Multimodality Guidance for Accurate Bronchoscopic Insertion of Fiducial Markers

[The role of endoscopy in the management of peripheral pulmonary nodules, part 2: Treatment]

The management of peripheral lung nodules is challenging, requiring specialized skills and sophisticated technologies. The diagnosis now appears accessible to advanced endoscopy (see Part 1), which can also guide treatment of these nodules; this second part provides an overview of endoscopy techniques that can enhance surgical treatment through preoperative marking, and stereotactic radiotherapy treatment through fiduciary marker placement. Finally, we will discuss how, in the near future, these advanced endoscopic techniques will help to implement ablation strategy.

Biomedical advances and future prospects of high-precision three-dimensional radiotherapy and four-dimensional radiotherapy

Biomedical advances of external-beam radiotherapy (EBRT) with improvements in physical accuracy are reviewed. High-precision (±1 mm) three-dimensional radiotherapy (3DRT) can utilize respective therapeutic open doors in the tumor control probability curve and in the normal tissue complication probability curve instead of the one single therapeutic window in two-dimensional EBRT. High-precision 3DRT achieved higher tumor control and probable survival rates for patients with small peripheral lung and liver cancers. Four-dimensional radiotherapy (4DRT), which can reduce uncertainties in 3DRT due to organ motion by real-time (every 0.1-1 s) tumor-tracking and immediate (0.1-1 s) irradiation, have achieved reduced adverse effects for prostate and pancreatic tumors near the digestive tract and with similar or better tumor control. Particle beam therapy improved tumor control and probable survival for patients with large liver tumors. The clinical outcomes of locally advanced or multiple tumors located near serial-type organs can theoretically be improved further by integrating the 4DRT concept with particle beams.

Clinical Evaluation of Fiducial Marker Pre-Planning for Virtual Bronchoscopic Navigation Implantation in Lung Tumour Patients Treated With CyberKnife

Purpose

For the treatment of invisible lung tumours with CyberKnife (CK), fiducial markers (FMs) were implanted as an internal surrogate under virtual bronchoscopic navigation (VBN). This research aims to study the benefits of introducing an additional procedure in assigning the optimal FM positions using a pre-procedure planning system and performing virtual simulation before implantation. The objectives were 1) to reduce the duration of the FM implantation procedure, 2) to reduce the radiation exposure in dose area product (DAP) (dGy*cm²) to patients, and 3) to increase the number of FMs implanted around the tumour.

Methods and Materials

This study is retrospective, single-centre, and observational in nature. A total of 32 patients were divided into two groups. In Group 1, 18 patients underwent conventional VBN FM implantation. In Group 2, 14 patients underwent additional pre-procedure planning and simulation. The steps of pre-procedure planning include 1) importing CT images into the treatment planning system (Eclipse, Varian Medical Systems, Inc.) and delineating five to six FMs in their ideal virtual positions and 2) copying the FM configuration into VBN planning software (LungPoint Bronchus Medical, Inc.) for verification and simulation. Finally, the verified FMs were deployed through VBN with the guidance of the LungPoint planning software.

Results

A total of 162 FMs were implanted among 35 lesions in 32 patients aged from 37 to 92 (median = 66; 16 men and 16 women). Results showed that 1) the average FM insertion time was shortened from 41 min (SD = 2.05) to 23 min (SD = 1.25), p = 0.00; 2) the average absorbed dose of patients in DAP was decreased from 67.4 cGy*cm² (SD = 14.48) to 25.3 cGy*cm² (SD = 3.82), p = 0.01 (1-tailed); and 3) the average number of FMs implanted around the tumour was increased from 4.7 (SD = 0.84) to 5.6 (SD = 0.76), p = 0.00 (1-tailed).

Conclusion

Pre-procedure planning reduces the FM implantation duration from 41.1 to 22.9 min, reduces the radiation exposure in DAP from 67.4 to 25.3 dGy*cm², and increases the number of FMs inserted around the tumour from 4.7 to 5.6.

Fiducial markers for stereotactic lung radiation therapy: review of the transthoracic, endovascular and endobronchial approaches

Stereotactic body radiation therapy is an alternative to surgery for early-stage, inoperable peripheral non-small cell lung cancer. As opposed to linear accelerator (linac)-based (e.g. gating) and free-breathing techniques, CyberKnife® with Synchrony® technology allows accurate radiation delivery by means of a real-time respiratory motion tracking system using, in most cases, metal fiducial markers (FMs) placed in the vicinity of the target. The aims of this review are as follows. First, to describe the safety and efficacy of the transthoracic, endovascular and endobronchial FM insertion techniques for peripheral pulmonary lesions (PPLs). Second, to analyse performance in terms of the migration and tracking rates of different FM types. Recent developments in FM tracking for central lesions will also be reviewed. In conclusion, for PPLs, the endobronchial approach provides a low rate of pneumothorax, offers the possibility of concurrent diagnostic sampling for both the PPL and the lymph nodes, and, finally, reduces the intervention time compared to other techniques. In this context, coil-tailed and coil-spring FMs have shown the lowest migration rate with a consequently high tracking rate.

Real-time Markerless Tracking of Lung Tumors based on 2-D Fluoroscopy Imaging using Convolutional LSTM

Purpose

To investigate the feasibility of tracking targets in 2D fluor images using a novel deep learning network.

Methods

Our model design aims to capture the consistent motion of tumors in fluoroscopic images by neural network. Specifically, the model is trained by generative adversarial methods. The network is a coarse-to-fine architecture design. Convolutional LSTM (Long Short-term Memory) modules are introduced to account for the time correlation between different frames of the fluoroscopic images. The model was trained and tested on a digital X-CAT phantom in two studies. Series of coherent 2D fluoroscopic images representing the full respiration cycle were fed into the model to predict the localized tumor regions. In first study to test on massive scenarios, phantoms of different scales, tumor positions, sizes, and respiration amplitudes were generated to evaluate the accuracy of the model comprehensively. In second study to test on specific sample, phantoms were generated with fixed body and tumor sizes but different respiration amplitudes to investigate the effects of motion amplitude on the tracking accuracy. The tracking accuracy was quantitatively evaluated using intersection over union (IOU), tumor area difference, and centroid of mass difference (COMD).

Results

In the first comprehensive study, the mean IOU and dice coefficient achieved 0.93±0.04 and 0.96±0.02. The mean tumor area difference was 4.34%±4.04%. And the COMD was 0.16 cm and 0.07 cm on average in SI (superior-interior) and LR (left-right) directions, respectively. In the second amplitude study, the mean IOU and dice coefficient achieved 0.98 and 0.99. The mean tumor difference was 0.17%. And the COMD was 0.03cm and 0.01 cm on average in SI and LR directions, respectively. Results demonstrated the robustness of our model against breathing variations.

Conclusion

Our study showed the feasibility of using deep learning to track targets in x-ray fluoroscopic projection images without the aid of markers. The technique can be valuable for both pre- and during-treatment real-time target verification using fluoroscopic imaging in lung SBRT treatments.

Image-guided marking techniques in interventional radiology: A review of current evidence

Precise marking of lesions using image-guided techniques is essential, as imprecise targeting of a tumor can result in either insufficient excision/treatment with an increased risk of recurrence, or excessive removal of healthy tissue. Most frequent indications include localization of nonpalpable lesions before surgical resection (i.e., hook-wire localization of pulmonary nodules before video-assisted thoracoscopy) and definite marking of liver metastasis before neoadjuvant therapy. Other indications include marking of hepatocellular carcinomas that are not visible on ultrasound and unenhanced computed tomography before thermal ablation, of bone lesions before surgical excision, and of different visceral tumors before stereotactic radiotherapy. This review presents the different existing indications, assesses their usefulness, gives systematic details on the technique and lastly analyzes the current literature with emphasis on results and complications.

Comparison of technical success and safety of transbronchial versus percutaneous CT-guided fiducial placement for SBRT of lung tumors

OBJECTIVE

To evaluate the technical success and safety of transbronchial (bronchoscopic) fiducial placement compared to percutaneous CT-guided fiducial placement for stereotactic body radiotherapy (SBRT) of lung tumors.

MATERIALS AND METHODS

This IRB-approved, HIPAA-compliant retrospective study was performed at a single tertiary institution. Consecutive patients undergoing lung fiducial placement for purposes of guiding SBRT (CyberKnife®, Accuray, Inc.) between September 2005 to January 2013 were included in the study. Fiducial seeds were placed percutaneously with CT guidance or transbronchially with bronchoscopic guidance. We compared procedure-related complications (pneumothorax, chest tube placement), technical success (defined as implantation enabling adequate treatment planning with CT simulation) and migration rate. The need for repeat procedures and their mode was noted. Statistical analysis was performed using Fisher exact and Chi square probability tests.

RESULTS

Two hundred and forty-four patients with lung tumors and 272 fiducial seed placements were included in the study. Two hundred and twenty-one of the 272 (81.2%) fiducial markers were placed percutaneously and 51/272 (18.8%) were placed transbronchially. Pneumothorax was seen in 73/221 (33%) of percutaneously-placed fiducials and in 4/51 (7.8%) of transbronchial placements (p<0.001). No significant difference was seen in the rate of chest tube placement between the two groups: 20/221 (9%) of percutaneously placed fiducials and 2/51 (3.9%) of transbronchially placed fiducials (p=0.39). Fifteen of the 51 (29%) of fiducial placements with transbronchial approach were unsuccessful, as discovered at radiotherapy planning session, and required a repeat procedure. Nine of the 15 (60%) of repeat procedures were performed percutaneously, 5/15 (33%) were placed during repeat bronchoscopy, and 1/15 (7%) was placed at transesophageal endoscopic ultrasound. No repeat fiducial placements were required for patients who had the fiducials placed percutaneously (p<0.001), with a technical success rate of 100%.

CONCLUSION

Transbronchial fiducial marker placement has a significantly higher rate of failed seed placements requiring repeat procedures in comparison to percutaneous placement. Complication rate of pneumothorax requiring chest drain placement is similar between the two approaches.

Advanced Diagnostic and Therapeutic Bronchoscopy: Technology and Reimbursement

Advanced interventional pulmonary procedures of the airways, pleural space, and mediastinum continue to evolve and be refined. Health care, finance, and clinical professionals are challenged by both the indications and related coding complexities. As the scope of interventional pulmonary procedures expands with advanced technique and medical innovation, program planning and ongoing collaboration among clinicians, finance executives, and reimbursement experts are key elements for success. We describe advanced bronchoscopic procedures, appropriate Current Procedural Terminology coding, valuations, and necessary modifiers to fill the knowledge gap between basic and advanced procedural coding. Our approach is to balance the description of procedures with the associated coding in a way that is of use to the proceduralist, the coding specialist, and other nonclinical professionals.

Endobronchial coil spring fiducial markers for CyberKnife® stereotactic body radiation therapy

BACKGROUND AND OBJECTIVE

SBRT is an alternative treatment for early-stage inoperable lung cancer. Metallic FM allow to increase tumour tracking precision by CyberKnife®. Currently used techniques for FM placement have many limitations; transthoracic insertion has a high risk for pneumothorax, endovascular insertion requires expertise and dedicated angiography infrastructure and endobronchial linear-gold FM dislocate frequently. This is the first study to assess the safety and efficacy of cs-FM endobronchial insertion under fluoroscopy with or without R-EBUS assessment.

METHODS

We retrospectively evaluated all consecutive patients undergoing endobronchial cs-FM placement for at least one PPL <25 mm between 10.2015 and 12.2019. TBB of the PPL were performed in case of a typical R-EBUS signal. PPL tracking accuracy by CyberKnife, complications, cs-FM migration rate and procedure duration were analysed.

RESULTS

A total of 52 patients were treated during 55 procedures and 207 cs-FM were placed in 70 PPL. Tracking was successful for 65 of 70 (93%) PPL. R-EBUS was performed for 33 (47%) PPL and TBB for 9 (13%) PPL. Bronchospasm occurred once and any other complications were observed. Migration of cs-FM occurred in 16 of 207 (8%) cs-FM. Migration was more frequent when the target was in a previously irradiated area (P = 0.022). The median bronchoscopy duration was 31.5 min (n = 48 procedures).

CONCLUSION

Bronchoscopic cs-FM placement is a rapid and safe procedure. It is associated with a low migration rate and allows precise SBRT delivery. Previous irradiation of the PPL was associated with a higher migration rate.

Bronchoscopic treatments for early-stage peripheral lung cancer: Are we ready for prime time?

Lung cancer is the leading cause of cancer-related death worldwide and surgical lobectomy remains the preferred therapy for patients with early-stage NSCLC. Medical comorbidities and advanced age preclude resection in many patients and minimally invasive ablative therapies are needed for treatment. Stereotactic ablative radiation is established as an effective modality in this patient group, although may be contraindicated in some patients with prior radiation exposure, comorbidities or centrally positioned tumours. Percutaneous ablative methods are available, although are frequently associated with significant complications. Numerous endoscopic ablative techniques are under evaluation. With a more favourable safety profile and the ability to provide diagnosis and staging information potentially within a single procedure, there is a strong rationale for development of bronchoscopic ablative modalities. In the following article, the authors aim to explore the role bronchoscopic ablation may play in treatment of peripheral lung tumours, and to describe a pathway to establishing these modalities as part of routine care. The current status of several bronchoscopic ablative options is discussed in detail.

A simple endoscopic method with radial endobronchial ultrasonography for low-migration rate coil-tailed fiducial marker placement

Background

Fiducial markers (FMs) are useful for tracking small peripheral lung nodules (PLN) before stereotactic radiotherapy, but migration over the course of treatment may result in inaccurate dosing to the tumor. To minimize FM migration, coil-tailed FMs have been designed. Our objective was to assess both the feasibility of radial endobronchial ultrasonography (r-EBUS) placement and the migration rate of coil-tailed FMs.

Methods

In this retrospective study, we included patients who received r-EBUS guided placement of coil-tailed FMs for PLN <25 mm from June 2015 to May 2018. We introduced the FM into the nodule with the use of bronchial brush, without fluoroscopy.

Results

Thirty patients had r-EBUS guided placement of a coil-tailed FM before stereotactic radiation therapy. Nodule’s median long- and short-axis diameters were 15 mm (8–25 mm) and 8 mm (5–20 mm), respectively; short diameter of 27 nodules (90%) was less than 15 mm. All nodules were reached and visualized with r-EBUS, with an ultrasound (US) signal showing a centered or tangential probe in 26 and 4 cases, respectively. No immediate complication was reported. Twenty-three patients had stereotactic radiation therapy within a median time of 29 days (14–126 days). No FM migration occurred between r-EBUS placement and radiotherapy. Pre-treatment planning and 3-month follow-up CT scans showed that all FMs stayed in direct contact with the lesions.

Conclusions

r-EBUS is a safe procedure for the placement of nitinol coil FMs, which have a low migration rate.

Convex Probe EBUS-guided Fiducial Placement for Malignant Central Lung Lesions

BACKGROUND

Stereotactic body radiotherapy (SBRT) had become a therapeutic modality in patients with primary tumors, locally recurrent as well as oligometastasis involving the lung. Some modalities of SBRT require fiducial marker (FM) for dynamic tumor tracking. Previous studies have focused on evaluating bronchoscopic-guided FM placement for peripheral lung nodules. We describe the safety and feasibility of placing FM using real-time convex probe endobronchial ultrasound (CP-EBUS) for SBRT in patients with centrally located hilar/mediastinal masses or lymph nodes.

METHODS

This is a retrospective review of patients who were referred to Beth Israel Deaconess Medical Center's multidisciplinary thoracic oncology program for FM placement to pursue SBRT.

RESULTS

Thirty-seven patients who underwent real-time CP-EBUS were included. Patients had a median age of 71 years [interquartile range (IQR), 59.5 to 80.5]. The median size of the lesion was 2.2 cm (IQR, 1.4 to 3.3 cm). The median distance from the central airway was 2.4 cm (IQR, 0 to 3.4 cm). A total of 51 FMs (median of 1 per patient) were deployed in 37 patients. At the time of SBRT planning, 46 (90.2%) were confirmed radiologically in 32 patients. Patients with unsuccessful fiducial deployment (n=5) underwent a second procedure using the same technique. Of those, 3 patients had a successful fiducial placement via bronchoscopy, 1 patient required FM placement by percutaneous computed tomography-guided approach and 1 patient required FM placement through EUS by gastroenterology.

CONCLUSION

CP-EBUS-guided FM placement for patients with malignant lymph nodes and central parenchymal lung lesions appears to be safe and feasible.

Long term safety and visibility of a novel liquid fiducial marker for use in image guided radiotherapy of non-small cell lung cancer

Safety and clinical feasibility of injecting a novel liquid fiducial marker for use in image guided radiotherapy in 15 patients with non-small cell lung cancer are reported. No major safety or toxicity issues were encountered. Markers present at start of radiotherapy remained visible in cone beam computed tomography and fluoroscopy images throughout the treatment course and on computed tomography images during follow-up (0-38 months). Marker volume reduction was seen until 9 months after treatment, after which no further marker breakdown was found. No post-treatment migration or marker related complications were found.

Fiducial marker placement for stereotactic body radiation therapy via convex probe endobronchial ultrasound: a case series and review of literature

Convex probe endobronchial ultrasound (CP-EBUS) and stereotactic body radiotherapy (SBRT) are valuable tools in the diagnosis, staging, and treatment of thoracic malignancies. With widespread clinical adoption, novel uses of CP-EBUS beyond mediastinal diagnosis and staging continue to be discovered. SBRT is an attractive treatment strategy in early-stage lung cancer and oligo-metastatic disease of the chest when a surgical approach is either not feasible or desirable. Accurate application of SBRT is aided by the placement of radio-opaque fiducial markers (FM) to compensate for respiratory cycle movements. We describe eight patients with central thoracic lesions, either known or suspected to be malignant, who underwent EBUS bronchoscopy with lesion sampling and successful intralesional placement of modified FM via our technique, review the existing literature on this topic, and discuss the nuances of coding and billing aspects of FM placement.

Assessment of Per-Endoscopic Placement of Fiducial Gold Markers for Small Peripheral Lung Nodules < 20 mm Before Stereotactic Radiation Therapy

BACKGROUND

Stereotactic radiotherapy is used to treat peripheral lung cancer in inoperable patients. Placement of fiducial gold markers (FMs) is crucial for tracking small lesions that are not visible on chest radiographs. Our objective was to assess endoscopic FM placement in small peripheral lung nodules (PLNs) that are not trackable using automated tracking software.

METHODS

All patients benefiting from virtual bronchoscopy and radial endobronchial ultrasonography (R-EBUS)-guided placement of FMs for PLNs < 20 mm were included. After confirmation by biopsy sampling, a gold-seed FM was inserted into the nodule using a bronchial brush, without the use of fluoroscopy. The performance and complications of the procedure were recorded.

RESULTS

From May 2010 to June 2015, FMs were placed in the PLNs of 54 consecutive patients, 34 of whom presented with a nodule < 20 mm. Seventy-six percent of the procedures were performed using local anesthesia on an outpatient basis. The median long- and short-axis diameters of nodules were 15 mm (9-20 mm) and 11 mm (6-20 mm), respectively, with 31 of 34 nodules exhibiting a short axis of < 15 mm. In 23 cases (79%), histologic samples were obtained during the procedure that allowed FM placement. Migration occurred in six cases, including two in the hours following the procedure. FMs were in place and visible on CT imaging performed 3 months after radiation therapy in 80% of cases. No complications were reported.

CONCLUSIONS

Diagnosis of peripheral nodules < 20 mm and FM placement using R-EBUS are efficient and safe in a single procedure.

Magnitude, Impact, and Management of Respiration-induced Target Motion in Radiotherapy Treatment: A Comprehensive Review

Tumors in thoracic and upper abdomen regions such as lungs, liver, pancreas, esophagus, and breast move due to respiration. Respiration-induced motion introduces uncertainties in radiotherapy treatments of these sites and is regarded as a significant bottleneck in achieving highly conformal dose distributions. Recent developments in radiation therapy have resulted in (i) motion-encompassing, (ii) respiratory gating, and (iii) tracking methods for adapting the radiation beam aperture to account for the respiration-induced target motion. The purpose of this review is to discuss the magnitude, impact, and management of respiration-induced tumor motion.

Safety and feasibility of prolonged bronchoscopy involving diagnosis of lung cancer, systematic nodal staging, and fiducial marker placement in a high-risk population

BACKGROUND

Stereotactic body radiation therapy (SBRT) is considered the standard treatment for medically inoperable early stage lung cancer. Bronchoscopy has shown to be effective in obtaining diagnosis of peripheral lung tumors, staging the mediastinum (with endobronchial ultrasound- EBUS-), and placing fiducial markers (FMs). However, the combination of these 3 procedures in a single bronchoscopy has not been studied. The aim of this study is to describe safety and feasibility of performing diagnosis, systematic nodal staging, and placement of FMs in a single bronchoscopic procedure.

METHODS

Retrospective review of patients who underwent bronchoscopy with diagnosis of peripheral lung cancer, EBUS for nodal staging, and FM placement in a single procedure at Michael E. DeBakey VA Medical Center between January 2011 and July 2015.

RESULTS

Twenty-one patients met our criteria, one having 2 synchronous tumors. 95% of patients had an ASA score of at least 3. Twenty-two tumors were diagnosed with a size of 2.72±1.06 cm. Distance from pleura was 1.33±1.42 cm. Median duration of bronchoscopy was 96 minutes (range, 75 to 136 minutes). Guided-bronchoscopy provided diagnosis of lung cancer in all cases. Fluoroscopy and RP-EBUS were utilized in 21 patients, "hybrid" scope in 14, and electromagnetic navigational bronchoscopy in 3. A total of 100 lymph nodes (LN) were sampled with EBUS-TBNA, with 95% of the patients having at least 4 LN sampled. A total of 71 FM were placed for 22 tumors. All markers were retained and allowed for successful SBRT. There were no pneumothoraces and no major complications.

CONCLUSIONS

Although it results in lengthy procedures, a single bronchoscopy obtaining diagnosis of peripheral lung nodules, systematic nodal staging, and FM placement can be safely performed in high-risk patients. Our "all-in-one" strategy could potentially expedite treatment, decrease complications, and reduce costs. Further prospective studies are needed to corroborate our findings.

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.

Convex probe endobronchial ultrasound: applications beyond conventional indications

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is maturing and gaining acceptance by more and more clinicians for lymph node staging of lung cancer and diagnosis of mediastinal and hilar masses or lymph node enlargement by convex probe endobronchial ultrasound (CP-EBUS). The application of CP-EBUS, however, is not limited to conventional indications. Diagnostically, elastography is a new technology for the differentiation of benign and malignant lymph nodes before aspiration. CP-EBUS can also be used for pulmonary vascular diseases, such as pulmonary embolism (PE) and non-thrombotic endovascular lesions (NELs). Therapeutically, CP-EBUS can be used for cyst drainage and drug injections. CP-EBUS is not limited to observation and aspiration of mediastinal masses and lymph nodes, but is also suitable for exploration of other tissues external to the central airway, which necessitates unprecedented skills for the bronchoscopist.

Sequential multimodality bronchoscopic investigation of peripheral pulmonary lesions

Multiple guidance modalities may be combined during bronchoscopic investigation of peripheral pulmonary lesions (PPLs). The relative contribution of each modality to diagnostic performance remains uncertain.Endobronchial ultrasound (EBUS) with virtual bronchoscopy (VB) was routinely performed, with electromagnetic navigation (EMN) utilised only where EBUS was unable to locate PPLs or where the probe was adjacent to the lesion and on-site cytologic examination was nondiagnostic.236 consecutive patients with 245 PPLs had lesion size 22.8±12.4 mm (mean±sd). PPLs were localised using EBUS+VB alone in 188 (77%) and was diagnostic in 134 of these (71.3%). EBUS localisation was predicted by PPL size (23.7±10.5 versus 19.7±9.8 mm, p=0.003), but not by bronchus sign, PPL-hilum distance or PPL-pleura distance. EMN in 57 patients achieved EBUS localisation in a further 17 patients (30.9%), improving overall visualisation yield to 85%. Nine of these 57 procedures achieved a definitive diagnosis (16%), improving overall diagnostic yield to 58.4%. Probe position and lesion type influenced overall diagnostic yield. Sensitivity for diagnosis of lung cancer was 70% (131/188; 95% CI 63-76%).Localisation rate and diagnostic sensitivity of radial probe EBUS+VB alone for diagnosis of PPLs is high. EBUS localisation rates and procedural yield are improved only modestly (by 8% and 4%, respectively) with addition of EMN. Sampling following EMN should include all available methods to maximise diagnostic yield.