Computer tomography guided thoracoscopic resection of small pulmonary nodules in the hybrid theatre

Ioannis Karampinis, Nils Rathmann, Michael Kostrzewa, Steffen J. Diehl, Stefan O. Schoenberg, Peter Hohenberger, Eric D. Roessner

Abstract
Thoracic surgeons are currently asked to resect smaller and deeper lesions which are difficult to detect thoracoscopically. The growing number of those lesions arises both from lung cancer screening programs and from follow-up of extrathoracic malignancies. This study analyzed the routine use of a CT-aided thoracoscopic approach to small pulmonary nodules in the hybrid theatre and the resulting changes in the treatment pathway.

Introduction
The introduction of lung cancer screening and the implementation of structured follow-up programs for solid malignancies have led to a rapid increase in the number of small pulmonary nodules detected in CT scans [1, 2]. Parallel to that, the spread of the thoracoscopic surgery has given the medical community access to pulmonary lesions avoiding the morbidity associated with the thoracotomy [3].

Both the lung cancer screening programs and the guidelines of the Fleischner Society focus on incidentally detected pulmonary nodules and less on lesions diagnosed during follow-up CT scans in cancer patients [4]. In oncological patients, more than two lesions occurring newly in the lung are considered to represent metastases.

Materials and methods
The procedure was conducted under general anaesthesia. After intubation and ventilation the patient was turned to a lateral decubitus position and the surgical field was prepared for the thoracoscopic access. The C-arm cone beam CT (CBCT) was then performed according to the protocol published earlier [10]. Using the inherent laser navigation system of the multiaxis C-arm system (Syngo X-Workplace; Siemens Healthcare GmbH, Germany) an 18-gauge marking wire with a spiral end (Somatex Lung Marker; Somatex Medical Technologies GmbH, Germany) was positioned. After lesion-marking a repeat CBCT scan was performed to verify the correct position of the wire and detect potential complications.

Results
50 patients (22 males, 28 females; mean age 63.1 years, SD 10.6) with a total of 52 lesions were included to this study. The histopathological findings of the resected specimens are summarized on Table 1. For detailed characteristics of the patients, the histopathology and the procedure see the online supplementary material (Tables 2 and 3 in S1 File). The mean diameter of the lesions resected (for the calculation the longest diameter of the lesion was measured in the pre-interventional CT scan) was 8.41 mm (SD 4.27 mm). The mean lesion depth measured in the pre-interventional CT scan was 18.3 mm (SD 10.3). The mean depth to diameter ratio was 2.45 (SD 1.38). Lesions with a depth to diameter ratio under 1 were only GGOs without solid components.

Discussion
Due to the high imaging quality and the low radiation exposure, the indication for low-dose CT scans has expanded both to the screening of primary lung cancer and to the follow-up of other malignancies. This will certainly lead to a further increase in the detection rate of small, nonspecific pulmonary lesions. The main problem resulting is the potential overtreatment caused by the invasive procedures performed due to falsely positive findings on chest CT scans as the NLST trial confirmed [8]. On the other hand, resecting lesions that prove to be metastases is probably beneficial for the patient, since improved survival has been shown following resection of pulmonary metastases. Furthermore, the current trend in the treatment of oligometastatic tumors is towards more aggressive surgical approaches. As a consequence, it is essential to find the optimal balance between oncological benefit and overtreatment of patients with small pulmonary nodules.

Conclusion
In this study 40% of the patients underwent surgery for a lesion that was proven to be histologically different from what the MDT was expecting, including 9 new cases of primary lung cancer, 3 patients with tuberculosis requiring treatment and 9 other benign lesions. It is therefore reasonable to suggest that the CATS method can be considered for the resection of small pulmonary lesions, which require histological confirmation and cannot be accessed in a less invasive way.

Citation: Karampinis I, Rathmann N, Kostrzewa M, Diehl SJ, Schoenberg SO, Hohenberger P, et al. (2021) Computer tomography guided thoracoscopic resection of small pulmonary nodules in the hybrid theatre. PLoS ONE 16(11): e0258896. https://doi.org/10.1371/journal.pone.0258896

Editor: Hyun-Sung Lee, Baylor College of Medicine, UNITED STATES

Received: April 19, 2021; Accepted: October 7, 2021; Published: November 3, 2021

Copyright: © 2021 Karampinis et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: No funding was received for this study.

Competing interests: IK has no competing interests to declare. NR has received travel grands from Siemens Healthcare GmbH. The ICRN has research agreements with Siemens Healthcare GmbH. MK has no competing interests to declare. SJD has no competing interests to declare. The ICRN has research agreements with Siemens Healthcare GmbH. SOS has no competing interests to declare. The ICRN has research agreements with Siemens Healthcare GmbH. PH has no competing interests to declare. EDR has received travel grands from Siemens Healthcare GmbH. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

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