Virtual bronchoscopic navigation system shortens the examination time—Feasibility study of virtual bronchoscopic navigation system

Ultrathin bronchoscopy for diagnosing peripheral pulmonary lesions

Bronchoscopes are continuously improving. Increasingly, thinner bronchoscopes with larger working channels and better imaging quality are becoming available for clinical use. Concurrently, useful ancillary devices have been developed, such as radial probe endobronchial ultrasound (rEBUS) and navigation devices. Randomized studies have demonstrated the diagnostic superiority of ultrathin bronchoscopy over thin bronchoscopy under rEBUS and virtual bronchoscopic navigation guidance for small, peripheral pulmonary lesions. Furthermore, biopsy needles and cryoprobes have been miniaturized and adapted to the working channel of the new ultrathin bronchoscopes. Multi-modality and multi-instrumental ultrathin bronchoscopy using such new technologies has facilitated high diagnostic yields.

Guided Bronchoscopy for the Evaluation of Pulmonary Lesions: An Updated Meta-analysis

BACKGROUND

Guided bronchoscopy is increasingly used to diagnose peripheral pulmonary lesions (PPLs). A meta-analysis published in 2012 demonstrated a pooled diagnostic yield of 70%; however, recent publications have documented yields as low as 40% and as high as 90%.

RESEARCH QUESTION

Has the diagnostic yield of guided bronchoscopy in patients with PPLs improved over the past decade?

STUDY DESIGN AND METHODS

A comprehensive search was performed of studies evaluating the diagnostic yield of differing bronchoscopic technologies used to reach PPLs. Study quality was assessed using the Quality assessment of diagnostic accuracy of studies (QUADAS-2) assessment tool. Number of lesions, type of technology used, overall diagnostic yield, and yield by size were extracted. Adverse events were recorded. Meta-analytic techniques were used to summarize findings across all studies.

RESULTS

A total of 16,389 lesions from 126 studies were included. There was no significant difference in diagnostic yield prior to 2012 (39 studies; 3,052 lesions; yield 70.5%) vs after 2012 (87 studies; 13,535 lesions; yield 69.2%) (P > .05). Additionally, there was no significant difference in yield when comparing different technologies. Studies with low risk of overall bias had a lower diagnostic yield than those with high risk of bias (66% vs 71%, respectively; P = .018). Lesion size > 2 cm, presence of bronchus sign, and reports with a high prevalence of malignancy in the study population were associated with significantly higher diagnostic yield. Significant (P < .0001) between-study heterogeneity was also noted.

INTERPRETATION

Despite the reported advances in bronchoscopic technology to diagnose PPLs, the diagnostic yield of guided bronchoscopy has not improved.

Advancements in navigational bronchoscopy for peripheral pulmonary lesions: A review with special focus on virtual bronchoscopic navigation

Lung cancer is often diagnosed at an advanced stage and is associated with significant morbidity and mortality. Low-dose computed tomography for lung cancer screening has increased the incidence of peripheral pulmonary lesions. Surveillance and early detection of these lesions at risk of developing cancer are critical for improving patient survival. Because these lesions are usually distal to the lobar and segmental bronchi, they are not directly visible with standard flexible bronchoscopes resulting in low diagnostic yield for small lesions <2 cm. The past 30 years have seen several paradigm shifts in diagnostic bronchoscopy. Recent technological advances in navigation bronchoscopy combined with other modalities have enabled sampling lesions beyond central airways. However, smaller peripheral lesions remain challenging for bronchoscopic biopsy. This review provides an overview of recent advances in interventional bronchoscopy in the screening, diagnosis, and treatment of peripheral pulmonary lesions, with a particular focus on virtual bronchoscopic navigation.

Diagnostic value of ultrathin bronchoscopy in peripheral pulmonary lesions: a narrative review

Flexible bronchoscopes are being continuously improved, and an ultrathin bronchoscope with a working channel that allows the use of a radial-type endobronchial ultrasound (EBUS) probe is now available. The ultrathin bronchoscope has good maneuverability for passing through the small bronchi and good accessibility to peripheral lung lesions. This utility is particularly enhanced when it is used with other imaging devices, such as EBUS and navigation devices. Multimodality bronchoscopy using an ultrathin bronchoscope leads to enhanced diagnostic yield.

Technologies for targeting the peripheral pulmonary nodule including robotics

Bronchoscopic sampling of PPL was significantly advanced by the development of the endobronchial ultrasound guide sheath method in the 1990s. Since then, a range of technical and procedural techniques have further advanced diagnostic yields. These include the use of thinner bronchoscopes with better working channel diameters, understanding the importance of peripheral transbronchial needle aspiration, and virtual bronchoscopic assistance. These have enabled better sampling of smaller and more technically challenging lesions including ground-glass nodules. Most recently, robotic bronchoscopy has been developed which, among other refinements, allows fine control of visual bronchoscopic navigation by replacing movements directed by the hand with electronic consoles and trackballs, and innovatively integrate virtual with real bronchoscopic pathways. The requirement for PPL diagnosis and treatment is expected to increase with more chest CT performed as part of CT screening programmes.

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.

Virtual bronchoscopic navigation without X-ray fluoroscopy to diagnose peripheral pulmonary lesions: a randomized trial

Background

Transbronchial biopsy for peripheral pulmonary lesions is generally performed under X-ray fluoroscopy. Virtual bronchoscopic navigation (VBN) is a method in which virtual images of the bronchial route to the lesion are produced based on CT images obtained before VBN, and the bronchoscope is guided using these virtual images, improving the diagnostic yield of peripheral pulmonary lesions. VBN has the possibility of eliminating the need for X-ray fluoroscopy in the bronchoscopic diagnosis of peripheral lesions. To determine whether VBN can be a substitute for X-ray fluoroscopy, a randomized multicenter trial (non-inferiority trial) was performed in VBN and X-ray fluoroscopy (XRF) -assisted groups.

Methods

The non-inferiority margin in the VBN-assisted group compared with the XRF-assisted group was set at 15%. The subjects consisted of 140 patients with peripheral pulmonary lesions with a mean diameter > 3 cm. In the VBN-assisted group, the bronchoscope was guided to the lesion using a VBN system without X-ray fluoroscopy. In the XRF-assisted group, the same bronchoscope was guided to the lesion under X-ray fluoroscopy. Subsequently, in both groups, the lesion was visualized using endobronchial ultrasonography with a guide sheath (EBUS/GS), and biopsy was performed. In this serial procedure, X-ray fluoroscopy was not used in the VBNA group.

Results

The subjects of analysis consisted of 129 patients. The diagnostic yield was 76.9% (50/65) in the VBN-assisted group and 85.9% (55/64) in the XRF-assisted group. The difference in the diagnostic yield between the two groups was -9.0% (95% confidence interval: -22.3% ~ 4.3%). The non-inferiority of the VBN-assisted group could not be confirmed. The rate of visualizing lesions by EBUS was 95.4% (62/65) in the VBN-assisted group and 96.9% (62/64) in the XRF-assisted group, being high in both groups.

Conclusions

On EBUS/GS, a bronchoscope and biopsy instruments may be guided to the lesions using VBN without X-ray fluoroscopy, but X-ray fluoroscopy is necessary to improve the accuracy of sample collection from lesions. During transbronchial biopsy for peripheral pulmonary lesions, VBN cannot be a substitute for X-ray fluoroscopy.

Trial registration

UMIN-CTR (UMIN000001710); registered 16 February 2009.

Automated Catheter Navigation With Electromagnetic Image Guidance

This paper describes a novel method of controlling an endoscopic catheter by using an automated catheter tensioning system with the objective of providing clinicians with improved manipulation capabilities within the patient. Catheters are used in many clinical procedures to provide access to the cardiopulmonary system. Control of such catheters is performed manually by the clinicians using a handle, typically actuating a single or opposing set of pull wires. Such catheters are generally actuated in a single plane, requiring the clinician to rotate the catheter handle to navigate the system. The automation system described here allows closed-loop control of a custom bronchial catheter in tandem with an electromagnetic tracking of the catheter tip and image guidance by using a 3D Slicer. An electromechanical drive train applies tension to four pull wires to steer the catheter tip, with the applied force constantly monitored through force sensing load cells. The applied tension is controlled through a PC connected joystick. An electromagnetic sensor embedded in the catheter tip enables constant real-time position tracking, whereas a working channel provides a route for endoscopic instruments. The system is demonstrated and tested in both a breathing lung model and a preclinical animal study. Navigation to predefined targets in the subject's airways by using the joystick while using virtual image guidance and electromagnetic tracking was demonstrated. Average targeting times were 29 and 10 s, respectively, for the breathing lung and live animal studies. This paper presents the first reported remote controlled bronchial working channel catheter utilizing electromagnetic tracking and has many implications for future development in endoscopic and catheter-based procedures.

Improvement in imaging diagnosis technique and modalities for solitary pulmonary nodules: from ground-glass opacity nodules to part-solid and solid nodules

With advances in CT technology and the popularity of low-dose CT as a device for lung cancer screening, the detection rate of sub-solid pulmonary nodules as well as solid nodules has been increased. Distinguishing solid from sub-solid features is an essential step in the CT evaluation of solitary pulmonary nodules (SPNs) because strategies for nodule characterization and guidelines for management are different for each category. In addition to conventional CT parameters, numerous novel concepts and modalities have been developed. Although there is currently no single effective method for differentiating malignant from benign nodules, growth rate measurement using volumetry, evaluation of tumor vascularity on dynamic helical CT, dual-energy CT and MRI and physiologic evaluation with PET/CT can all be useful for nodule characterization. New techniques such as tomosynthesis can improve detection over radiography alone. The purpose of this article is to enhance our understanding of the evidence-based strategies involved in diagnosing SPNs.

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.

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.

A three-stage method for the 3D reconstruction of the tracheobronchial tree from CT scans

This paper proposes a method for segmenting the airways from CT scans of the chest to obtain a 3D model that can be used in the virtual bronchoscopy for the exploration and the planning of paths to the lesions. The method is composed of 3 stages: a gross segmentation that reconstructs the main airway tree using adaptive region growing, a finer segmentation that identifies any potential airway region based on a 2D process that enhances bronchi walls using local information, and a final process to connect any isolated bronchus to the main airways using a morphologic reconstruction process and a path planning technique. The paper includes two examples for the evaluation and discussion of the proposal.

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.

Newer modalities in the work-up of peripheral pulmonary nodules

Technological advances in recent years have translated into the availability of newer modalities to establish the cause of peripheral pulmonary nodules (PPN). Even though the verdict is still out on the ideal diagnostic modality, there is no doubt that the bronchoscope is becoming a popular tool in the armamentarium of physicians who deal with PPN. This article focuses on newer bronchoscopic modalities being studied for the work-up of PPN. The authors also summarize the value of established diagnostic modalities to provide a balanced perspective.

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.

Meta-analysis of guided bronchoscopy for the evaluation of the pulmonary nodule

BACKGROUND

The detection of pulmonary nodules (PNs) is likely to increase, especially with the release of the National Lung Screen Trials. When tissue diagnosis is desired, transthoracic needle aspiration (TTNA) is recommended. Several guided-bronchoscopy technologies have been developed to improve the yield of transbronchial biopsy for PN diagnosis: electromagnetic navigation bronchoscopy (ENB), virtual bronchoscopy (VB), radial endobronchial ultrasound (R-EBUS), ultrathin bronchoscope, and guide sheath. We undertook this meta-analysis to determine the overall diagnostic yield of guided bronchoscopy using one or a combination of the modalities described here.

METHODS

We performed a MEDLINE search using “bronchoscopy” and “solitary pulmonary nodule.” Studies evaluating the diagnostic yield of ENB, VB, R-EBUS, ultrathin bronchoscope, and/or guide sheath for peripheral nodules were included. The overall diagnostic yield and yield based on size were extracted. Adverse events, if reported, were recorded. Meta-analysis techniques incorporating inverse variance weighting and a random-effects meta-analysis approach were used.

RESULTS

A total of 3,052 lesions from 39 studies were included. The pooled diagnostic yield was 70%, which is higher than the yield for traditional transbronchial biopsy. The yield increased as the lesion size increased. The pneumothorax rate was 1.5%, which is significantly smaller than that reported for TTNA.

CONCLUSION

This meta-analysis shows that the diagnostic yield of guided bronchoscopic techniques is better than that of traditional transbronchial biopsy. Although the yield remains lower than that of TTNA, the procedural risk is lower. Guided bronchoscopy may be an alternative or be complementary to TTNA for tissue sampling of PN, but further study is needed to determine its role in the evaluation of peripheral pulmonary lesions.

Transbronchial Biopsy for Peripheral Pulmonary Lesions Under Real-time Endobronchial Ultrasonographic Guidance

BACKGROUND AND OBJECTIVES

Transbronchial biopsy (TBB) using endobronchial ultrasonography with a guide sheath (EBUS-GS) is a promising technique for small peripheral pulmonary lesions (PPLs), but is not a real-time procedure. We attempted to examine the practicality of TBB under real-time EBUS guidance for PPLs.

METHODS

We performed TBB under real-time EBUS and x-ray fluoroscopic guidance using flexible bronchoscopy with 2 working channels for PPLs (mean diameter,>30 mm).

RESULTS

Between January 2007 and May 2007, we recruited 6 patients for this trial. On computed tomography images, the mean±SD diameter of the lesions was 37.4±4.5 mm (range: 32.0 to 45.0 mm). All lesions were detected by EBUS and could eventually be diagnosed. However, an image of the biopsy forceps or brush was obtained on real-time EBUS in only 4 cases. The other 2 cases involved technical limitations in inserting both the EBUS probe and biopsy forceps simultaneously into the lesion. Unfortunately, even in the 4 cases in which biopsy forceps images could be obtained on real-time EBUS, we could not recognize the position of the tip of the forceps on EBUS images, because the EBUS images of the tip of the forceps and the body of forceps were very similar.

CONCLUSIONS

Our attempt to perform TBB under real-time EBUS guidance for PPLs was successful in 4 of 6 patients. There were some technical limitations using flexible bronchoscopy with 2 working channels. Improvement of instruments will be necessary for future trials of TBB under real-time EBUS guidance.

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.

Robust 3-D airway tree segmentation for image-guided peripheral bronchoscopy

A vital task in the planning of peripheral bronchoscopy is the segmentation of the airway tree from a 3-D multidetector computed tomography chest scan. Unfortunately, existing methods typically do not sufficiently extract the necessary peripheral airways needed to plan a procedure. We present a robust method that draws upon both local and global information. The method begins with a conservative segmentation of the major airways. Follow-on stages then exhaustively search for additional candidate airway locations. Finally, a graph-based optimization method counterbalances both the benefit and cost of retaining candidate airway locations for the final segmentation. Results demonstrate that the proposed method typically extracts 2-3 more generations of airways than several other methods, and that the extracted airway trees enable image-guided bronchoscopy deeper into the human lung periphery than past studies.

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.

Utility of virtual bronchoscopy-guided transbronchial biopsy for the diagnosis of pulmonary sarcoidosis: report of two cases

Sarcoidosis is a multisystem granulomatous disease of unknown etiology that usually affects the lungs. Although flexible fiberoptic bronchoscopy with transbronchial lung biopsy (TBBx) has a high diagnostic yield in patients with pulmonary sarcoidosis, variously ranging from 40 to 90%, more invasive procedures often prove necessary. We report two cases of successful diagnosis of pulmonary sarcoidosis using a new technique that may increase the accuracy of TBBx. Previously described for diagnosis of peripheral lung cancer, this technique relies on real-time virtual bronchoscopic guidance to biopsy preselected peripheral areas of the lung preferentially affected by the disease using a pediatric bronchoscope. In each case, while procedures were performed under direct CT guidance allowing precise confirmation of the tip of the biopsy catheter, it is anticipated that this technique will be primarily used as a guide to bronchoscopic biopsies without the need for direct CT guidance, thus increasing routine utilization of multidetector low-dose high-resolution CT to improve histologic diagnosis.

3D CT-video fusion for image-guided bronchoscopy

Bronchoscopic biopsy of the central-chest lymph nodes is an important step for lung-cancer staging. Before bronchoscopy, the physician first visually assesses a patient's three-dimensional (3D) computed tomography (CT) chest scan to identify suspect lymph-node sites. Next, during bronchoscopy, the physician guides the bronchoscope to each desired lymph-node site. Unfortunately, the physician has no link between the 3D CT image data and the live video stream provided during bronchoscopy. Thus, the physician must essentially perform biopsy blindly, and the skill levels between different physicians differ greatly. We describe an approach that enables synergistic fusion between the 3D CT data and the bronchoscopic video. Both the integrated planning and guidance system and the internal CT-video registration and fusion methods are described. Phantom, animal, and human studies illustrate the efficacy of the methods.

American Thoracic Society Annual International Congress

The 2007 International Congress of the American Thoracic Society (ATS) was held in San Francisco, California. It is one of the most important conferences in pulmonary medicine. It provides an annual forum for scientists and clinical investigators from academia and non-university institutions including private practices and pharmaceutical companies to share information on many aspects of pulmonary and critical care medicine, sleep disorders, pulmonary infectious diseases, malignancies of the chest and numerous aspects of diagnostic and interventional procedures in that field. This year approximately 5500 abstracts were presented and approximately 15,000 participants attended the ATS congress. Research areas covered all aspects of pulmonary diseases. Traditionally obstructive pulmonary diseases (e.g., chronic obstructive pulmonary disease and asthma) were again the main focus. The general impression from the meeting was that the focus this year shifted more to basic research of pulmonary diseases, new diagnostic techniques and tools to approximate disease progression rather than presenting new drugs for treatment. Furthermore, new ATS policies for permitting industry sponsored satellite symposia - among other possible reasons - seemed to discourage pharmaceutical companies organizing such evening meetings when compared with previous ATS conferences. When up to five of such symposia used to be normal per night in previous years, just three of these sponsored sessions per night, which were labeled as 'evening postgraduate seminars', were offered at this meeting.