Intraoperative transbronchial metallic coil marking guided by mobile 3D C-arm for resection of a small peripheral lung lesion

Introduction

Recent studies have established the value of sublober resection of small early-stage lung cancer lesions (1,2). These results, coupled with the increased detection of small pulmonary lesions through the wide-spread use of computed tomography (CT) imaging, imply an increasing need for precise localization of small pulmonary nodules resected via video-assisted thoracic surgery (VATS). Various markers and placement methods have been reported for intraoperative marking and localization of small lesions for VATS (3). At our institution, we adopted a metallic coil as a marker for precise localization, with the coil deployed through a transbronchial rather than a percutaneous approach for increased safety (4,5). Our original marking method was performed under local anesthesia in an interventional radiology suite equipped with CT, several days before VATS. Recently, we modified our approach to perform marking and VATS under general anesthesia successively on the same day in a hybrid operating room (HOR) equipped with cone-beam CT (CBCT). Despite its advantages, the modified approach requires the availability of a suitable HOR, which limits the approach’s accessibility. The recent availability of CBCT imaging on 3D mobile C-arms makes it possible to perform a similar approach in any conventional operating room. Similar to standard mobile C-arm systems, the C-arm model used can generate 2D fluoroscopic X-ray images through a 30 cm × 30 cm flat-panel X-ray detector. Moreover, it capable of generating 3D cone-beam CT images by automatically rotating the gantry around the patient body in arc of 196 degrees in the duration of 30 seconds. During rotation, the C-arm collects 400 X-ray projection images that are reconstructed automatically on the C-arm workstation in approximately 10 seconds to generate a 3D CBCT image of 16×16×16 cm³ size and 512×512×512 pixels. The mobile C-arm is compact and it can be utilized in any operating room. We report our first experience with intraoperative transbronchial metallic coil marking followed by VATS under mobile 3D C-arm guidance for a case series of three small peripheral lung lesions. We present this article in accordance with the SUPER reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-951/rc).

Preoperative preparations and requirements

Indications for the transbronchial metallic coil marking include (I) peripheral pulmonary lesions measuring 10 mm or less that are scheduled for VATS wedge resection, (II) deeply located nodules between 0 and 30 mm from the pleural surface and (III) ground glass nodules (GGNs) without pleural change. In patients whose bronchi do not reach the vicinity of the target lesion, this method may not be applicable because it is difficult to place the coil at the appropriate site. Therefore, the relationship between the bronchi and the target lesion must be carefully confirmed on preoperative CT images. Since 2003, transbronchial metallic coil marking method has been performed on more than 300 patients at our institution, of which the most recent 80 cases were performed under general anesthesia in a HOR. Most recently, we performed transbronchial metallic coil marking guided by mobile 3D C-arm in a conventional operating room. In this report, we present three cases in which this method was used. This study was performed in accordance with the Declaration of Helsinki (as revised in 2013) and was approved by the Committee for Medical Ethics of Tokushima University Hospital (No. 3672). Written informed consent was obtained from the participants for the publication of this surgical technique and accompanying images and videos.

A man in his 70s with a history of surgery for stage IIIA rectal cancer three years ago was referred to our department. Follow-up CT images have shown a slowly growing nodule in the right upper lobe of the lung (Figure 1A). A solitary metastatic lung tumor was suspected, and VATS wedge resection was scheduled. Since it was expected that the lesion would be difficult to locate intraoperatively, we decided to perform transbronchial metallic coil marking prior to the VATS wedge resection.

Figure 1 Preoperative CT and images during intraoperative transbronchial metallic coil marking guided by mobile 3D C-arm. (A) CT showing an 11-mm nodule in the right upper lobe. (B) The mobile 3D C-arm used during the marking procedure. This image is published with the patient’s consent. (C) A fluoroscopic image showing the installed metallic coil (arrow) through a bronchoscope. (D) Cone-beam CT showing a metallic coil (arrow) within the lesion. CT, computed tomography.

Step-by-step description

Setting before marking

The patient was placed in a supine position and intubated with a single lumen tube under general anesthesia in a conventional operating room. Since fluoroscopy and CBCT are used during the procedure, it is necessary to use a radiolucent surgical carbon patient bed with no metal parts. The patient’s upper limbs were positioned along the trunk, and the position of the mobile 3D C-arm (Cios Spin; Siemens Healthineers AG, Forchheim, Germany) was carefully adjusted so avoid contact with the patient’s body during C-arm was rotation. Additionally, equipment such as the bronchoscope system must be located where it will not interfere with the rotation of the C-arm.

Transbronchial metallic coil marking guided by mobile 3D C-arm

After an ultrathin video-bronchoscope (type XP260F; Olympus, Tokyo, Japan) was inserted into an objective bronchus guided with virtual bronchoscopic navigation, a coil-feeding microcatheter (FasTracker-325; Boston Scientific, Tokyo, Japan) was inserted through the bronchoscope’s working channel, and the tip of the catheter was adjusted using C-arm fluoroscopy guidance. CBCT images rendered by the mobile 3D C-arm were used to locate the tip of the microcatheter and metallic coil (Figure 1B, Video 1). CBCT image acquisition requires rotation of the X-ray source and detector 196 degrees around the patient’s thorax over a period of 30 seconds, during which a total of 400 X-ray projection images are acquired. The projection images are automatically reconstructed on the C-arm’s workstation in approximately 10 seconds. CBCT was acquired with breathing stopped, and airway pressure at 20 cmH₂O. After confirming that the tip of the microcatheter reached the lesion on multi-planar reconstructions of the CBCT (axial, coronal, sagittal), a fibered platinum coil (Boston Scientific, Tokyo, Japan) was positioned under fluoroscopic guidance (Figure 1C). A second CBCT image was acquired to confirm the deployed metallic coil location relative to the lesion (Figure 1D). Metal artifact reduction feature on the mobile C-arm was used to suppress artifacts from the metallic coils. All lesions were clearly visible on the CBCT images.

VATS wedge resection under C-arm fluoroscopic guidance

The patient was re-intubated with a double lumen tube and placed in the left lateral decubitus position. The thoracic cavity was explored with 3-port VATS. The lesion could not be identified by visual inspection or manual palpation. Through fluoroscopic 2D imaging on the mobile C-arm, the location of the metallic coil was identified. The nodule with metallic coil was grasped with pulmonary forceps and resected with endostaplers under fluoroscopic guidance (Figure 2A,2B, Video 2). The lung tissue where the coil is located was manipulated with the forceps as few times as possible to reduce the risk of coil migration. To ensure complete lesion excision, once the coil was captured within the ring of the pulmonary forceps, the forceps was not released until the wedge resection was completed.

Figure 2 Images during VATS pulmonary wedge resection. (A) An intraoperative fluoroscopic image showing the metallic coil (arrow) grasped with pulmonary forceps. (B) Macroscopic findings of the resected specimen showing a whitish tumor and the metallic coil (arrow). VATS, video-assisted thoracic surgery.

Postoperative considerations and tasks

The postoperative course was uneventful, and the patient was discharged five days after the operation. The resected lesion was diagnosed as a lung metastasis of rectal cancer on postoperative pathological examination.

Coil marking was performed on two additional small pulmonary lesion cases via the same approach, for a total of three cases marked with metallic coils and resected under mobile 3D C-arm guidance. All lesions were resected with sufficient margins (Figure 3) and no recurrence was noted during follow-up (26–28 months).

Figure 3 Characteristics and results of 3 cases of coil marking guided by mobile 3D C-arm. CT, computed tomography.

Tips and pearls

Placing the metallic coil as close as possible to the lesion allows accurate identification of the lesion during surgery. Particularly in the case of a lesion far from the pleura, the marking position must be placed very close to the lesion. If the distance between the coil and the lesion is 1 cm or more, it may be difficult to secure a sufficient resection margin. Therefore, it is important to sufficiently confirm the bronchial route to the lesion using virtual bronchoscopic navigation before marking. CBCT images provide confirmation of the distance between the catheter tip and the lesion. When the catheter tip is far from the lesion, it is necessary to adjust the tip position with reference to the CBCT images.

Discussion

Various marking methods have been reported for intraoperative identification and resection of small lung lesions (3). We previously reported a transbronchial metallic coil marking method performed in a CT-equipped interventional radiology suite several days before surgery (4,5). Recently, the procedure from marking to VATS has been performed sequentially in a HOR under general anesthesia at our institution. The current report illustrates that a similar workflow is possible using a CBCT-capable mobile 3D C-arm in any conventional operating, thereby making the approach accessible to hospitals without an HOR. CBCT metal artifact reduction feature may help avoid obscuring the lesion by artifacts from the nearby metal coils used for lesion marking. Recent reports have indicated that the quality of mobile C-arm CBCT imaging is also adequate to support transbronchial interventions (6,7). Single-step localization and resection of small pulmonary nodules using a mobile 3D C-arm with a percutaneous approach similar to our method has been reported (7). The authors used indocyanine green for superficial lesions and metallic coils or hook wires for deeply located nodules.

The presented transbronchial metallic coil marking method has several advantages over other marking methods. First, the transbronchial approach has a lower risk of complications such as pneumothorax and air embolism, compared with a percutaneous approach (4,5). The incidence of pneumothorax associated with the percutaneous approach has been reported to be 7.5–40% (8); therefore, the transtracheal approach is safer, especially for emphysematous lungs or lungs with structural change. Other complications of the percutaneous approach include pulmonary parenchymal hemorrhage (13.9–36%) and subcutaneous emphysema (5%) (8). Air embolism is an extremely rare however potentially fatal complication (9). Moreover, pleural dissemination or needle tract implantation is possible adverse event with a percutaneous approach. Second, a metallic coil provides precise pinpoint localization, unlike liquid dyes, which sometimes spread to the surrounding lung parenchyma, especially when used in an emphysematous lung.

Although it has been reported that the radiation exposure of CBCT is equivalent to that of low-dose CT (10), efforts should be made to minimize the number of CBCT scans during this procedure in order to reduce radiation exposure for patients and surgeons. To further reduce radiation exposure for surgeons, the use of bronchoscope holders and X-ray radiation shielding screens is recommended. Other disadvantage of our method includes the high cost of the metallic coils and microcatheters. They cost about $500 in US dollars. The technique of advancing an ultrathin bronchoscope to the peripheral target bronchus is considered a difficult procedure for surgeons who are not familiar with bronchoscopy. One solution would be to use virtual bronchoscopy navigation, but it would be more effective if there are opportunities for training in bronchoscopy techniques. The pros and cons of our method compared to other common techniques are presented in Table 1.

For reference, we present the results of transbronchial metallic coil marking in 80 cases performed in the HOR at our hospital. The median lesion size was 11.5 mm, and the median distance from the lesion to pleura was 8.8 mm. About 70% of the lesions were either pure GGN or part-solid GGN lesions. In all cases, the metallic coil could be placed at the target site, and the median time for marking was 22.5 minutes. The distance between the metallic and the lesion was 4.3 mm, and all microcoils were useful to resect the lesions with sufficient margins. The median time for wedge resection was 38 minutes. There were no complications with this marking method. In recent years, this marking method has been used in combination with not only 3-port VATS but also single-port VATS.

Recently, marking procedures performed in HORs have been reported (14,15). Performing marking and VATS successively under general anesthesia in one setting can reduce the physical and psychological stress of patients. However, HORs with CBCT are not available at all hospitals, and are also associated with higher operating costs than conventional operating rooms (16). Mobile 3D C-arms could make this marking procedure accessible to hospitals with a conventional operating room.

Conclusions

The presented mobile 3D C-arm-guided transbronchial metallic coil marking technique followed by VATS wedge resection under fluoroscopic guidance is a one-stop solution for resection of small peripheral pulmonary lesions in a conventional operating room. However, as this method has only been performed in a small number of cases, its efficacy including accurate localization of the metallic coil and the complete resection rate with sufficient surgical margins need to be examined as well as safety in a larger number of cases.

Acknowledgments

The authors would like to acknowledge the support of the Surgical Center of Tokushima University Hospital for this project.

Funding: None.

Footnote

Reporting Checklist: The authors have completed the SUPER reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-951/rc

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-951/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-951/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was performed in accordance with the Declaration of Helsinki (as revised in 2013) and was approved by the Committee for Medical Ethics of Tokushima University Hospital (No. 3672). Written informed consent was obtained from the participants for the publication of this surgical technique and accompanying images and videos.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Saji H, Okada M, Tsuboi M, et al. Segmentectomy versus lobectomy in small-sized peripheral non-small-cell lung cancer (JCOG0802/WJOG4607L): a multicentre, open-label, phase 3, randomised, controlled, non-inferiority trial. Lancet 2022;399:1607-17. [Crossref] [PubMed]
2. Altorki N, Wang X, Kozono D, et al. Lobar or Sublobar Resection for Peripheral Stage IA Non-Small-Cell Lung Cancer. N Engl J Med 2023;388:489-98. [Crossref] [PubMed]
3. Sato M. Precise sublobar lung resection for small pulmonary nodules: localization and beyond. Gen Thorac Cardiovasc Surg 2020;68:684-91. [Crossref] [PubMed]
4. Miyoshi T, Kondo K, Takizawa H, et al. Fluoroscopy-assisted thoracoscopic resection of pulmonary nodules after computed tomography--guided bronchoscopic metallic coil marking. J Thorac Cardiovasc Surg 2006;131:704-10. [Crossref] [PubMed]
5. Toba H, Kondo K, Miyoshi T, et al. Fluoroscopy-assisted thoracoscopic resection after computed tomography-guided bronchoscopic metallic coil marking for small peripheral pulmonary lesions. Eur J Cardiothorac Surg 2013;44:e126-32. [Crossref] [PubMed]
6. Chan JWY, Lau RWH, Chu CM, et al. Expanding the scope of electromagnetic navigation bronchoscopy-guided transbronchial biopsy and ablation with mobile 3D C-arm Machine Cios Spin(®)-feasibility and challenges. Transl Lung Cancer Res 2021;10:4043-6. [Crossref] [PubMed]
7. Hsieh MJ, Chou PL, Fang HY, et al. Single-step localization and excision of small pulmonary nodules using a mobile 3D C-arm. Interact Cardiovasc Thorac Surg 2021;33:885-91. [Crossref] [PubMed]
8. Lin MW, Chen JS. Image-guided techniques for localizing pulmonary nodules in thoracoscopic surgery. J Thorac Dis 2016;8:S749-55. [Crossref] [PubMed]
9. Sakiyama S, Kondo K, Matsuoka H, et al. Fatal air embolism during computed tomography-guided pulmonary marking with a hook-type marker. J Thorac Cardiovasc Surg 2003;126:1207-9. [Crossref] [PubMed]
10. Hohenforst-Schmidt W, Banckwitz R, Zarogoulidis P, et al. Radiation Exposure of Patients by Cone Beam CT during Endobronchial Navigation - A Phantom Study. J Cancer 2014;5:192-202. [Crossref] [PubMed]
11. Sato M, Kobayashi M, Kojima F, et al. Effect of virtual-assisted lung mapping in acquisition of surgical margins in sublobar lung resection. J Thorac Cardiovasc Surg 2018;156:1691-1701.e5. [Crossref] [PubMed]
12. Muñoz-Largacha JA, Ebright MI, Litle VR, et al. Electromagnetic navigational bronchoscopy with dye marking for identification of small peripheral lung nodules during minimally invasive surgical resection. J Thorac Dis 2017;9:802-8. [Crossref] [PubMed]
13. Mariolo AV, Vieira T, Stern JB, et al. Electromagnetic navigation bronchoscopy localization of lung nodules for thoracoscopic resection. J Thorac Dis 2021;13:4371-7. [Crossref] [PubMed]
14. Anayama T, Hirohashi K, Okada H, et al. Simultaneous cone beam computed tomography-guided bronchoscopic marking and video-assisted thoracoscopic wedge resection in a hybrid operating room. Thorac Cancer 2019;10:579-82. [Crossref] [PubMed]
15. Chao YK, Leow OQY, Wen CT, et al. Image-guided thoracoscopic lung resection using a dual-marker localization technique in a hybrid operating room. Surg Endosc 2019;33:3858-63. [Crossref] [PubMed]
16. Patel S, Lindenberg M, Rovers MM, et al. Understanding the Costs of Surgery: A Bottom-Up Cost Analysis of Both a Hybrid Operating Room and Conventional Operating Room. Int J Health Policy Manag 2022;11:299-307. [PubMed]