscopy in patients with peripheral lung lesions.

METHODS

This study included patients with suspected malignant peripheral lung lesions who underwent bronchoscopy at St. Luke's International Hospital between October 2013 and March 2020. Patients diagnosed with primary lung cancer were grouped according to whether their pathology could be diagnosed by bronchoscopy, and their clinical factors were compared. In addition, the distance between the edge of the lesion and the nearest branch ("distance by VBN") was calculated. The distance by VBN and various clinical factors were compared with the diagnostic rates of primary lung cancer.

RESULTS

The study included 523 patients with 578 lesions. After excluding 55 patients who underwent multiple bronchoscopies, 381 patients were diagnosed with primary lung cancer. The diagnostic rate by bronchoscopy was 71.1% (271/381). Multivariate analysis revealed that the lesion diameter (odds ratio [OR] 1.107), distance by VBN (OR 0.94) and lesion structure (solid lesion or ground-glass nodule; OR 2.988) influenced the risk of a lung cancer diagnosis. The area under the receiver operating characteristic curve for diagnosis based on lesion diameter and distance by VBN was 0.810.

CONCLUSION

The distance by VBN and lesion diameter were predictive of the diagnostic rates of primary lung cancer by bronchoscopy in patients with peripheral lung lesions.

A Direct Comparative Study of Bronchoscopic Navigation Planning Platforms for Peripheral Lung Navigation: The ATLAS Study

BACKGROUND

The use of mapping to guide peripheral lung navigation (PLN) represents an advance in the management of peripheral pulmonary lesions (PPL). Software has been developed to virtually reconstruct computed tomography images into 3-dimensional airway maps and generate navigation pathways to target PPL. Despite this there remain significant gaps in understanding the factors associated with navigation success and failure including the cartographic performance characteristics of these software algorithms. This study was designed to determine whether differences exist when comparing PLN mapping platforms.

METHODS

An observational direct comparison was performed to evaluate navigation planning software packages for the lung. The primary endpoint was distance from the terminal end of the virtual navigation pathway to the target PPL. Secondary endpoints included distal virtual and segmental airway generations built to the target and/or in each lung.

RESULTS

Twenty-five patient chest computed tomography scans with 41 PPL were evaluated. Virtual airway and navigation pathway maps were generated for each scan/nodule across all platforms. Virtual navigation pathway comparison revealed differences in the distance from the terminal end of the navigation pathway to the target PPL (robotic bronchoscopy 9.4 mm vs. tip-tracked electromagnetic navigation 14.2 mm vs. catheter based electromagnetic navigation 17.2 mm, P=0.0005) and in the generation of complete distal airway maps.

CONCLUSION

Comparing PLN planning software revealed significant differences in the generation of virtual airway and navigation maps. These differences may play an unrecognized role in the accurate PLN and biopsy of PPL. Further prospective trials are needed to quantify the effect of the differences reported.

The superiority of manual over automated methods in identifying bronchial trees on identical CT images

The purpose of this study was to compare a manual bronchoscopic navigation technique, the direct oblique method (DOM), with conventional virtual bronchoscopic navigation software in terms of bronchial identification ability involving reconstruction of a whole bronchial tree from identical CT images. A whole bronchial tree was drawn using manual bronchial recognition with the DOM. The tree was compared with that reconstructed by SYNAPSE VINCENT bronchoscopic navigation-dedicated software. The number of bronchial generations at each terminal tip was then compared between the two approaches. Physicians spent 20 h tracing all bronchi on CT scan images and obtained a bronchial tree. The hand-made bronchial tree had five times the number of tips as that reconstructed by automatic bronchial recognition (1482 vs. 279 tips, respectively). The number of bronchial generations prior to each terminal tip was larger with the DOM than with VINCENT (median, 10; interquartile range (IQR), 9–11 vs. median, 5; IQR, 5–7, respectively; p-value < 0.001). Using the CT image data in this case, manual bronchial recognition with the DOM identified more bronchi than automatic bronchial recognition. This result implies that manual bronchial recognition is a valid basis for detailed bronchoscopic navigation analysis.

Efficacy and safety of virtual bronchoscopic navigation with fused fluoroscopy and vessel mapping for access of pulmonary lesions

BACKGROUND AND OBJECTIVE

Virtual bronchoscopic navigation (VBN) with fused fluoroscopy and vessel mapping provides a point of entry (POE) for puncturing airway wall to biopsy lesions. The study was designed to evaluate the safety and efficacy of this technology to diagnose peripheral pulmonary lesions.

METHODS

It was a prospective, single-arm, multicentre study. Patients underwent lesions biopsy with the Archimedes® VBN System via a POE using one of the two techniques: (1) bronchoscopic transparenchymal nodule access (BTPNA) and (2) guided transbronchial needle aspiration (TBNA). Biopsy yield, sampling yield and diagnostic yield were mainly determined in lesions biopsy attempted.

RESULTS

One hundred and thirty patients underwent anaesthesia and constituted the intention-to-treat population. One hundred and four patients with 114 lesions had biopsy attempted. Mean lesion size was 2.4 ± 1.13 cm. Sufficient tissue samples were obtained from 86 lesions with a biopsy yield of 75.4%. Nevertheless, sufficient samples for diagnosis based on histology ± cytology were obtained from 107 lesions with a sampling yield of 93.9%. Follow-up was conducted for more than 1 year, with a diagnostic yield of 75.4% and 72.8%, respectively, on high and low estimate with consideration of three lesions without follow-up. Two (1.9%) pneumothoraxes and one (1.0%) mild bleeding occurred.

CONCLUSION

BTPNA and guided TBNA contribute to safe and effective sampling of peripheral pulmonary lesions. A relatively high biopsy yield was obtained independent of the presence or absence of a bronchus sign (BS), and high sampling yield and diagnostic yield were obtained independent of location, lesion size and presence or absence of a BS.

Pilot study using virtual 4-D tracking electromagnetic navigation bronchoscopy in the diagnosis of pulmonary nodules: a single center prospective study

Background

Electromagnetic navigation bronchoscopy (ENB) is a navigation technology intended to improve the diagnostic yield of pulmonary nodules. However, nodule displacement due to respiratory motion may compromise the accuracy of the navigation guidance. The Veran SPiNDrive ENB system employs respiratory-gating (4D-tracking) to compensate for this motion. The aim of the present study was to evaluate the diagnostic performance and safety of the Veran SPiNDrive system for biopsy of pulmonary nodules.

Methods

Adult patients with pulmonary nodules of ≥1 cm were enrolled at a single center. Both conventional bronchoscopy and 4D-tracking ENB were performed in one procedure session under general anesthesia, with the procedure order being randomly assigned. Radial probe endobronchial ultrasound and fluoroscopy were used in both groups. The diagnostic performance, safety, total procedure time, and total fluoroscopy time of the ENB phase were compared to the corresponding conventional bronchoscopy phase.

Results

The study was terminated due to poor accrual; a total of eleven patients were enrolled. The mean size of pulmonary nodules was 2.1 cm. The sensitivity for malignancy was 67% (6/9) and 56% (5/9) with conventional bronchoscopy and with 4D-tracking ENB, respectively. Two cases developed minor bleeding after conventional bronchoscopy, while no complications were observed after 4D-tracking ENB. The mean procedure time was 16.1 and 21.7 min (P=0.090), and the mean duration time for fluoroscopy use was 77 and 44 sec (P=0.056) for the conventional bronchoscopy and the 4D-tracking ENB phases, respectively.

Conclusions

The diagnostic performance of the Veran SPiNDrive 4D-tracking ENB did not exceed that of conventional bronchoscopy for pulmonary nodules. No complications were seen during 4D-tracking ENB. A study with a larger number of participants is required for further assessment.

Bronchoscopic Diagnostic Procedures Available to the Pulmonologist

In the diagnosis of lung cancer, pulmonologists have several tools at their disposal. From the tried and true convex probe endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration to robotic bronchoscopy for peripheral lesions and new technology to unblind the biopsy tools, this article elucidates and expounds on the tools currently available and being developed for lung cancer diagnosis.

Feasibility of manual bronchial branch reading technique in navigating conventional rEBUS bronchoscopy in the evaluation of peripheral pulmonary lesion

BACKGROUND

Although radial endobronchial ultrasound (rEBUS) is an important verification tool in guided bronchoscopy, a navigational route was not provided. Manual airway mapping allows the bronchoscopist to translate the bronchial branching in computed tomography (CT) into a comparable bronchoscopic road map. We aimed to explore the feasibility of this technique in navigating conventional rEBUS bronchoscopy in the localisation of peripheral pulmonary lesion by determining navigation success and diagnostic yield.

METHODS

Retrospective review of consecutive rEBUS bronchoscopy performed with a 6.2 mm conventional bronchoscope navigated via manual bronchial branch reading technique over 18 months.

RESULTS

Ninety-eight target lesions were included. Median lesion size was 2.67 cm (IQR 2.22-3.38) with 96.9% demonstrating positive CT bronchus sign. Majority (86.7%) of lesions were situated in between the third and fifth airway generations. Procedure was performed with endotracheal intubation in 43.9% and fluoroscopy in 72.4%. 98.9% of lesions were successfully navigated and verified by rEBUS following the pre-planned airway road map. Bidirectional guiding device was employed in 29.6% of cases. Clinical diagnosis was secured in 88.8% of cases, majority of which were malignant disease. The discrepancy between navigation success and diagnostic yield was 10.1%. Target PPL located within five airway generations was associated with better diagnostic yield (95.1% vs. 58.8%, P < 0.001). There was 1 (1.0%) pneumothorax in our cohort.

CONCLUSIONS

Manual bronchial branch reading technique in combination with conventional rEBUS is feasible in localisation of PPL, especially for lesions located within the first five airway generations.

The value of navigation bronchoscopy in the diagnosis of peripheral pulmonary lesions: A meta-analysis

Background

To compare the diagnostic yield of peripheral pulmonary lesions (PPLs) with and without navigation system.

Methods

Studies dating from January 1990 to October 2019 were collected from databases. Diagnostic yield of navigation bronchoscopy and non‐navigation bronchoscopy was extracted from comparative studies. Subgroup analysis was adopted to test diagnostic yield variation by lesion size, lobe location of the lesion, distance from the hilum, bronchus sign and nature of the lesion.

Results

In total, 2131 patients from 10 studies were enrolled into the study. Diagnostic yield of navigation bronchoscopy was statistically higher than non‐navigation bronchoscopy for PPLs (odds ratio [OR] 1.69, 95% confidence interval [CI] 1.32, 2.18, P < 0.001), particularly for PPLs in the peripheral third lung (OR 2.26, 95% CI 1.48, 3.44, P < 0.001) and for bronchus sign positive PPLs (OR 2.26, 95% CI 1.21, 4.26, P = 0.011). Navigation bronchoscopy had better performance than non‐navigation bronchoscopy when PPLs were ≤ 20 mm (OR 2.09, 95% CI 1.44, 3.03, P < 0.001). It also elevated diagnostic yield of malignant PPLs (OR 1.67, 95% CI 1.26, 2.22, P < 0.001) and PPLs in the bilateral upper lobes (OR 1.50, 95% CI 1.09, 2.08, P = 0.014).

Conclusions

Navigation bronchoscopy enhanced diagnostic yield when compared to non‐navigation bronchoscopy, particularly for PPLs in the peripheral third lung, PPLs being bronchus sign positive, PPLs ≤ 20 mm, malignant PPLs and PPLs in the bilateral upper lobes.

Key points

The current study provided systematic evaluation on the diagnostic value of navigation bronchoscopy by comparing it with non‐navigation bronchoscopy, and exploring the factors affecting the diagnostic yield.

Segmentation of distal airways using structural analysis

Segmentation of airways in Computed Tomography (CT) scans is a must for accurate support of diagnosis and intervention of many pulmonary disorders. In particular, lung cancer diagnosis would benefit from segmentations reaching most distal airways. We present a method that combines descriptors of bronchi local appearance and graph global structural analysis to fine-tune thresholds on the descriptors adapted for each bronchial level. We have compared our method to the top performers of the EXACT09 challenge and to a commercial software for biopsy planning evaluated in an own-collected data-base of high resolution CT scans acquired under different breathing conditions. Results on EXACT09 data show that our method provides a high leakage reduction with minimum loss in airway detection. Results on our data-base show the reliability across varying breathing conditions and a competitive performance for biopsy planning compared to a commercial solution.

Navigation Bronchoscopy

With the advent of lung cancer screening, and the increasingly frequent use of computed tomography (CT) scanning for investigating non-pulmonary pathology (for example CT coronary angiogram), the number of pulmonary nodules requiring further investigation has risen significantly. Most of these nodules are found in the lung periphery, which presents challenges to biopsy, and many centers rely on trans-thoracic needle biopsy performed under image guidance by radiologists. However, the desire to minimize complications is driving the development of increasingly accurate navigation bronchoscopy platforms, something that will be crucial in the new era of bronchoscopic therapeutics for lung cancer. This review describes these platforms, summarizes the current evidence for their use, and takes a look at future developments.

Advances in interventional diagnostic bronchoscopy for peripheral pulmonary lesions

Introduction: The incidence of peripheral pulmonary lesions (PPLs) is growing following the adoption of lung cancer screening by low-dose chest CT. Although CT-guided transthoracic needle aspiration has been the standard method to diagnose PPLs, the field of interventional bronchoscopy is rapidly advancing to overcome complications of the transthoracic approach yet maintain the yield. Areas covered: This article reviews the clinical evidence of recent emerging interventional bronchoscopic techniques for diagnosis of PPLs. Expert opinion: Recent advances in interventional bronchoscopy contribute to not only the safety of transbronchial approaches to PPLs but also the higher diagnostic yield. To perform accurate sampling of PPLs, bronchoscopists must select the correct airway, approach the target as close as possible, and confirm the location of the target before sampling. These key steps can be assisted by recently developed technologies. However, it is important for bronchoscopists to understand the strengths and limitations of these emerging technologies.

Diagnostic Yield of the Virtual Bronchoscopic Navigation System Guided Sampling of Peripheral Lung Lesions using Ultrathin Bronchoscope and Protected Bronchial Brush

OBJECTIVES

The use of an ultrathin bronchoscope (UB) to diagnose peripheral pulmonary lesions is described. A virtual bronchoscopic navigation system was used to direct the ultrathin scope to the nodule. One of the constraints of this technique was the inability to confirm the target lesion position during biopsy by using a conventional linear endobronchial ultrasound probe, since the probe does not fit into a 1.2 mm working channel of this bronchoscope. The aim of the study was to review our institutional experience with the use of a UB for sampling peripheral pulmonary lesions using the transbronchial brush guided by virtual bronchoscopy. We describe a technique wherein we attempt to brush all the visible bronchial sub-segments once the bronchoscope has reached close to the nodule.

MATERIALS AND METHODS

In total, 52 patients underwent the procedure between 2010 and 2017. A multiplanar computed tomography (CT) scan of the chest was obtained and subsequently uploaded to the Lung Point Virtual bronchoscopy navigation software. The UB was parked close to the lesion. All visible airway branches were then brushed using a protected bronchial brush. The data were retrospectively abstracted from the electronic medical records using standardized forms.

RESULTS

A total of 52 lesions (40 solid, 8 part-solid, 3 cavitary, and 1 ground-glass) were sampled using a transbronchial brush (median, 2; range, 1-8). Twenty-four lesions were under 2 cm in size. The overall success rates were 67.3%. The average diameter of nodules was 2.7±1.01 cm; 65% lesions were in the outer-third of the lungs. The cancer-specific sensitivity was 72.5%. The presence of bronchus sign; location of the lesion; and the characteristics, size, and stage of cancer did not have any impact on the diagnostic yield.

CONCLUSION

Virtual bronchoscopy-guided ultrathin bronchoscopy with bronchial brushing is safe and has a diagnostic yield comparable to other described techniques for evaluating peripheral pulmonary nodules.

Radial probe endobronchial ultrasound assisted conventional transbronchial needle aspiration in the diagnosis of solitary peribronchial pulmonary lesion located in the segmental bronchi

Background: The diagnosis of peribronchial pulmonary lesions located in the tertiary bronchi, also known as segmental bronchi, as well as, the 4th order and 5th order segmental bronchi is very difficult. Histopathological specimens cannot be easily obtained by endobronchial biopsies (EBBX) due to the patent but small segmental bronchial lumen. The aim of the present study was to evaluate the diagnostic accuracy and safety of the novel technique with radial probe endobronchial ultrasound (R-EBUS) assisted conventional transbronchial needle aspiration (C-TBNA) in the diagnosis of solitary peribronchial pulmonary lesions located in segmental bronchi from 3th to 5th order. Methods: From December 2014 to December 2015, 16 patients with solitary peribronchial pulmonary lesions in the segmental bronchi from 3th to 5th order confirmed by computed tomography (CT) were enrolled. The lesions were located using radial probe endobronchial ultrasound (R-EBUS) to determine the sites of conventional transbronchial needle aspiration (C-TBNA), then, histopathological specimens were obtained using the technique of C-TBNA. The final pathological diagnosis was made based on the findings from the surgical specimens. Statistical analyses were performed for specimen results and complications. Results: On pathological evaluation, 14 of the 16 specimens were malignant, including 8 adenocarcinomas, 4 squamous cell carcinomas, and 2 small cell carcinomas, while 2 were non-malignant diseases. The diagnostic accuracy rate, sensitivity and missed diagnosis rates were 87.5%, 87.5% and 12.5%, respectively. When Combined the results of cytology with histologic samples obtained from C-TBNA the total diagnostic accuracy rate, sensitivity and missed diagnosis rate were 93.75%, 93.75% and 6.25%, respectively. There were 2 cases of bleeding complications >5 mL after C-TBNA, and both were resolved with endobronchial management. Conclusions: The combination of R-EBUS with C-TBNA was advantageous and safe for the diagnosis of solitary peribronchial pulmonary lesions located in the segmental bronchi. However, possible bleeding complications should be anticipated with needle aspiration. Further verification of this combined application should be investigated in larger clinical trials.

Competence in navigation and guided transbronchial biopsy for peripheral pulmonary lesions

Options for non-surgical tissue diagnosis of the peripheral nodule include CT scan-guided TTNA, fluoroscopy-guided bronchoscopy, radial endobronchial ultrasound (EBUS), electromagnetic navigation bronchoscopy (ENB), and virtual bronchoscopy navigation (VBN). For physicians who choose to pursue non-surgical biopsy, the decision to perform CT scan-guided or ultrasound-guided TTNA, conventional bronchoscopy or bronchoscopy guided by EBUS, ENB, or VBN will depend on a number of factors. CT scan-guided TTNA is preferable for nodules located near the chest wall or for deeper lesions, provided that there is no need to go through the fissures and there is no surrounding emphysema. Ultrasound-guided TTNA requires contact between the lesion and the costal pleura. Bronchoscopic techniques are preferable for nodules ≥2 cm located near a patent bronchus, or in individuals at high risk for pneumothorax following TTNA. In most other situations, operator experience should guide the decision. Trainees must possess a perfect knowledge of anatomy and be fully competent in the interpretation of imaging (CT with contrast medium and PET) and have a thorough knowledge of navigation technology in all its complexities. Practical training can be performed on animal, cadaver or plastic models. In the last years, to improve diagnostic yield, navigational bronchoscopy has attracted significant attention.

The Direct Oblique Method: A New Gold Standard for Bronchoscopic Navigation That is Superior to Automatic Methods

BACKGROUND

The purpose of this study was to identify bronchi on computed tomographic (CT) images, manual analysis is more accurate than automatic methods. Nonetheless, manual bronchoscopic navigation is not preferred as it involves mentally reconstructing a route to a bronchial target by interpreting 2-dimensional CT images. Here, we established the direct oblique method (DOM), a form of manual bronchoscopic navigation that does not necessitate mental reconstruction, and compared it with automatic virtual bronchoscopic navigation (VBN).

METHODS

Routes were calculated to 47 identical targets using 2 automatic VBNs (LungPoint and VINCENT-BFsim) and the DOM, using 3 general application CT viewers (Aquarius, Synapse Vincent, and OsiriX). Results of all analyses were compared.

RESULTS

The DOM drew routes to more targets than the VBNs [94% (the DOM on any viewer) vs. 49% (LungPoint) vs. 62% (VINCENT-BFsim), P<0.0001]. For the 44 targets with the CT-bronchus or CT-artery signs, 100% of the DOM routes led to targets. In the bronchoscopic simulation phase, the DOM covered 100% of the bifurcations identified on CT, whereas some bifurcations were skipped and some bronchial walls appeared partially transparent in the VBNs. Manual analysis identified more bronchi near the targets than the VBNs [32.1±3.4 (manual analysis) vs.18.9±2.1 (LungPoint) vs. 22.9±2.7 (VINCENT-BFsim), mean±SEM, P<0.0001]. The DOM took around 5 minutes on average.

CONCLUSION

On the basis of precise manual CT analysis using general application CT viewers, the DOM drew routes leading to more targets and provided better bronchoscopic simulation than the automatic route calculation of the VBNs.

Bronchoscopy for the diagnosis of peripheral lung lesions

Peripheral pulmonary lesions (PPLs) are generally considered as lesions in the peripheral one-third of the lung although a precise definition and radiographic anatomical landmarks separating central and peripheral lesion does not yet exist. The radiographic detection of such lesions has increased significantly with the adoption of lung cancer screening programs. These lesions are not directly visible by regular flexible bronchoscopes as they are usually distal to the lobar and segmental bronchi. Traditionally, depending on location and clinical stage at presentation, these lesions were typically sampled by computerized tomography (CT) guided needle or surgical biopsy although some centers also used ultrasound and fluoroscopy guided percutaneous needle biopsy. Due to lack of direct visualization, the yield for bronchoscopic guided sampling especially of the small <2 cm pulmonary nodules was very low. Therefore, sampling has been preferentially performed by percutaneous CT guidance, which had high yield of above 90% but it comes at the cost of higher risk complications like pneumothorax with reported rate of 15% to 28%. Directly proceeding to surgical resection is also considered in appropriate candidates with high suspicion of malignancy without any evidence of distant metastasis but the proportion of such cases of lung cancer is low. The manuscript discussed the various bronchoscopic diagnostic modalities for peripheral pulmonary lesions. It is important to note that most of the studies in this field are relatively small, not randomized, suffer from selection bias, have considerable heterogeneity in sampling methodology/instruments and usually have been performed in high volume institutions by dedicated highly experienced proceduralists. The prevalence of malignancy in most of the reported cohorts has also been high which may result in higher diagnostic yields. All these factors need to be kept in mind before generalizing the results to individual centers and practices.

Role of electromagnetic navigational bronchoscopy in pulmonary nodule management

The incidence of pulmonary nodules and lung cancer is rising. Some of this increase in incidence is due to improved pick up by newer imaging modalities. However, the goal is to diagnose these lesion, many of which are located in the periphery, by safe and relatively non-invasive methods. This has led to the emergence of numerous techniques such as electromagnetic navigational bronchoscopy (ENB). Current evidence supports a role for these techniques in the diagnostic pathway. However, numerous factor influence the diagnostic accuracy. Thus despite significant advances, more research needs to be undertaken to further improve the currently available diagnostic technologies.

Navigational Bronchoscopy for Early Lung Cancer: A Road to Therapy

Peripheral lung nodules remain challenging for accurate localization and diagnosis. Once identified, there are many strategies for diagnosis with heterogeneous risk benefit analysis. Traditional strategies such as conventional bronchoscopy have poor performance in locating and acquiring the required tissue. Similarly, while computerized-assisted transthoracic needle biopsy is currently the favored diagnostic procedure, it is associated with complications such as pneumothorax and hemorrhage. Video-assisted thoracoscopic and open surgical biopsies are invasive, require general anesthesia and are therefore not a first-line approach. New techniques such as ultrathin bronchoscopy and image-based guidance technologies are evolving to improve the diagnosis of peripheral lung lesions. Virtual bronchoscopy and electromagnetic navigation systems are novel technologies based on assisted-computerized tomography images that guide the bronchoscopist toward the target peripheral lesion. This article provides a comprehensive review of these emerging technologies.

Improvements to bronchoscopic brushing with a manual mapping method: A three-year experience of 1143 cases

Background

Conventional bronchoscopy with brushing alone for diagnosing peripheral pulmonary lesions (PPLs) is of low sensitivity. A manual mapping method was introduced and evaluated in this study, which could be routinely applied with bronchoscopic brushing to improve the sensitivity for malignant PPLs.

Methods

This mapping method involves the bronchoscopist drawing the route with a series of bronchial opening sketches and marking the leading bronchus at every bifurcation point based on thin‐section computed tomography. This map is then used to guide bronchoscope insertion for brushing. A cross‐sectional study on the evaluation of this method for the diagnosis of malignant PPLs was conducted on patients from July 2010 to June 2013.

Results

The sensitivity for malignant PPLs of conventional brushing, conventional brushing with mapping on a portion of patients, and conventional brushing with mapping method increased from 17.0% to 25.8% to 31.5% (P < 0.001), respectively. For lesion sizes over 3 cm, the rate of these three groups increased from 25.1% to 38.6% to 50.9% (P < 0.001), respectively. The sensitivity of this mapping method for malignant PPLs was statistically associated with lesion size, lesion character, relationship between the lesion and the leading bronchus, linear distance between the targeted bronchus and the opening of the lobe bronchus, and accessibility (P < 0.001, P = 0.039, P < 0.001, P = 0.031, and P = 0.020, respectively).

Conclusions

The manual mapping method greatly increased the bronchoscopic brushing sensitivity for malignant PPLs compared to the conventional brushing method. During routine clinical work, it is economical and convenient for guiding bronchoscope insertion.

Hands-Free System for Bronchoscopy Planning and Guidance

Bronchoscopy is a commonly used minimally invasive procedure for lung-cancer staging. In standard practice, however, physicians differ greatly in their levels of performance. To address this concern, image-guided intervention (IGI) systems have been devised to improve procedure success. Current IGI bronchoscopy systems based on virtual bronchoscopic navigation (VBN), however, require involvement from the attending technician. This lessens physician control and hinders the overall acceptance of such systems. We propose a hands-free VBN system for planning and guiding bronchoscopy. The system introduces two major contributions. First, it incorporates a new procedure-planning method that automatically computes airway navigation plans conforming to the physician's bronchoscopy training and manual dexterity. Second, it incorporates a guidance strategy for bronchoscope navigation that enables user-friendly system control via a foot switch, coupled with a novel position-verification mechanism. Phantom studies verified that the system enables smooth operation under physician control, while also enabling faster navigation than an existing technician-assisted VBN system. In a clinical human study, we noted a 97% bronchoscopy navigation success rate, in line with existing VBN systems, and a mean guidance time per diagnostic site = 52 s. This represents a guidance time often nearly 3 min faster per diagnostic site than guidance times reported for other technician-assisted VBN systems. Finally, an ergonomic study further asserts the system's acceptability to the physician and long-term potential.

Virtual bronchoscopic navigation for peripheral pulmonary lesions

Virtual bronchoscopic navigation (VBN) is a method in which the bronchoscope is guided on the bronchial route to a peripheral lesion using virtual bronchoscopic images. In reports on VBN for peripheral pulmonary lesions searched in PubMed as of November 2013, the diagnostic yield by ultrathin bronchoscopy in combination with computed tomography and VBN was within the range of 65.4-81.6%. Using endobronchial ultrasonography with a guide sheath (EBUS-GS) and VBN, it was between 63.3 and 84.4%, and using X-ray fluoroscopy and VBN, it was between 62.5 and 78.7%. The overall diagnostic yield was 73.8% [95% confidence interval (CI) 70.9-76.8%] and that for lesions ≤ 2 cm was 67.4% (95% CI 63.3-71.5%). These values indicate high diagnostic rates. In randomized comparative trials, the combination of VBN with EBUS-GS improved the diagnostic yield and shortened the examination time. The diagnostic yields for lesions in the right upper lobe, those invisible on posterior-anterior radiographs and those located in the peripheral third of the lung field were improved by VBN on ultrathin bronchoscopy in combination with X-ray fluoroscopy. The usefulness of VBN was also found on meta-analysis. Taken together, VBN is a promising navigational bronchoscopy method as it requires no specific training, has a low overall complication rate of 1.0% (95% CI 0.2-1.8%) and does not directly induce or cause severe complications. To maximize the full potential of VBN and promote its use, investigation of cases in which it is useful, determination of the optimum combination of procedures, a cost/benefit analysis and advancement of the VBN system are warranted.

Novel bronchoscopic strategies for the diagnosis of peripheral lung lesions: present techniques and future directions

The diagnosis of the peripheral lung lesion has been a long-standing clinical challenge--balancing accuracy with patient safety. With recent data revealing mortality benefits with lung cancer screening via low-dose computed tomography, now more than ever, clinicians will be challenged with the task of providing the means to provide a safe and minimally invasive method of obtaining accurate tissue diagnostics for the pulmonary nodule. In this review, we present available technologies to aid clinicians in attempts at minimally invasive techniques and the data supporting their use. In addition, we review novel tools under investigation that may further increase yield and provide additional benefit in obtaining an early diagnosis of lung cancer.

Diagnostic bronchoscopy--current and future perspectives

Lung cancer is the leading cause of cancer-related mortality worldwide. Standard bronchoscopy has limited ability to accurately localise and biopsy pulmonary lesions that cannot be directly visualised. The field of advanced diagnostic bronchoscopy is rapidly evolving due to advances in electronics and miniaturisation. Bronchoscopes with smaller outer working diameters, coupled with miniature radial and convex ultrasound probes, allow accurate central and peripheral pulmonary lesion localisation and biopsy while at the same time avoiding vascular structures. Increases in computational processing power allow three-dimensional reconstruction of computed tomographic raw data to enable virtual bronchoscopy (VB), providing the bronchoscopist with a preview of the bronchoscopy prior to the procedure. Navigational bronchoscopy enables targeting of peripheral pulmonary lesions (PPLs) via a "roadmap", similar to in-car global positioning systems. Analysis of lesions on a cellular level is now possible with techniques such as optical coherence tomography (OCT) and confocal microscopy (CM). All these tools will hopefully allow earlier and safer lung cancer diagnosis and in turn better patient outcomes. This article describes these new bronchoscopic techniques and reviews the relevant literature.

Optimal procedure planning and guidance system for peripheral bronchoscopy

With the development of multidetector computed-tomography (MDCT) scanners and ultrathin bronchoscopes, the use of bronchoscopy for diagnosing peripheral lung-cancer nodules is becoming a viable option. The work flow for assessing lung cancer consists of two phases: 1) 3-D MDCT analysis and 2) live bronchoscopy. Unfortunately, the yield rates for peripheral bronchoscopy have been reported to be as low as 14%, and bronchoscopy performance varies considerably between physicians. Recently, proposed image-guided systems have shown promise for assisting with peripheral bronchoscopy. Yet, MDCT-based route planning to target sites has relied on tedious error-prone techniques. In addition, route planning tends not to incorporate known anatomical, device, and procedural constraints that impact a feasible route. Finally, existing systems do not effectively integrate MDCT-derived route information into the live guidance process. We propose a system that incorporates an automatic optimal route-planning method, which integrates known route constraints. Furthermore, our system offers a natural translation of the MDCT-based route plan into the live guidance strategy via MDCT/video data fusion. An image-based study demonstrates the route-planning method's functionality. Next, we present a prospective lung-cancer patient study in which our system achieved a successful navigation rate of 91% to target sites. Furthermore, when compared to a competing commercial system, our system enabled bronchoscopy over two airways deeper into the airway-tree periphery with a sample time that was nearly 2 min shorter on average. Finally, our system's ability to almost perfectly predict the depth of a bronchoscope's navigable route in advance represents a substantial benefit of optimal route planning.

Interactive CT-video registration for the continuous guidance of bronchoscopy

Bronchoscopy is a major step in lung cancer staging. To perform bronchoscopy, the physician uses a procedure plan, derived from a patient's 3D computed-tomography (CT) chest scan, to navigate the bronchoscope through the lung airways. Unfortunately, physicians vary greatly in their ability to perform bronchoscopy. As a result, image-guided bronchoscopy systems, drawing upon the concept of CT-based virtual bronchoscopy (VB), have been proposed. These systems attempt to register the bronchoscope's live position within the chest to a CT-based virtual chest space. Recent methods, which register the bronchoscopic video to CT-based endoluminal airway renderings, show promise but do not enable continuous real-time guidance. We present a CT-video registration method inspired by computer-vision innovations in the fields of image alignment and image-based rendering. In particular, motivated by the Lucas-Kanade algorithm, we propose an inverse-compositional framework built around a gradient-based optimization procedure. We next propose an implementation of the framework suitable for image-guided bronchoscopy. Laboratory tests, involving both single frames and continuous video sequences, demonstrate the robustness and accuracy of the method. Benchmark timing tests indicate that the method can run continuously at 300 frames/s, well beyond the real-time bronchoscopic video rate of 30 frames/s. This compares extremely favorably to the ≥ 1 s/frame speeds of other methods and indicates the method's potential for real-time continuous registration. A human phantom study confirms the method's efficacy for real-time guidance in a controlled setting, and, hence, points the way toward the first interactive CT-video registration approach for image-guided bronchoscopy. Along this line, we demonstrate the method's efficacy in a complete guidance system by presenting a clinical study involving lung cancer patients.

Computer-based route-definition system for peripheral bronchoscopy

Multi-detector computed tomography (MDCT) scanners produce high-resolution images of the chest. Given a patient's MDCT scan, a physician can use an image-guided intervention system to first plan and later perform bronchoscopy to diagnostic sites situated deep in the lung periphery. An accurate definition of complete routes through the airway tree leading to the diagnostic sites, however, is vital for avoiding navigation errors during image-guided bronchoscopy. We present a system for the robust definition of complete airway routes suitable for image-guided bronchoscopy. The system incorporates both automatic and semiautomatic MDCT analysis methods for this purpose. Using an intuitive graphical user interface, the user invokes automatic analysis on a patient's MDCT scan to produce a series of preliminary routes. Next, the user visually inspects each route and quickly corrects the observed route defects using the built-in semiautomatic methods. Application of the system to a human study for the planning and guidance of peripheral bronchoscopy demonstrates the efficacy of the system.

Virtual bronchoscopy-guided transbronchial biopsy for aiding the diagnosis of peripheral lung cancer

OBJECTIVE

The aim of this study was to evaluate the clinical value of virtual bronchoscopy (VB) in aiding diagnosis of peripheral lung cancer by transbronchial biopsy (TBB). In addition, we sought to systematically analyze the factors that affect the diagnostic sensitivity of VB-guided TBB for the evaluation of peripheral lung cancers.

MATERIALS AND METHODS

A hundred and twenty-two peripheral lung cancers from 122 patients (82 men and 40 women, 38-84 years; median 68.5 years) who were performed VB-guided TBB were evaluated retrospectively. VB was reconstructed from 1- or 0.5-mm slice thickness images of multi-detector CT (MDCT). Experienced pulmonologists inserted the conventional and ultrathin bronchoscopes into the target bronchus under direct vision following the VB image.

RESULTS

A definitive diagnosis was established by VB-guided TBB in 96 lesions (79%). The diagnostic sensitivity of small pulmonary lesions ≤30 mm in maximal diameter (71%) was significantly lower than that of lesions >30 mm (91%, p=0.008). For small pulmonary lesions ≤30 mm (n=76), internal opacity of the lesion was the independent predictor of diagnostic sensitivity by VB-guided TBB, and the non-solid type lung cancers were significantly lower than the solid type and part-solid type lung cancers for diagnostic sensitivity (odds ratio=0.161; 95% confidence interval=0.033-0.780; p=0.023).

CONCLUSION

Use of an ultrathin bronchoscope and simulation with VB reconstructed by high quality MDCT images is thought to improve pathological diagnosis of peripheral lung cancers, especially for solid and partly solid types. For small pulmonary lesions ≤30 mm, the lesion internal opacity is a significant factor for predicting the diagnostic sensitivity, and the sensitivity was low for small non-solid type of lung cancers.

3D MDCT-based system for planning peripheral bronchoscopic procedures

The diagnosis and staging of lung cancer often begins with the assessment of a suspect peripheral chest site. Such suspicious peripheral sites may be solitary pulmonary nodules or other abnormally appearing regions of interest (ROIs). The state-of-the-art process for assessing such peripheral ROIs involves off-line procedure planning using a three-dimensional (3D) multidetector computed tomography (MDCT) chest scan followed by bronchoscopy with an ultrathin bronchoscope. We present an integrated computer-based system for planning peripheral bronchoscopic procedures. The system takes a 3D MDCT chest image as input and performs nearly all operations automatically. The only interaction required by the physician is the selection of ROI locations. The system is computationally efficient and fits smoothly within the clinical work flow. Integrated into the system and described in detail in the paper is a new surface-definition method, which is vital for effective analysis and planning to peripheral sites. Results demonstrate the efficacy of the system and its usage for the live guidance of ultrathin bronchoscopy to the periphery.

Image-based reporting for bronchoscopy

Bronchoscopy is often performed for staging lung cancer. The recent development of multidetector computed tomography (MDCT) scanners and ultrathin bronchoscopes now enable the bronchoscopic biopsy and treatment of peripheral diagnostic regions of interest (ROIs). Because these ROIs are often located several generations within the airway tree, careful planning and interpretation of the bronchoscopic route is required prior to a procedure. The current practice for planning bronchoscopic procedures, however, is difficult, error prone, and time consuming. To alleviate these issues, we propose a method for producing and previewing reports for bronchoscopic procedures using patient-specific MDCT chest scans. The reports provide quantitative data about the bronchoscopic routes and both static and dynamic previews of the proper airway route. The previews consist of virtual bronchoscopic endoluminal renderings along the route and three-dimensional cues for a final biopsy site. The reports require little storage space and computational resources, enabling physicians to view the reports on a portable tablet PC. To evaluate the efficacy of the reporting system, we have generated reports for 22 patients in a human lung cancer patient pilot study. For 17 of these patients, we used the reports in conjunction with live image-based bronchoscopic guidance to direct physicians to central chest and peripheral ROIs for subsequent diagnostic evaluation. Our experience shows that the tool enabled useful procedure preview and an effective means for planning strategy prior to a live bronchoscopy.