Getting closer: localization techniques for small pulmonary nodules

Surgical resection of small pulmonary nodules has increased due to the adoption of lung cancer screening. Despite careful review of preoperative imaging, when nodules are small (<10 mm), deep (>10 mm from pleural surface) or predominantly ground glass, they can be difficult to localize thoracoscopically, potentially requiring conversion to thoracotomy or removal of additional lung parenchyma (1). An accurate and safe approach for nodule localization is essential, as an adequate resection margin has been associated with risk of recurrence and survival following resection for early-stage non-small cell lung cancer (2,3).

Many techniques have been utilized for nodule localization, including pre-procedural (e.g., percutaneous or bronchoscopic placement of a metallic marker or dye) or intra-procedural approaches (e.g., real-time imaging with thoracoscopic ultrasound). However, the most commonly used techniques, such as percutaneous hookwire placement, require an additional procedure which is occasionally associated with complications such as bleeding or pneumothorax. In some centers, a hybrid operating room may improve time and cost of nodule localization, but these are not widely available (4). Studies directly comparing localization techniques are limited and no approach has shown clear superiority (5,6). Thus, the approach is largely dependent on surgeon preference and available resources.

In their article, Pang and colleagues describe a novel localization technique for small pulmonary nodules during thoracoscopic resection which is based on anatomic landmarks identified on the pre-procedure computed tomography (CT) scan (7). Using measured distances from fixed anatomic points in the chest, they created a pleural dye marking during a recruitment maneuver and this “tattoo” was used to localize the nodule. They retrospectively report their technique in 120 patients with a successful localization in an impressive 98.5% of cases. Median localization time was 11 minutes (range, 8–14 minutes), which compares favorably to previously described techniques. Finally, and perhaps most importantly, there were no localization-related complications.

In some respects, localization based on anatomic landmarks during thoracoscopic resection provides an optimal solution. First, it achieves localization with high success. Second, nodule localization and resection are performed during one procedure, and is not associated with a risk of pleural injury. Finally, the localization time is short and requires little additional equipment.

While the technique is logical, selecting the appropriate landmarks using soft tape measures and lung inflation/deflation is potentially imprecise and it is not clear how broadly the technique can be applied. Curiously, the median depth of these nodules was less than a centimeter, prompting the question of whether these nodules even required localization. Furthermore, the dimensions of the wedge resections were not reported, partially negating the importance of accurate localization if large wedge resections were performed. This is particularly important for the 9% of patients in their cohort with benign disease that may have avoided surgery with an alternative management strategy such as bronchoscopic biopsy. Nevertheless, the results presented here are notable.

Techniques for nodule localization continue to evolve. For example, the use of robotic-assisted bronchoscopy platforms, potentially in combination with cone-beam CT guidance, have reported promising early results for the diagnosis of peripheral pulmonary nodules (8,9). Importantly, these platforms allow for single anesthesia events, in which biopsy of a pulmonary nodule is performed prior to resection in a single operating room. Additionally, intra-operative molecular imaging holds potential for in vivo imaging of pulmonary nodules without a separate localization procedure and is being investigated in multiple cancer types (10).

In summary, Pang and colleagues provide more evidence that the surgeon may be able to perform accurate localization and resection during a single thoracoscopic procedure. Their technique had a high success rate in this retrospective cohort and was not associated with any localization-related complications. Further prospective studies are needed to evaluate the generalizability and learning curve of this approach, and to directly compare different approaches for nodule localization.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Journal of Thoracic Disease. The article did not undergo external peer review.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-22-908/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.

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. Saito H, Minamiya Y, Matsuzaki I, et al. Indication for preoperative localization of small peripheral pulmonary nodules in thoracoscopic surgery. J Thorac Cardiovasc Surg 2002;124:1198-202. [PubMed]
2. Wolf AS, Swanson SJ, Yip R, et al. The Impact of Margins on Outcomes After Wedge Resection for Stage I Non-Small Cell Lung Cancer. Ann Thorac Surg 2017;104:1171-8. [Crossref] [PubMed]
3. Mohiuddin K, Haneuse S, Sofer T, et al. Relationship between margin distance and local recurrence among patients undergoing wedge resection for small (≤2 cm) non-small cell lung cancer. J Thorac Cardiovasc Surg 2014;147:1169-75; discussion 1175-7. [Crossref] [PubMed]
4. Zhao ZR, Lau RWH, Ng CSH. Hybrid Theater and Uniportal Video-Assisted Thoracic Surgery: The Perfect Match for Lung Nodule Localization. Thorac Surg Clin 2017;27:347-55. [Crossref] [PubMed]
5. Park CH, Han K, Hur J, et al. Comparative Effectiveness and Safety of Preoperative Lung Localization for Pulmonary Nodules: A Systematic Review and Meta-analysis. Chest 2017;151:316-28. [Crossref] [PubMed]
6. Chao YK, Pan KT, Wen CT, et al. A comparison of efficacy and safety of preoperative versus intraoperative computed tomography-guided thoracoscopic lung resection. J Thorac Cardiovasc Surg 2018;156:1974-83.e1. [Crossref] [PubMed]
7. Pang D, Shao G, Zhang J, et al. 3D localization based on anatomical landmarks in the treatment of pulmonary nodules. J Thorac Dis 2022;14:3133-44. [Crossref]
8. Chen AC, Pastis NJ Jr, Mahajan AK, et al. Robotic Bronchoscopy for Peripheral Pulmonary Lesions: A Multicenter Pilot and Feasibility Study (BENEFIT). Chest 2021;159:845-52. [Crossref] [PubMed]
9. Kalchiem-Dekel O, Connolly JG, Lin IH, et al. Shape-Sensing Robotic-Assisted Bronchoscopy in the Diagnosis of Pulmonary Parenchymal Lesions. Chest 2022;161:572-82. [Crossref] [PubMed]
10. Kennedy GT, Azari FS, Bernstein E, et al. Targeted Intraoperative Molecular Imaging for Localizing Nonpalpable Tumors and Quantifying Resection Margin Distances. JAMA Surg 2021;156:1043-50. [Crossref] [PubMed]