Virtual-assisted Lung Mapping Research Articles

Current trends in thoracic surgery.

ABSTRACTThoracic surgery has evolved drastically in recent years. Although thoracic surgeons mainly deal with tumorous lesion in the lungs, mediastinum, and pleura, they also perform lung transplantation surgery in patients with end-stage lung disease. Herein, we introduce various major current topics in thoracic surgery. Minimally invasive surgical procedures include robot-assisted thoracic surgery and uniportal video-assisted thoracic surgery. Novel techniques for sublobar resection include virtual-assisted lung mapping, image-guided video-assisted thoracic surgery, and segmentectomy using indocyanine green. Three-dimensional (3D) computed tomography (CT) simulation consists of surgeon-friendly 3D-CT image analysis systems and new-generation, dynamic 3D-CT imaging systems. Updates in cadaveric lung transplantation include use of marginal donors, including donation after circulatory death, and ex vivo lung perfusion for such donors. Topics in living donor lobar lung transplantation include size matching, donor issues, and new surgical techniques. During routine clinical practice, thoracic surgeons encounter various pivotal topics related to thoracic surgery, which are described in this report.

A meta-analysis of preoperative bronchoscopic marking for pulmonary nodules.

Recent studies have suggested the usefulness of preoperative bronchoscopic marking techniques for the localization of pulmonary nodules in thoracic surgery. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of preoperative bronchoscopic marking. The PubMed and Cochrane Library databases were searched for clinical studies evaluating preoperative bronchoscopic marking for pulmonary resection. Non-comparative and random effects model-based meta-analyses were conducted to calculate the pooled success and complication rates of bronchoscopic marking. Twenty-five eligible studies were included. Among these, 15 studies conducted dye marking under electromagnetic navigation bronchoscopy, 4 used virtual-assisted lung mapping and 7 used other marking methods. The overall pooled successful marking rate, successful resection rate and complete resection rate were 0.97 [95% confidence interval (CI) 0.95-0.99], 0.98 (95% CI 0.96-1.00) and 1.00 (95% CI 1.00-1.00), respectively. The overall pooled rates of pleural injury and pulmonary haemorrhage were 0.02 (95% CI 0.01-0.05) and 0.00 (95% CI 0.00-0.00), respectively. This meta-analysis demonstrated that bronchoscopic marking is very safe and effective. Bronchoscopic marking should be considered, especially if there are concerns about the safety of other localization methods.

Strategies to improve the accuracy of lung stapling in uniportal and multiportal thoracoscopic sublobar lung resections.

The challenges in video-assisted thoracic surgery for sublobar lung resection include difficulty in tumour localization by palpation and difficulty in determining appropriate resection lines. Virtual-assisted lung mapping (VAL-MAP), a bronchoscopic preoperative multispot lung dye-marking technique, allows for both tumour localization and determination of resection lines. To facilitate stapler-based resection, the AMAGAMI or 'incomplete grasping' stapler technique is useful to adjust the alignment of the stapler and resection lines. However, when the lung tissue to be stapled is thick, there is unavoidable uncertainty in the staple line inside the lung. We experimentally demonstrated that up to 1 cm of slippage of lung parenchyma occurs at stapling when the stapled lung tissue is >1 cm thick. VAL-MAP 2.0 is a new generation of VAL-MAP combining multispot dye markings with intrabronchial microcoil placement, allowing for 3-dimensional lung mapping and intraoperative navigation using fluoroscopy. The uncertainty of stapling in the lung parenchyma can be partly overcome by VAL-MAP 2.0.

Identification of the intersegmental plane during thoracoscopic segmentectomy: state of the art.

During thoracoscopic segmentectomy, where direct palpation of the tumour is not always possible, achieving adequate margins from the cancer is of crucial importance. It is thus mandatory to accurately identify the intersegmental plane (ISP). Indeed, inadequate determination and division of the ISP can lead to unsatisfactory oncological results. Our systematic review focused on the effectiveness of the different techniques for identifying the ISP, highlighting the fact that a 1-size-fits-all method is not feasible. Based on the published evidence, 6 main methods were reported, each with its pros and cons: inflation-deflation technique, selective resected segmental inflation, systemic injection of indocyanine green, injection of endobronchial dye, 3-dimensional simulation using multidetector computed tomography and virtual-assisted lung mapping. In conclusion, ISP demarcation is mandatory to achieve a high rate of success of thoracoscopic segmentectomy, and it is very helpful in surgical planning, especially when preoperative multidetector computed tomography and 3-dimensional reconstructions are routinely performed.

Precise sublobar lung resection for small pulmonary nodules: localization and beyond.

Early-stage primary lung cancer is increasingly detected by computed tomographic (CT) screening and the radicality of sublobar lung resection (wedge resection and segmentectomy) has been suggested. However, identification of a tumor intraoperatively becomes more difficult, the earlier a nodule is detected. A solution to this challenge is localization techniques. There are many techniques to localize small pulmonary nodules, including that replacing surgeon's tactile sensation, visualizing the tumor using ultrasound, and various types of lung markings that are placed percutaneously under CT guidance or bronchoscopically. The most commonly used technique is CT-guided placement of a hookwire, but there are concerns about potentially fatal air embolism. Bronchoscopic localization, especially using electromagnetic navigation bronchoscopy with or without intraoperative cone-beam CT imaging, has been increasingly reported. Beyond localization, the concept of lung "mapping" is emerging. In sublobar lung resection, in addition to localization of the targeted tumor, acquisition of sufficient resection margins is critical to prevent local recurrence. Virtual-assisted lung mapping (VAL-MAP) has evolved from bronchoscopic dye localization, but by placing multiple dye marks, it provides two-dimensional geometric information on the lung. Moreover, to ensure deep resection margins, the newly developed technique of VAL-MAP2.0 combining dye marks and intrabronchial placement of a microcoil enables three-dimensional lung mapping. This allows for intraoperative navigation of lung resection under a fluoroscope. Development of this field, such as using a new technology of augmented reality, will further enhance the accuracy and convenience of lung resection in the near future.

P2.17-26 Indocyanine Green Virtual Assisted Lung Mapping (ICG-VAL-MAP): Anyone Can Perform a Successful Preoperative Marking for a Small Lung Nodule

P2.17-26 Indocyanine Green Virtual Assisted Lung Mapping (ICG-VAL-MAP): Anyone Can Perform a Successful Preoperative Marking for a Small Lung Nodule

Protocol for the VAL-MAP 2.0 trial: a multicentre, single-arm, phase III trial to evaluate the effectiveness of virtual-assisted lung mapping by bronchoscopic dye injection and microcoil implementation in patients with small pulmonary nodules in Japan

IntroductionTumour localisation is important for successful resection of lung nodules with optimal resection margins in sublobar resection. Virtual-assisted bronchoscopic localisation technique combined with dye marking and microcoil placement (VAL-MAP 2.0)...

Virtual-Assisted Lung Mapping 2.0: Preoperative Bronchoscopic Three-Dimensional Lung Mapping

To better determine suitable resection lines for sublobar lung resection, especially to obtain sufficient resection depth, a novel technique of virtual-assisted lung mapping (VAL-MAP) 2.0 was developed by combining multispot dye marks (conventional VAL-MAP) and a deeply placed microcoil. With the patient under local anesthesia and sedation, multiple dye marks were bronchoscopically made on the lung surface. Microcoils were then bronchoscopically placed centrally to the tumor to indicate deep resection margins. Postmapping computed tomography confirmed the marking locations. Six patients underwent VAL-MAP 2.0: 5 for wedge resection and 1 for segmentectomy. The mean diameter and depth of the targeted lesions were 10.0 ± 4.1 and 12.6 ± 10.3 mm, respectively. In total, 18 dye marks and 9 microcoils were placed without major complications. The microcoils were successfully identified with intraoperative fluoroscopy, effectively assisting the surgeons' decision regarding the deep resection lines. This study confirmed the safety and feasibility of VAL-MAP 2.0. This technique effectively assisted surgeons to obtain sufficient resection margins in sublobar lung resection, even when removing deeply located lesions.

Concepts and techniques: how to determine and identify the appropriate target segment in anatomical pulmonary segmentectomy?

Anatomical segmentectomy is gathering increasing interest among thoracic surgeons because of increased detection of pulmonary nodules with ground-glass opacity (GGO) as well as an increase in the number of compromised patients. Accurate determination of intersegmental planes is a challenge in anatomical segmentectomy, and multiple methods have been proposed including developing inflation/deflation lines and injecting indocyanine green either intravenously or intrabronchially. Considering resection margins, adding a localization technique to conventional methods, or conducting virtual-assisted lung mapping (bronchoscopic multi-spot dye marking) may be an optional approach for optimal anatomical segmentectomy to identify intersegmental planes and obtain adequate resection margins. To determine optimal resection lines in anatomical segmentectomy, surgeons must also consider oncological validity such as venous and lymph drainage, resection margins, and lung anatomy to avoid complications such as venous congestion, infarction, and air leakage. Although anatomical segmentectomy is an attractive approach to resect small early-stage lung cancer and some metastatic lung tumors, caution is needed to optimally perform this technically demanding surgery.

Effect of patient position during virtual-assisted lung mapping.

Virtual-assisted lung mapping (VAL-MAP) is a preoperative multi-spot bronchoscopic dye-marking technique. Marking failure reportedly occurs in approximately 10% of marks. The aim of the present study was to investigate whether the patient position during dye injection in VAL-MAP affected the quality of markings. This study was a retrospective review of patients with barely palpable pulmonary nodules who underwent VAL-MAP at a single institution between December 2016 and September 2017. Easily visible markings without bulla formation were defined as "appropriate", while other markings were defined as "inappropriate". Patients were divided in accordance with the position during dye injection into the supine position group (n=6) and the lateral position group (n=8). The two groups were compared regarding the appropriate markings rate. The Fisher exact test and logistic regression model were used for statistical analyses. Fourteen patients with 17 nodules underwent VAL-MAP with a total of 48 markings (3.4±0.9 markings per patient). Of these, 21 markings were performed in supine position, whereas 27 were performed in lateral position. There were no significant differences between the two groups in lesion size, depth, and characteristics. Almost all of the performed procedures were thoracoscopic wedge resections (94%), while one procedure was thoracoscopic left upper division segmentectomy. The appropriate markings rate was significantly greater in the lateral position group than in the supine position group (88% vs. 57%, P=0.02). Among the markings located in dorsal and ventral lung segments, the appropriate markings rate in the lateral position group tended to be greater than that in the supine position group (89% vs. 59%, P=0.06). Multivariate logistic regression analysis revealed that the lateral position was independently associated with appropriate markings (P=0.014). The lateral position may enable the creation of better quality markings in VAL-MAP.

Latest update about virtual-assisted lung mapping in thoracic surgery.

Virtual-assisted lung mapping (VAL-MAP) is a preoperative bronchoscopic multi-spot dye-marking technique using virtual images developed to assist in navigational lung resection. The technique of VAL-MAP has been shown to be safe and effective surgical assistive tool for performing pulmonary sublobar resections. The technique is applicable for treating multiple small pulmonary lesions that are hardly palpable including ground glass nodules (GGNs). It also may help shorten surgical duration in wedge resection cases. Electromagnetic navigation bronchoscopy (ENB) may eliminate the need for post-mapping computed tomography (CT) scans in logistically challenged situations. In the most recent, multicenter prospective single-arm study, conventional VAL-MAP had reasonable efficacy for obtaining good surgical margin in pulmonary sublobar resections, although the successful resection rate did not reach the primary goal most significantly due to deep resection margins. The technique of VAL-MAP in combination with microcoil may be the next step to acquire better surgical margins.

The AMAGAMI technique: an easy technique to achieve precise stapling in thoracoscopic segmentectomy.

The "AMAGAMI" or "incomplete grasping" technique is used to adjust the location of the lung while gently grasping the lung tissue with a stapler. Thoracoscopic segmentectomy requires precise but complex stapling, while the surgical view and the number of available instruments are limited. In the AMAGAMI technique, instead of moving the stapler to the targeted position of the lung tissue, an unlocked stapler is used to hold the lung tissue at an easily accessible position, and the lung tissue can then be slid to the ideal resection line using forceps. To use the AMAGAMI technique effectively, "standing stitches" are very helpful in enabling visualization of the ideal resection lines. Standing stitches are placed along intersegmental lines that have been determined based on the information provided by virtual-assisted lung mapping (VAL-MAP) or other marking techniques; these stiches are usually placed at the corner of the targeted segment and in-between if necessary. Monofilament suture is used for standing stitches, and about 1 cm lengths are left to enable later visualization. As these stitches stick out of the lung surface even when viewed from a tangential angle, the direction of stapling is easily visualized in thoracoscopic surgery. These techniques are particularly useful in challenging segmentectomy requiring complex staple lines, such as S10 segmentectomy, and in surgery with limited instrumental access, such as uniportal thoracoscopic surgery.

Advances in techniques for identifying small pulmonary nodules.

Since the introduction of video-assisted thoracoscopic surgery, the demand for its use in resecting small pulmonary nodules has increased. In parallel, the development of high-resolution computed tomography has led to an increase in the detection of the early lung cancers appearing as nodules with ground-glass opacity. Several techniques to resect these small lesions have been devised, the most familiar of which is the use of a computed tomography-guided percutaneous hook wire. We recently developed virtual-assisted lung mapping to achieve safer and more reliable resection of these lesions. Virtual-assisted lung mapping is carried out using three-dimensional computed tomography, bronchoscopy, and fluoroscopically guided navigation to mark the lung surface with dye. A prospective study showed that this technique was safe and had a high success rate. Multiple marking around the targeted lesion allows for a sufficient surgical margin at resection. We recently introduced an electromagnetic navigation bronchoscopy system to confirm the sites to be marked by virtual-assisted lung mapping in the operating room prior to video-assisted thoracoscopic surgery. We are now studying a method to enable minimally invasive, safe, and reliable resection of lesions located deep in the lung parenchyma.

P1.16-45 Thoracoscopic Stapler-Based Complex Segmentectomy Assisted by Virtual Assisted Lung Mapping

P1.16-45 Thoracoscopic Stapler-Based Complex Segmentectomy Assisted by Virtual Assisted Lung Mapping

P2.16-27 Indocyanine Green Virtual Assisted Lung Mapping (ICG-VAL-MAP): Anyone Can Perform a Visible Preoperative Marking Successfully

P2.16-27 Indocyanine Green Virtual Assisted Lung Mapping (ICG-VAL-MAP): Anyone Can Perform a Visible Preoperative Marking Successfully

Combined virtual-assisted lung mapping (VAL-MAP) with CT-guided localization in thoracoscopic pulmonary segmentectomy

Virtual assisted lung mapping (VAL-MAP) is a bronchoscopic lung marking technique developed to assist in navigational lung resection. It can be used for nodule localization and segmental identification. This article presents our initial experience of thoracoscopic pulmonary segmentectomy using combined VAL-MAP and computed tomography (CT)-guided localization. Markings with India Ink were made bronchoscopically, before surgery, using a virtual bronchoscopy system (LungPoint® Planner) without fluoroscopy guidance. Post VAL-MAP CT scans localized the actual markings. All data on patients, markings, and outcomes were retrospectively collected, and the contribution of VAL-MAP to the operation was graded by the surgeon. From March 2017 to September 2017, 24 consecutive patients received the VAL-MAP marking procedure before thoracoscopic segmentectomy. Nineteen patients also received pre-operative CT-guided percutaneous localization after VAL-MAP; fifteen patients received CT-guided localization with dye (patent blue V) and microcoil, and four patients received with dye only. Of the 101 marking attempts made in all the patients, 71 (70.3%) were identified as contributing to the surgery. No clinically evident complications were associated with the procedure. A total of 24 segmentectomies were thoracoscopically conducted for 18 cases of lung cancer and six cases of benign diseases. The combination of VAL-MAP and CT-guided percutaneous localization contribute to precise thoracoscopic pulmonary segmentectomy.

Effect of virtual-assisted lung mapping in acquisition of surgical margins in sublobar lung resection

ObjectiveVirtual-assisted lung mapping is a preoperative bronchoscopic multi-spot dye-marking technique. This study aimed to examine the efficacy of virtual-assisted lung mapping for obtaining sufficient surgical margins in sublobar lung resection. MethodsThe multicenter, prospective, single-arm study was conducted from September 2016 to July 2017 in 19 registered centers. Patients who required sublobar lung resection and careful determination of resection margins underwent virtual-assisted lung mapping followed by thoracoscopic surgery. Successful resection was defined as resection of the lesion with margins greater than the lesion diameter or 2 cm using the preoperatively planned resection without additional resection. We defined the primary goal of the study as achieving successful resection in 95% of lesions. ResultsThe resection of 203 lesions (average diameter, 9.6 ± 5.3 mm) was intended in 153 patients. The lesions included pure and mixed ground-glass nodules (75 [35.9%] and 36 [17.2%], respectively), solid nodules (91 [43.5%]), and others (7 [3.3%]). Surgical procedures included wedge resection (131, 71.2%), segmentectomy (51, 27.7%), and others (2, 1.1%). Successful resection was achieved in 178 lesions (87.8% [95% confidence interval, 82.4-91.9%]), and virtual-assisted lung mapping markings successfully aided in the identification of 190 lesions (93.6% [95% confidence interval, 89.3-96.5%]). Multivariable analysis showed that the most significant factor affecting resection success was the depth of the necessary resection margin (P = .0072). ConclusionsThis study showed that virtual-assisted lung mapping has reasonable efficacy, although the successful resection rate did not reach the primary goal. The depth of the required margin was the most significant factor leading to resection failure.

The role of virtual-assisted lung mapping in the resection of ground glass nodules.

Virtual-assisted lung mapping (VAL-MAP), a bronchoscopic multi-spot dye-marking technique, was tested for its ability to resect ground glass nodules (GGNs) in sublobar lung resections. All patients were prospectively registered in the multi-institutional lung mapping (MIL-MAP) study using VAL-MAP. The data were retrospectively analyzed, focusing on GGNs. GGN characteristics, pathological findings, operation type, and the surgical contribution of VAL-MAP were evaluated. The 370 GGNs in 299 patients included 257 pure and 113 mixed GGNs. There were 146 wedge resections (43.6%), 99 simple segmentectomies (29.6%), and 60 complex segmentectomies (18.0%). The largest number of marks were used in complex segmentectomy (4.05±0.74), followed by simple segmentectomy (3.35±0.97) and wedge resection (2.96±0.80). The overall successful resection rate was 98.6%. Multiple [2-5] GGNs were concurrently targeted by VAL-MAP in 53 patients (17.7%) with 123 GGNs. Two concurrent resections were conducted in 36 patients (12.1%), most commonly wedge resection and segmentectomies (21 patients). Among 190 sub-centimeter GGNs, 24 out of 51 GGNs ≤5 mm in diameter (47.1%) and 113 of 139 GGNs >5 mm in diameter (81.3%) were primary lung cancer (P<0.0001). Regarding the contribution of VAL-MAP to successful resection, wedge resection and pure GGNs were graded higher than both other resection types and mixed GGNs. VAL-MAP enabled thoracoscopic limited resection of GGNs. Its multiple marks facilitated resections of multi-centric GGNs. Resected suspicious GGNs >5 mm in diameter are likely to be lung cancer. VAL-MAP may impact decision-making regarding the indications and type of surgery for suspicious small GGNs.

Thoracoscopic stapler-based "bidirectional" segmentectomy for posterior basal segment (S10) and its variants.

Thoracoscopic segmentectomy for the posterior basal segment (S10) and its variant (e.g., S9+10 and S10b+c combined subsegmentectomy) is one of the most challenging anatomical segmentectomies. Stapler-based segmentectomy is attractive to simplify the operation and to prevent post-operative air leakage. However, this approach makes thoracoscopic S10 segmentectomy even more tricky. The challenges are caused mostly from the following three reasons: first, similar to other basal segments, "three-dimensional" stapling is needed to fold a cuboidal segment; second, the belonging pulmonary artery is not directly facing the interlobar fissure or the hilum, making identification of target artery difficult; third, the anatomy of S10 and adjacent segments such as superior (S6) and medial basal (S7) is variable. To overcome these challenges, this article summarizes the "bidirectional approach" that allows for solid confirmation of anatomy while avoiding separation of S6 and the basal segment. To assist this approach under limited thoracoscopic view, we also show stapling techniques to fold the cuboidal segment with the aid of "standing stiches". Attention should also be paid to the anatomy of adjacent segments particularly that of S7, which tends to be congested after stapling. The use of virtual-assisted lung mapping (VAL-MAP) is also recommended to demark resection lines because it flexibly allows for complex procedures such as combined subsegmentectomy such as S10b+c, extended segmentectomy such as S10+S9b, and non-anatomically extended segmentectomy.

Virtual-assisted lung mapping (VAL-MAP) shortened surgical time of wedge resection.

The detection of extremely small lung tumors has increased with the development of computed tomography. Resection of such tumors by thoracoscopy is often hindered due to the unclear location of the tumor. Various methods of preoperative determination of such lesions have been attempted, but without marked success. Here we used virtual-assisted lung mapping (VAL-MAP) to perform surgical resection of small lung lesions. We selected patients with pulmonary tumors that we anticipated to be difficult to identify during thoracoscopy and/or decide the resection line for sub-lobar lung resection. The wedge resections in the VAL-MAP group were compared to a group of patients who underwent wedge resection without VAL-MAP in 2013. Surgery duration was significantly shorter in the VAL-MAP group (average: 76.4 min) than in the 2013 group (average: 108.6 min; P=0.000451), although the VAL-MAP group (average major axis: 9.6 mm) had smaller tumors (P=0.000032) and more pure ground-glass opacities (GGOs) (P=0.0000919) than the 2013 group (average major axis: 16.6 mm). The findings of this study indicate that VAL-MAP is efficacious. In particular, VAL-MAP resulted in a shorter surgery duration and has expanded the indications of resectable lesions.