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Application of microcoil localization in thoracoscopic resection of small pulmonary nodulesA
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QIU
Duwang
1
Wei
JIANG
2
CHEN
Defu
2
SU
Lei
1
Zhenjia
LI
3
Luan
Xiaomei
1
GAO
Fei
1,4✉
Emailgf-gr@163.com
1
Center of Imaging Intervention
Jinan Zhangqiu District People’s Hospital affiliated to Jining Medical University
250200
Jinan
China
2
Cardiothoracic surgery
Jinan Zhangqiu District People’s Hospital affiliated to Jining Medical University
250200
Jinan
China
3
Center of CT Intervention
Shandong Provincial Hospital
250021
Jinan
China
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Jinan Zhangqiu District People’s Hospital, Jining Medical University
No. 1920, Huiquan Road, Zhangqiu District
Jinan City
Shandong Province
QIU Duwang1, JIANG Wei2, CHEN Defu2, SU Lei1, LI Zhenjia3, Luan Xiaomei1, GAO Fei1*
1Center of Imaging Intervention,Jinan Zhangqiu District People’s Hospital affiliated to Jining Medical University, Jinan 250200, China
2Cardiothoracic surgery, Jinan Zhangqiu District People’s Hospital affiliated to Jining Medical University, Jinan 250200, China
3Center of CT Intervention, Shandong Provincial Hospital, Jinan 250021, China
Corresponding Author:
Gao Fei
Insitute: Jinan Zhangqiu District People’s Hospital affiliated to Jining Medical University
Address: No. 1920, Huiquan Road, Zhangqiu District, Jinan City, Shandong Province
E-mail:gf-gr@163.com
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Abstract
[Abstract] Objective To observe the clinical value of CT-guided microcoil localization in video-assisted thoracoscopic surgery (VATS) for small pulmonary nodules. Methods A retrospective analysis was conducted on 100 patients with small pulmonary nodules who underwent VATS. They were divided into the localization group (n = 50, CT-guided microcoil localization followed by VATS resection) and the non-localization group (n = 50, direct VATS resection). The localization success rate, localization time, and complication rate of the localization group were observed, and the VATS operation time, intraoperative bleeding, conversion to thoracotomy, postoperative drainage, hospital stay, and hospitalization costs were compared between the two groups. Results The localization success rate of the localization group was 98% (49/50), with 6 cases (12%, 6/50) of minor pneumothorax and 8 cases (16%, 8/50) of low-grade bleeding. The average localization time was (15.7 ± 3.5) min. The localization group had significantly better indicators such as operation time, postoperative drainage volume, and hospitalization costs than the non-localization group (P < 0.05). Conclusion CT-guided microcoil localization is simple to operate and has good safety. It helps improve the accuracy and safety of VATS for small pulmonary nodules and has important clinical application value.
[Keywords] microcoil localization; pulmonary nodule; video-assisted thoracoscopic surgery; CT-guided
A
Lung cancer, a disease with the highest incidence and mortality rates among all malignant tumors in China for an extended period, has shown a continuous upward trend in prevalence [1, 2]. With the popularization of low-dose CT screening technology and the application of artificial intelligence (AI) software, the detection rate of suspicious malignant pulmonary nodules has increased, some of which require surgical intervention. Video-assisted thoracoscopic surgery (VATS), known for its minimal invasiveness and rapid postoperative recovery, has become the preferred treatment method [3, 4]. However, small pulmonary nodules are difficult to accurately locate through visual observation or tactile perception during VATS [5, 6]. CT-guided localization can assist thoracic surgeons in accurately locating pulmonary nodules. Currently, common methods include the implantation of metallic markers, medical glue, lipiodol, and tracer marking, among others. Nevertheless, their operability, safety, and effectiveness remain key concerns [6–8]. A
This study explores the effectiveness and safety of CT-guided microcoil localization technology in the thoracoscopic resection of small pulmonary nodules and summarizes relevant localization techniques.1 Materials and Methods
1.1 Study Subjects
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The clinical data of 100 patients with small pulmonary nodules who underwent video-assisted thoracoscopic surgery in XXX Hospital from January 2022 to December 2024 were retrospectively analyzed. The patients were divided into two groups: the microcoil localization group (n = 50, undergoing VATS resection after CT-guided microcoil localization) and the non-localization group (n = 50, undergoing direct VATS resection without preoperative localization). Inclusion criteria: ① Suspicious malignant pulmonary nodules requiring surgical intervention; ② No antiplatelet or anticoagulant drugs were used within 1 week before surgery. Exclusion criteria: ① Severe cachexia; ② Coagulation dysfunction; (3) severe cough or asthma with no relief after symptomatic treatment; ④ Contraindications of CT and thoracoscopic surgery. A
This study protocol was approved by the Institutional Ethics Committee (ethics batch number: 202208). All subjects signed written informed consent.This study received no financial support.1.2 Instruments and Methods(localization of microspring coils)
Chest CT scans were performed using a Philips Brilliance 16-slice large-bore CT scanner with the following parameters: 120 kV tube voltage, 92 mAs tube current, and 5.0 mm slice thickness with equal interval spacing. Thin-section reconstructions were performed when clinically indicated [9]. 18G interventional puncture trocar, Tornado-shaped microcoils (MWCE-18S-7/3-TORNADO, COOK, United States), customized localization grid and disposable interventional procedure kit were used.
The patient was positioned appropriately, and the customized localization grid was placed at the predetermined puncture site. Chest CT scanning was performed to identify the optimal puncture trajectory, with preference given to the shortest possible path while maintaining a needle trajectory perpendicular to the pleural surface. Following standard skin disinfection, draping, and local anesthesia, an 18-gauge introducer needle was advanced incrementally along the predetermined path under CT guidance until the needle tip reached within 1 cm of the target nodule. The microcoil delivery sheath was then inserted through the introducer needle, and the microcoil was deployed at the periphery of the pulmonary nodule using the pusher wire. The entire assembly (introducer needle and sheath) was subsequently withdrawn to the extrapleural space to release the remaining microcoil segment (Fig. 1). CT scan was performed immediately to observe the position of the microcoil, to determine the spatial relationship between the lesion and the microcoil, and to assess for procedure-related complications (e.g., hemorrhage, pneumothorax). After the localization was completed, the patient returned to the ward to await thoracoscopic surgery.
Fig. 1
A 50-year-old female patient presented with a ground glass nodule in the anterior basal segment of the left lower lobe, with a maximum diameter of 6mm. Microcoil localization was performed before thoracoscopic resection. A: In the right lateral position, chest CT showed nodules in the left lower lobe of the lung (red arrow) and positioning grid; B Microcoils were implanted near nodules (red arrows are nodules, green arrows are microcoils); C Microcoil positioning after operation, the position was good, no obvious pneumothorax and bleeding; D. The end of the microcoil was exposed outside the pleura during thoracoscopic surgery (red circle); E Microinvasive adenocarcinoma was diagnosed by postoperative pathology (HE staining, X100).
1.3 Instruments and Methods(thoracoscopic surgery)
The STORZ full HD thoracoscopic system was utilized for the procedure. Following successful general anesthesia induction, the patient was placed in the lateral decubitus position with the unaffected side down. After successful general anesthesia, the patient was routinely disinfected and covered with a cloth. A single-hole incision of about 3cm in length was made at the 4–6 intercostal axillary line of the affected side. The skin, subcutaneous and muscular layers were cut through the chest, the thoracoscope was then introduced for nodule localization(In the localization group, the microcoil position guided nodule identification; In the non-localization group, nodules were identified through visual inspection and manual palpation ). A disposable linear suture device was used to wedge resection of the nodule and the surrounding lung tissue 2cm from the edge of the nodule. The resected specimen was immediately sent for intraoperative frozen section analysis. Subsequent surgical management (extended resection or lymph node dissection) was determined based on the pathological findings. After the operation, a closed thoracic drainage tube was routinely placed and the chest was closed by layer-by-layer suture. This was followed by transfer to the intensive care unit, and postoperative drainage volume was continuously monitored.
1.4 Observation indicators
The basic data of the two groups were recorded, including gender, age, nodule location (upper lobes and right middle lobe were classified as upper lung, lower lobes were classified as lower lung), maximum diameter, nodule type (solid or subsolid), the shortest distance from nodule to pleura, thoracoscopic operation time, intraoperative blood loss, whether to convert to thoracotomy, number of lymph node dissection, postoperative drainage, hospitalization time, hospitalization cost, and postoperative pathological data Materials and so on. The statistical indicators of the positioning group included: Localization success rate (CT scan confirmed that the tip of the coil was within 1cm of the small pulmonary nodule; The tail outside the pleura was regarded as successful localization), localization time (time interval from the first CT image to the last CT image), pneumothorax (small, medium and large pneumothorax were defined by 30% and 60% of lung compression volume), hemorrhage (bleeding grading evaluation [10]), severe pleural reaction, whether the microcoil was dislocated or not, radiation dose during localization, etc.
1.5 Statistical Analysis
Statistical analyses were performed using SPSS software (version 26.0, IBM Corp). Continuous variables with normal distribution were expressed as mean ± standard deviation (SD) and compared using Student's t-test. Non-normally distributed continuous variables were presented as median (interquartile range) and analyzed with the Mann-Whitney U test. Categorical variables were compared using either the chi-square test or Fisher's exact test, as appropriate. A two-tailed P-value < 0.05 was considered statistically significant.
2 Results
2.1 Comparison of Baseline Characteristics Between Groups
No statistically significant differences were observed in clinical characteristics (gender, age, nodule location, nodule type, pathological type, etc.) between the two groups (all P > 0.05), as shown in Table 1. The maximum diameter of nodules in the localization group (1.15 ± 0.4 cm) was smaller than that in the non-localization group (1.38 ± 0.4 cm), with this difference reaching statistical significance (P = 0.008 < 0.05).
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Group
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gender
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age
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Nodule location
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The maximum diameter
(cm)
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Nodule type
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Pathological type
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|---|---|---|---|---|---|---|---|---|---|---|
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Men
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Female
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Upper lung
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Lower lung
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Solid
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Subsolid
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Benign
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Malignant
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|||
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localization group(n = 50)
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17
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33
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57.5 ± 8.4
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32
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18
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1.15 ± 0.4
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9
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41
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4
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46
|
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non-localization group(n = 50)
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22
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28
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60.8 ± 11.1
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28
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22
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1.38 ± 0.4
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13
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37
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9
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41
|
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t/c2value
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1.051
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-1.692
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0.667
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-2.722
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0.932
|
2.210
|
||||
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P value
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0.305
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0.094
|
0.414
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0.008
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0.334
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0.137
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||||
2.2 Microcoil Localization and Associated Complications
In the localization group, the success rate of localization was 98% (49/50), and one case of microcoil migration into the extrapleural space was identified during thoracoscopy. The average positioning time was (15.7 ± 3.5) minutes. Minor pneumothorax occurred in 6 cases (6/50, 12%), and no case required closed thoracic drainage. There were 8 cases of low-grade hemorrhage (8/50, 16%), and the bleeding range was within 2cm from the needle tract. No cases of significant intrapulmonary hemorrhage or severe pleural reaction were observed.
2.3 Comparative Analysis of Postoperative Outcomes Between Groups
There were no significant differences in intraoperative blood loss (P = 0.065), number of harvested lymph nodes (P = 0.343), postoperative hospital stay (P = 0.313) and conversion to thoracotomy (P = 1.000) between the two groups. One patient in the non-localization group was converted to thoracotomy. There were significant differences in operation time (P = 0.000), postoperative drainage (P = 0.000) and hospitalization cost (P = 0.0005) between the two groups. See Table 2 and Fig. 2.
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Group
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Time
(min)
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Peroperative bleeding(mL)
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Drainage after operation(mL)
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Lymph nodes dissected
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Hospital stays
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Hospitalization costs
(ten thousand yuan)
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Conversion to thoracotomy
|
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|---|---|---|---|---|---|---|---|---|
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localization(n = 50)
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62(50,95)
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40(20,50)
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200(100,270)
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2(0,3)
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10(9,13)
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3.69 ± 0.42
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0
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50
|
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non-localization(n = 50)
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105(73,136)
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50(42.5,50)
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300(200,500)
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2(0,5)
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11(9,13)
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3.97 ± 0.48
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1
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49
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Statistical value
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-4.135
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-1.847
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-4.225
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-0.948
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-1.009
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-2.782
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----
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|
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P value
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0.000
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0.065
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0.000
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0.343
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0.313
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0.005
|
1.000
|
|
Fig. 2
shows a comparison diagram of thoracoscopic operation time, postoperative drainage volume and hospitalization cost between the two groups of patients
3 Discussion
Accurate preoperative localization of small pulmonary nodules remains clinically significant, as these lesions are often difficult to visualize or palpate during VATS procedures. Effective localization techniques enable thoracic surgeons to precisely identify target nodules, thereby facilitating successful wedge resections. At present, CT-guided percutaneous localization is the most common preoperative localization method. The commonly used markers include metal markers (such as Hook-wire positioning needle, metal spring coil, etc.), liquid markers (medical glue, lipiodic oil, tracer, methylene blue, indocyanine green, etc.). These methods are still the focus of attention in terms of operability, safety and effectiveness [7, 8]. It has been reported in previous literature [11, 12] that Hook-wire positioning needle may cause obvious discomfort or pain in patients, and there is a risk of dislodging. Liquid markers may cause irritating cough in patients, and lipiodiol may penetrate into blood vessels and cause pulmonary embolism. Methylene blue and indocyanine green need VATS surgery within 3 hours due to rapid diffusion. The fusion of medical glue with pulmonary nodules may affect the accuracy of postoperative pathological results. In contrast, microcoils have been widely used in vascular embolization therapy because of their good histocompatibility and flexibility, without causing obvious damage to the lung parenchyma and pleura after implantation or even falling off.
The microcoil localization technique demonstrated excellent operational feasibility in our study, with a mean procedural time of only 15.7 ± 3.5 minutes - significantly shorter than that reported by Kha et al. and Mayo et al [13, 14].
The placement operation is completed after 3–4 low-dose local CT scans. The puncture technique is summarized as follows: after making sure that the needle reaches within 1cm of the edge of the small pulmonary nodule (pay attention to avoid puncture into the nodule to prevent tumor dissemination and postoperative imaging pathology [15]), release the distal coil (generally more than 3cm), and directly withdraw the needle outside the pleura (measure the skin-to-pleura distance) to release the proximal coil. Finally, the needle and coil insertion device were withdrawn simultaneously, and no additional CT scan was required to minimize radiation exposure to the patient. At the end of the localization, CT was reviewed to confirm that the microcoil marked both the nodule and the pleura. In addition, the puncture path should be designed as perpendicular to the pleura as possible, and the trachea, blood vessels and interlobar pleura should be avoided to reduce the risk of complications.
The artificial fibrous filaments coating the microcoil surface enhance frictional properties, enabling secure anchoring within the pulmonary parenchyma and effectively reducing risks of migration or dislodgement. The success rate of localization in 50 patients was as high as 98%, and all positioning patients completed VATS surgery on the same day. Thoracoscopic visualization revealed a single case (2%) of microcoil displacement into the extrapleural space, which retrospective analysis attributed to insufficient deployment depth (only 10 mm from the pleura). The front end of the microcoil should be fixed at its depth to ensure its stability, and the interval time between positioning and VATS should be shortened as far as possible [7]. The microcoil has good flexibility and high safety. CT scan after positioning in this study showed a small amount of pneumothorax (6/50, 12%) and bleeding (8/50, 16%), which were similar to those reported in the literature [7, 8], and no further treatment was needed for pneumothorax and bleeding. Absence of clinically significant pain or pleural reactions in all cases.
The results of this study show that the maximum diameter of pulmonary nodules in the microcoil localization group is smaller than that in the non-localization group. For smaller nodules, it is more difficult to find during VATS, so preoperative localization is more important. The results of this study showed that the localization group not only significantly shortened the operation time, but also reduced the postoperative drainage volume and medical costs, so as to effectively relieve the economic pressure of patients. It is worth noting that this technology achieved precise lung tissue resection and preserved the respiratory function of patients to the greatest extent on the basis of ensuring the complete resection of pulmonary nodules and safe resection margins. No statistically significant intergroup differences were observed in the length of hospital stay and intraoperative blood loss. One patient in the non-localization group was converted to thoracotomy due to unsuccessful nodule identification, a difference not reaching statistical significance (p = 1.00), potentially reflecting the study's limited sample size. In the future, larger scale studies are needed to further verify these results. In addition, follow-up studies will introduce other positioning methods for comparison and explore the value of the combination of the two methods. In conclusion, CT-guided microcoil localization of small pulmonary nodules is easy to operate and safe. The simultaneous marking of nodules and pleura by microcoil can effectively guide thoracoscopic resection of small pulmonary nodules, and can significantly improve the accuracy and safety of thoracoscopic resection of small pulmonary nodules, which has important clinical value.
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Author Contribution
QIU Duwang participated in the entire research process and was responsible for writing the main content of the manuscript. JIANG Wei, CHEN Defu and SU Lei were involved in the collection of medical records and the interventional surgery process. LI Zhenjia was responsible for reviewing and modifying the experimental plan. Luan Xiaomei was in charge of polishing the text and creating the charts. GAO Fei was responsible for designing the experimental approach and revising the article.
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Data Availability
Data is provided within the manuscript or supplementary information files
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