Virtual-assisted Lung Mapping Research Articles

Current Status and Future Perspectives of Preoperative and Intraoperative Marking in Thoracic Surgery.

The widespread implementation of lung cancer screening and thin-slice computed tomography (CT) has led to the more frequent detection of small nodules, which are commonly referred to thoracic surgeons. Surgical resection is the final diagnostic and treatment option for such nodules; however, surgeons must perform preoperative or intraoperative markings for the identification of such nodules and their precise resection. Historically, hook-wire marking has been performed more frequently worldwide; however, lethal complications, such as air embolism, have been reported. Therefore, several surgeons have recently attempted to develop novel preoperative and intraoperative markers. For example, transbronchial markings, such as virtual-assisted lung mapping and intraoperative markings using cone-beam computed tomography, have been developed. This review explores various marking methods that have been practically applied for a better understanding of preoperative and intraoperative markings in thoracic surgery. Recently, several attempts have been made to perform intraoperative molecular imaging and dynamic virtual three-dimensional computed tomography for the localization, diagnosis, and margin assessment of small nodules. In this narrative review, the current status and future perspectives of preoperative and intraoperative markings in thoracic surgery are examined for a better understanding of these techniques.

Uniportal thoracoscopic extended right apical segmentectomy with virtual-assisted lung mapping: a case report

BackgroundPulmonary extended segmentectomy is an optional surgical treatment for early-stage non-small cell lung cancer that helps to achieve optimal surgical margins. Here, we describe a challenging instance of extended segmentectomy via uniportal video-assisted thoracic surgery with virtual-assisted lung mapping, a preoperative bronchoscopic dye marking procedure.Case presentationA 72-year-old woman presented with two tumors that were clinically diagnosed as early-stage lung cancer; extended right apical segmentectomy was indicated. Because the tumors had appeared unidentifiable intraoperatively, we performed virtual-assisted lung mapping for tumor localization and delineation of the optimal resection area. Surgery was conducted through a single port. All virtual-assisted lung mapping markings were visible. After dissection of the apical vessels and bronchi, a putative intersegmental line was determined using collateral ventilation. Based on the putative intersegmental plane identified by collateral ventilation and the virtual-assisted lung mapping markings, the resection line was delineated. Extended apical segmentectomy along the resection line was successfully performed via uniportal video-assisted thoracic surgery. The postoperative course was uneventful. The pathological diagnosis was minimally invasive adenocarcinoma and adenocarcinoma in situ.ConclusionsVirtual-assisted lung mapping can help to achieve optimal extended segmentectomy via uniportal video-assisted thoracic surgery.

Ten-Year Outcome and Development of Virtual-Assisted Lung Mapping in Thoracic Surgery

Virtual-assisted lung mapping (VAL-MAP) is a preoperative bronchoscopic multispot dye-marking technique used in sublobar lung resection of barely palpable lung nodules. This review summarizes the history and outcomes of the VAL-MAP procedure. VAL-MAP was developed in 2012, and long-term outcomes of lung resection using VAL-MAP have recently been verified. Problems associated with conventional VAL-MAP include a prerequisite of post-mapping computed tomography (CT), occasional inability to see dye marks during surgery, and infrequent resection failure due to deep resection margins; various techniques have been developed to address these issues. VAL-MAP using electromagnetic navigation bronchoscopy with on-site adjustment can omit post-mapping CT. The use of indocyanine green in VAL-MAP has increased the success rate of marking detection during surgery without causing additional complications. VAL-MAP 2.0-a three-dimensional mapping technique that involves the intrabronchial placement of a microcoil-has increased the accuracy of sublobar resection, particularly for deeply located tumors. Although these promising new techniques have some limitations, they are beneficial for sublobar lung resection.

Number of dye marks required in virtual-assisted lung mapping.

Virtual-assisted lung mapping is a preoperative bronchoscopic multi-spot dye-marking technique used in sublobar lung resection for hardly palpable lung nodules. However, the number of marks required per nodule remains unknown. Therefore, we examined the correlation between the number of intraoperative visible marks and the successful resection rate. We retrospectively examined 210 consecutive patients with 256 lesions who underwent virtual-assisted lung mapping during January 2014-December 2020 at our hospital. When a nodule was not resected at the initial attempt, or when a nodule was very close to the cut margin in the resected specimen and required additional resection, we categorized it as unsuccessful resection. We divided 256 lesions into successful and unsuccessful groups and compared the numbers of intraoperative visible marks between the two groups. Of 797 attempted marks, 738 (92.4%) were visible during the surgery. Fourteen (5.4%) of 256 lesions were determined to be unsuccessful according to the study criteria. There was a remarkable difference in the average numbers of intraoperative visible marks between both groups (3 [interquartile range: 2-4] vs. 2 [interquartile range: 1-2.8]; p < 0.01). Multivariable logistic analysis revealed a significant difference in the number of intraoperative visible marks (odds ratio: 0.28, 95% confidence interval: 0.14-0.57; p < 0.001) between both groups. Successful sublobar lung resection requires three or more intraoperative visible marks established using virtual-assisted lung mapping per lung nodule.

Availability of virtual-assisted lung mapping affects procedure selection for early-stage lung cancer: a web-based cross-sectional study

The availability of new techniques may affect surgeons' procedure selection and thereby affect clinical outcomes. This study aimed to evaluate the effect of the availability of virtual-assisted lung mapping (VAL-MAP) on the selection of lung resection methods. Members of the Japanese Association for Chest Surgeons were invited to participate in a web-based survey. Participants were divided into those who had never used VAL-MAP (group 0), those who had used only VAL-MAP 1.0 (multiple dye marks on the pleural surface; group 1) and those who had used VAL-MAP 2.0 (multiple dye marks and intrabronchial microcoils for three-dimensional mapping; group 2). Participants were shown chest computed tomography images of 6 ground-glass opacity nodules and asked to choose surgical procedures to resect the nodules with sufficient resection margins greater than the lesion diameter or 2 cm. There were 197 surgeons in group 0, 49 in group 1 and 26 in group 2. All groups showed a similar trend of avoiding wedge resection for deeply located nodules. However, group 1 showed a trend of disagreeing with the selection of wedge resection compared with group 0 as measured by a Likert scale (1-5) by -0.21 points (95% confidence interval, -0.41 to -0.008 points, P = 0.042). This tendency disappeared in group 2. The availability of VAL-MAP 1.0 led to the selection of segmentectomy, while the availability of VAL-MAP 2.0 led to aggressive deep wedge resection.

Comparison of various lung intersegmental plane identification methods.

Keeping a sufficient surgical margin free of tumor is important to prevent local recurrence in lung segmentectomy. Accurate identification of the intersegmental plane is essential to achieve adequate surgical margins. Traditionally, the inflation-deflation method was used to identify the intersegmental plane. However, in recent years, various intersegmental plane identification methods, including systemic indocyanine green injection, have been reported and shown to be useful. The purpose of this review was to evaluate the identification rates, advantages, and disadvantages of various intersegmental identification methods in lung segmentectomy. There are primarily six methods: inflation-deflation method, selective segmental inflation, endobronchial dye injection, virtual-assisted lung mapping, systemic indocyanine green injection, and pure oxygen method. These are broadly classified into those that use bronchi and pulmonary arteries anatomically and those that use air and dye technically. In this review, all methods showed relatively high identification rates. Moreover, high identification rates were expected, especially with systemic indocyanine green injection and the pure oxygen method. Each method has its advantages and disadvantages as varying situations entail different methods. It is necessary to select and apply them effectively; therefore, further improvement for each method will be required in the future.

The role of virtual-assisted lung mapping 2.0 combining microcoils and dye marks in deep lung resection.

Virtual-assisted lung mapping 2.0 is a novel preoperative bronchoscopic lung mapping technique combining the multiple dye marks of conventional virtual-assisted lung mapping with intrabronchial microcoils to navigate thoracoscopic deep lung resection. This study's purpose was to evaluate the feasibility of virtual-assisted lung mapping 2.0 in resecting deeply located pulmonary nodules with adequate margins. A multicenter, prospective single-arm study was performed from 2019 to 2020 in 8 institutions. The selection criteria were barely identifiable nodules requiring sublobar lung resections, nodules requiring resection lines reaching the inner 2/3 of the pulmonary lobe on computed tomography images in wedge resection, or the nodule center located in the inner 2/3 of the pulmonary lobe in wedge resection or segmentectomy. Resection margins larger than 2cm or the nodule diameter were considered successful resection. Bronchoscopic placement of multiple dye marks and microcoil(s) was conducted 0 to 2days before surgery. We analyzed 65 lesions in 64 patients. The diameter and depth of the targeted nodules and the minimum required resection depth reported as median (interquartile range) were 9 (7-13) mm, 11 (5-15) mm, and 30 (25-35) mm, respectively. Among 60 wedge resections and 5 segmentectomies, successful resection was achieved in 64 of 65 resections (98.5%; 95% confidence interval, 91.7-100). Among 75 microcoils placed, 3 showed major displacement after bronchoscopic placement. There were no severe adverse events associated with the virtual-assisted lung mapping procedure. This study demonstrated that virtual-assisted lung mapping 2.0 can facilitate successful resections for deep pulmonary nodules, overcoming the limitations of conventional virtual-assisted lung mapping.

Commentary: Practicing the philosophy of continuous improvement with virtual-assisted lung mapping 2.0

Lung cancer screening programs have led to an increase in detection of small, semisolid or ground glass nodules concerning for malignancy.1,2 Without the ability to palpate these nodules, thoracic surgeons require precise intraoperative localization methods to perform sublobar resections with clear oncologic margins. One such method is virtual-assisted lung mapping (VAL-MAP). Now routine in Japan, VAL-MAP uses preoperative bronchoscopic placement of multiple dye marks on the lung surface to localize the nodule and guide the direction of the staple line to obtain adequate margins.

Virtual-assisted lung mapping using dual staining with indocyanine green and indigo carmine enhanced marking detectability.

BackgroundVirtual-assisted lung mapping (VAL-MAP) is a preoperative bronchoscopic multispot dye-marking procedure to facilitate sublobar lung resection for unidentifiable lung nodules. To increase detectable markings, we performed VAL-MAP using dual staining (VAL-MAP DS) with indocyanine green (ICG) and indigo carmine. This study was designed to evaluate the efficacy and safety of the modified technique.MethodsWe retrospectively reviewed the records of patients who underwent VAL-MAP DS. Twenty patients with 27 lesions underwent 72 VAL-MAP DS markings. We investigated the overall detectable marking rate, visible marking rate, successful resection rate, and complications.ResultsThe overall detectable marking rate, thanks to both ICG and indigo carmine, tended to be higher than the indigo carmine visible marking rate (95.7% vs. 85.5%, P=0.08). The successful resection rate with sufficient margins was 92.0%. There were no adverse events related to the use of ICG. ICG markings of the lungs of patients with a history of smoking more than 50 pack-years tended to be visible, but the staining was too extensive compared with the staining in patients who smoked less or not at all (58.8% vs. 0.0%, P<0.001).ConclusionsVAL-MAP DS is likely be efficacious and safe in enhancing the detectability of markings. This bronchoscopic technique should be considered as one of the optimal preoperative marking methods in thoracic surgery.

Virtual-assisted lung mapping in sublobar resection of small pulmonary nodules, long-term results.

The short-term efficacy of virtual-assisted lung mapping (VAL-MAP), a preoperative bronchoscopic multi-spot lung-marking technique, has been confirmed in 2 prospective multicentre studies. The objectives of this study were to analyse the local recurrence and survival of patients enrolled in these studies, long-term. Of the 663 patients enrolled in the 2 studies, 559 patients' follow-up data were collected. After excluding those who did not undergo VAL-MAP, whose resection was not for curative intent, who underwent concurrent resection without VAL-MAP, or who eventually underwent lobectomy instead of sublobar resection (i.e. wedge resection or segmentectomy), 422 patients were further analysed. Among 264 patients with primary lung cancer, the 5-year local recurrence-free rate was 98.4%, and the 5-year overall survival (OS) rate was 94.5%. Limited to stage IA2 or less (≤2 cm in diameter; n = 238, 90.1%), the 5-year local recurrence-free and OS rates were 98.7% and 94.8%, respectively. Among 102 patients with metastatic lung tumours, the 5-year local recurrence-free rate was 93.8% and the 5-year OS rate was 81.8%. Limited to the most common (colorectal) cancer (n = 53), the 5-year local recurrence-free and OS rates were 94.9% and 82.3%, respectively. VAL-MAP, which is beneficial in localizing small barely palpable pulmonary lesions and determining the appropriate resection lines, was associated with reasonable long-term outcomes. 152, 1542.

Risk Factors for Invisible Intraoperative Markings After Virtual-Assisted Lung Mapping

BackgroundVirtual-assisted lung mapping (VAL-MAP) is a preoperative bronchoscopic multispot dye-marking technique that can be combined with bronchoscopic placement of a microcoil (VAL-MAP 2.0). VAL-MAP can identify unpalpable pulmonary lesions; however, the markings are occasionally deemed invisible intraoperatively. We investigated preoperative risk factors for invisible markings after VAL-MAP. MethodsWe prospectively performed preoperative VAL-MAP in patients at the University of Tokyo between January 2014 and June 2020. Data of 219 patients (257 lesions) and 857 markings were retrospectively reviewed. Dye markings were categorized as grade 0 (invisible) or 1-5 (visible). The risk factors for grade 0 markings were assessed using multiple logistic regression analysis. Subsegments of the bronchus showing grade 0 markings were also evaluated for 133 lesions and 504 markings without missing data for the target segment. ResultsSixty-one of the 257 lesions (24%) displayed ≥1 grade 0 markings. Seventy-six (8.9%) of the 857 markings were grade 0 intraoperatively. VAL-MAP 1.0 was performed for 202 (79%) and 25 lesions (10%) without and with electromagnetic navigation bronchoscopy, and VAL-MAP 2.0 with a microcoil was performed for 30 lesions (11%). Upper lobe markings were associated with a significantly increased risk of invisible markings. There was no significant difference in the frequency of grade 0 markings among the VAL-MAP methods. Among all bronchi subsegments, left B1+2c exhibited the highest rate of grade 0 markings. ConclusionsMarkings placed using VAL-MAP are more likely to be invisible for upper lobe pulmonary lesions. Injecting markings for lesions in the left S1+2c thus require caution.

P02.01 CT Integrated Bronchoscopy Manual Spraying Pigment Labeling to Localize of Small Pulmonary Nodules

Popularization of High Resolution Computed Tomography (HRCT) has greatly improved the detection rate of pulmonary nodules. Video Assistant Thoracic Surgery (VATS) lobectomy (sublobar lung resection in selected patients) has been the standard surgical treatment for these early stage non-small cell lung cancer. Uniportal VATS, a widely used innovative technique in minimally invasive thoracic surgery, makes less incision and also demands more precise intraoperative palpation/localization which is often challenging for small nodules. Various strategies such as the hookwire method, CT fluoroscopy-guided bronchoscopic dye marking, contrast median injection, radiotracer localization and a virtual assisted lung mapping technology (VAL-MAP). While they provide new options of nodule location for thoracic surgeons, all of these strategies require expensive hardware or software and additional two or three more doctors which are often not affordable for centers with limited resources. The purpose of this study is to develop a practically cheap method of pigment labeling for bronchoscope with no additional need of medical equipment and medical human resources. This is an ethic committee approved clinical trial. Medically operable patients with the HRCT detected small nodules were eligible. This nodule localization method involved a manual drawing the route by the surgeon/bronchoscopist, through a series of bronchial opening sketches and marking the leading bronchus at every bifurcation point based on the HRCT. Two to four appropriate bronchial pathways were selected for each lesion. A metal-tip catheter was inserted into a selected bronchus and advanced to the pleura. The location of the catheter tip was fluoroscopically confirmed, and 1 mL of diluted methylene blue was injected for each marking. All these procedures were completed by one doctor and one nurse. Then low dose CT scan was used to visualize the localization of the multiple markings, which were used as references in the subsequent operation. Success rate and procedure related complication are reported. From April 2019 to July 2020, 18 lesions in 17 patients were enrolled. All surgical procedures were performed using uniportal VATS. The lesions ranged in size from 3 to 23mm, 15 (83%) were nodules of Ground Glass Opacity (GGO). The depth ranged from 0 to 19 mm. A total of 57 lung markings were planned. 54 of them (95%) were completed. Of the 3 failed markings, the target bronchus could not be accessed under the bronchoscopy because of improper angle. Fifty-two (91%) were visible during the operations. The 3 unidentified markings were in the same patient, who had been a coal miner and had a severe carbon deposition on his lung and pleura. There was no adverse event associated with this manual marking procedures. All lesions were successfully resected. In 3 patients failed multiple markings, alternative localization was used successfully. This HRCT guided manual drawing method of lesion localization is safe and effective for small nodule localization for lung cancer surgery. Results of this study appears to be better than conventional percutaneous techniques in clinically evident complications. Because it does not need special equipment, it is more suitable for developing countries with limited equipment and human resources.

Improved visualization of virtual-assisted lung mapping by indocyanine green.

ObjectivesVirtual-assisted lung mapping (VAL-MAP) is a bronchoscopic marking method of dye application on the surface of the lungs before resecting nonpalpable nodules. However, in some cases, it can be difficult to identify the markings of VAL-MAP on computed tomography and intraoperative thoracoscopy. We developed and assessed the feasibility of indocyanine green VAL-MAP (ICG-VAL-MAP).MethodsA historical control trial was conducted to investigate the effectiveness of ICG-VAL-MAP for marking visualization compared with that of VAL-MAP. In ICG-VAL-MAP, instead of indigo carmine, ICG and computed tomography contrast agents were used for dye marking, and near-infrared fluorescence endoscopy was employed to visualize the ICG markings. The other processes in VAL-MAP were carried out. The marking visibility was assessed in 3 grades of easy, faint, or not identifiable. We compared the visibility of the markings on computed tomography images and during thoracoscopic operations between VAL-MAP (567 markings in 147 cases) and ICG-VAL-MAP (142 markings in 63 cases).ResultsOn the preoperative computed tomography images, ICG-VAL-MAP provided significantly better marking visualization than VAL-MAP (easy/faint/not identifiable = 142/0/0 vs 427/100/30; P < .0001). ICG-VAL-MAP provided significantly better intraoperative markings than VAL-MAP (easy/faint/not identifiable = 141/0/1, respectively, vs 475/50/42, respectively; P < .0001). Regarding complications, pneumothorax occurred in 8 (5.4%) cases of VAL-MAP and zero cases (0%) of ICG-VAL-MAP (P = .12); fever was observed in 7 (5.0%) cases of VAL-MAP and 2 (3.2%) cases of ICG-VAL-MAP (P = .72).ConclusionsICG-VAL-MAP provided significantly better visibility of markings than VAL-MAP. It might be useful in the resection of nonpalpable small lung lesions.

切除支援気管支鏡下肺マッピング（VALMAP）を用いて肺部分切除術を行った肺原発髄膜腫の1症例

切除支援気管支鏡下肺マッピング（VALMAP）を用いて肺部分切除術を行った肺原発髄膜腫の1症例

Palpitation and virtual-assisted lung mapping: not mutually exclusive but complementary to facilitate sublobar lung resection.

Palpitation and virtual-assisted lung mapping: not mutually exclusive but complementary to facilitate sublobar lung resection.

Fluorescence-guided thoracic surgery

: Recently, the use of sublobar resection has become increasingly common for patients that were previously planned to undergo lobectomy. We encountered two challenges when performing sublobar resections for patients with small pulmonary nodules; one challenge was obtaining a sufficient surgical margin and the other was identifying the location of the nodules, especially in minimally invasive surgery. In recent years, indocyanine green (ICG) fluorescence has been used to solve these two problems in thoracic surgery: first, identifying the accurate intersegmental plane in anatomical lung segmentectomy for detecting the regions of residual pulmonary blood flow, and second, displaying the tumor location or optimal resection line intraoperatively as ICG virtual-assisted lung mapping (ICG-VAL-MAP). The purpose of this article is to present a review of the outcomes of fluorescence-guided thoracic surgery, and also our techniques in minimally invasive surgery using ICG fluorescence. We showed that patients received anatomical pulmonary resection that identified the intersegmental or interlobar plane using ICG guidance in video-assisted thoracic surgery (VATS) or in robot-assisted segmentectomy. We also showed that patients received pulmonary wedge resection, displaying the tumor location intraoperatively using ICG. Furthermore, we introduced a technique of preoperative transbronchial lung marking for small lung nodules called ICG-VAL-MAP. Fluorescence guidance in minimally invasive thoracic surgery makes it possible to ensure a safe surgical margin and identify the intersegmental line and location of the nodules accurately.

Initial experience of virtual-assisted lung mapping utilizing both indocyanine green and indigo carmine

Virtual-assisted lung mapping is a bronchoscopic multiple dye marking technique that facilitates sublobar lung resections for unidentifiable pulmonary tumors. Marking failure reportedly occurs in 10% of cases. To overcome this limitation, we developed indocyanine green virtual-assisted lung mapping that uses indocyanine green in addition to indigo carmine. Here, we report our initial experience of indocyanine green virtual-assisted lung mapping.

Virtual-assisted lung mapping: is it actually better than finger palpation?

Virtual-assisted lung mapping: is it actually better than finger palpation?

Hybrid technique of virtual-assisted lung mapping and systemic indocyanine green injection for extended segmentectomy

BackgroundVarious approaches have been used to assist and facilitate segmentectomy with favorable oncological outcomes. We describe a hybrid approach comprising virtual-assisted lung mapping (VAL-MAP), which is a preoperative bronchoscopic dye-marking technique, combined with systemic indocyanine green (ICG) injection.Clinical presentationAn asymptomatic 64-year-old man was referred to our department because of a lung nodule detected during his annual medical checkup. The chest computed-tomography image revealed a 16-mm, partly solid, ground-glass nodule in the left segment 4. Because the nodule was hardly palpable and deeply located between the left upper division segment and the left lingular segment, we performed VAL-MAP to facilitate extended left lingulectomy. Five dye markings were undertaken preoperatively. Surgery to remove the nodule was then conducted via complete three-port video-assisted thoracic surgery. The VAL-MAP markings were easily identified intraoperatively and helped locate the nodule. The intersegmental plane was identified by the ICG injection. The resection line was determined based on the intersegmental plane identified by the ICG injection and the site of the nodule suggested by the VAL-MAP markings. Following the resection line, we thoracoscopically achieved extended lingulectomy with sufficient surgical margins. The patient was discharged with no complications. The pathological diagnosis was adenocarcinoma in situ.ConclusionThe hybrid technique of VAL-MAP and systemic ICG injection can be useful for accomplishing successful extended segmentectomy.

Preoperative lung surface localization for pulmonary wedge resection: a single-center experience.

BackgroundPreoperative lung surface localization is effective in sublobar resection for small lung nodules. However, the efficacy may vary depending on the underlying conditions of the lung and tumor, as well as the technique. This study aimed to evaluate the efficacy and limitations of preoperative lung surface localization for wedge resection by analyzing the outcomes of computed tomography (CT)-guided percutaneous marking and virtual-assisted lung mapping (VAL-MAP).MethodsWe investigated 215 patients who underwent curative wedge resection for malignant tumors using CT-guided localization or VAL-MAP from 1998 to 2018 in our institute. Each resected nodule was assessed for successful resection, which was defined as complete resection with adequate margins.ResultsOne-hundred-and-nineteen patients with 153 nodules were included. The overall successful resection rate was 87.6%. The successful resection rate was significantly lower for nodules with intraoperative adhesion than those without intraoperative adhesion (75.0% vs. 90.1%; P=0.034), and for tumors requiring deep resection margins (>31 mm) than those requiring shallow margins (≤31 mm) (76.7% vs. 94.6%; P=0.002). Although the successful resection rate for nodules resected using CT-guided localization was significantly lower in cases with versus without intraoperative adhesion (54.5% vs. 86.7%; P=0.048), the successful resection rate for nodules resected using VAL-MAP was not influenced by the presence or absence of adhesion (85.7% vs. 93.4%; P=0.491).ConclusionsA requirement for deeper resection and the presence of intraoperative adhesion were limitations of preoperative lung surface localization for curative pulmonary wedge resection.