Abstract
Objectives:
To evaluate the effect of the position of microcoil proximal end on the incidence of microcoil dislocation during CT-guided microcoil localization of pulmonary nodules (PNs).
Methods:
This retrospective study included all patients with PNs who received CT-guided microcoil localization before video-assisted thoracoscopic urgery (VATS) resection from June 2016 to December 2019 in our institution. The microcoil distal end was less than 1 cm away from the nodule, and the microcoil proximal end was in the pleural cavity (the pleural cavity group) or chest wall (the chest wall group). The length of microcoil outside the pleura was measured and divided into less than 0.5 cm (group A), 0.5 to 2 cm (group B) and more than 2 cm (group C). Microcoil dislocation was defined as complete retraction into the lung (type I) or complete withdrawal from the lung (type II). The rate of microcoil dislocation between different groups was compared.
Results:
A total of 519 consecutive patients with 571 PNs were included in this study. According to the position of microcoils proximal end on post-marking CT, there were 95 microcoils in the pleural cavity group and 476 in the chest wall group. The number of microcoils in group A, B, and C were 67, 448 and 56, respectively. VATS showed dislocation of 42 microcoils, of which 30 were type II and 12 were type I. There was no statistical difference in the rate of microcoil dislocation between the pleural cavity group and the chest wall group (6.3% vs 7.6%, x2 = 0.18, p = 0.433). The difference in the rate of microcoil dislocation among group A, B, and C was statistically significant (11.9%, 5.8%, and 14.3% for group A, B, and C, respectively, x2 = 7.60, p = 0.008). In group A, 75% (6/8) of dislocations were type I, while all eight dislocations were type II in group C.
Conclusions:
During CT-guided microcoil localization of PNs, placing the microcoil proximal end in the pleura cavity or chest wall had no significant effect on the incidence of microcoil dislocation. The length of microcoil outside the pleura should be 0.5 to 2 cm to reduce the rate of microcoil dislocation.
Advances in knowledge: :
CT-guided microcoil localization can effectively guide VATS to resect invisible and impalpable PNs. Microcoil dislocation is the main cause of localization failure. The length of microcoil outside the pleura is significantly correlated with the rate and type of microcoil dislocation. Placing the microcoil proximal end in the pleura cavity or chest wall has no significant effect on the rate of microcoil dislocation.
Introduction
The widespread use of chest CT in lung cancer–screening in high-risk population and routine follow-up of oncologic patients has led to frequent detection of solitary pulmonary nodules (PNs). A considerable proportion of PNs is ground glass nodules (GGNs). GGN is referred to as the nodular shadow with slightly increased density and clear boundary, showing the structures of blood vessels and bronchi through the lesions. GGN is a non-specific imaging manifestation, and inflammation, fibrosis, focal atypical hyperplasia, in situ adenocarcinoma, microinvasive adenocarcinoma, invasive adenocarcinoma, and other lesions can be expressed as GGN on CT.1 Compared with solid nodules, the malignant proportion of GGNs remains higher,2 accounting for a rate of 87.2%.3
Video-assisted thoracoscopic surgery (VATS) is adopted to diagnose and treat clinically suspicious malignant PNs. Compared with open thoracotomy, VATS has the advantages of less tissue injury, less complications, better cosmetic results, and shorter postoperative hospital stay.4 However, because small and/or deep PNs might be invisible and impalpable during VATS, more than half of VATS had to get converted to thoracotomy without preoperative localization.5,6 For SPNS smaller than 1 cm in size and greater than 0.5 cm in depth, the probability of conversion to thoracotomy was increased to 63%.5 Preoperative localization can effectively avoid the conversion of VATS to thoracotomy.6,7
A variety of preoperative and intraoperative locating methods have been used.8–18 Various methods can achieve the marking purpose, but each method has their own advantages and disadvantages. Intraoperative B-ultrasound localization is noninvasive, economical, and real‐time. On the other hand, the resolution of B-ultrasound is poor, making it difficult to observe the sub-centimeter GGNs.8 Meanwhile, intraoperative B-ultrasound localization needs complete pulmonary collapse and an experienced operator. Injection of methylene blue and other liquid dyes is simple and economical. Its limitation is that dyes are prone to diffusion, resulting in poor accuracy of localization.9 Surgery should be performed as soon as possible after dye localization to avoid resection expansion. The injection of lipiodol and barium provides inexpensive, safe marking methods. Fluoroscopy guidance is needed during VATS, increasing the radiation of patients and medical staff.10,11 At the same time, Barium can cause inflammation in the surrounding lung tissue and affect the pathological diagnosis of the nodules. Special equipment and radio‐protection are needed when radionuclide localization is performed.12 Injection of colloidal substances can cause cough.13 If the injection site is too close to the lesion or within the lesion, the pathological diagnosis of the lesion may be affected. Hook-wire location is the most commonly used method. It has the advantages of simplicity, accuracy, and effectiveness. But incidence of complications such as pneumothorax and pulmonary hemorrhage, and hook-wire displacement is relatively high.14–17
CT-guided microcoil localization is another common method besides hook-wire location, which has the advantages of high success rate, low major complication, accurate localization, and good patient tolerance.18–28 Although previous studies have shown that localization using microcoil has a lower dislocation rate than using hook-wire,28–31 microcoil dislocation occurs from time to time.25,29–31 Microcoil dislocation includes two types: complete retraction into the lung (the entire microcoil is in the lung) and complete withdrawal from the lung (the entire microcoil is located outside the pleura). Once microcoil dislocation occurs, the surgeon can not accurately remove the nodule under the guidance of the microcoil. At this time, surgeons can occasionally find the nodule by palpation and perform wedge resections. If the pleural puncture point is found, wedge resection can be performed based on the relationship between the pleural puncture point and the nodule. If none of the above efforts is successful, surgeons will be forced to expand the scope of resection or even convert to thoracotomy.
Dislocation is the most common cause of microcoil marking failure. The discovery of controllable factors related to microcoil dislocation can effectively avoid occurrence of dislocation in practice. This study retrospectively analyzed the clinical and imaging data of 519 consecutive patients with PNs who received CT-guided microcoil localization before VATS. The purpose of this study is to evaluate (1) the effect of placing the microcoil proximal end in the pleura cavity and chest wall on the incidence of microcoil dislocation; (2) the correlation between the length of microcoil outside the pleura and the occurrence of microcoil dislocation; (3) the effect of the time interval between microcoil localization and VATS on the incidence of microcoil dislocation.
Methods and materials
Materials
This was a retrospective study. The inclusion criteria were patients with peripheral PNs who received preoperative CT-guided microcoil localization before VATS resection from June 2016 to December 2019 in the department of radiology in our hospital. The criteria of CT-guided microcoil localization for PNs before VATS are as follows: (1) PNs persisted for more than 3 months; (2) PNs might be invisible and impalpable in VATS; and (3) the distance from PNs to pleura was less than 4 cm. The exclusion criteria were patients who had undergone surgery on the same side-of the chest. This study was approved by the Ethics Committee of our hospital.
Marking method
We used the microcoil implantation method described by Mayo19 to mark nodule and pleura at the same time, but made some adjustments to the position of the implanted microcoil. The microcoil distal end was less than 1 cm away from the nodule (within or beyond the nodule), and the microcoil proximal end was outside the visceral pleura (in the pleural cavity or chest wall). All CT-guided microcoil localization were performed by two radiologists who were engaged in CT-guided intervention for 24 and 3 years. The 18-gauge Chiba puncture needle (cook, USA) of 10 cm in length and MWCE-18S-6/2 vascular embolization microcoil set (Tornado, Cook Medical Inc., USA) were used for marking. The embolization microcoil was 7 cm long when straightened and was in diamond shape under the natural state, with a small end (head end) diameter of 2 mm and a big end (tail end) diameter of 6 mm. It was installed in the loading cannula. The loading cannula fits exactly into the 18G Chibe needle lumen. All CT scans were performed on Aquillion-one 16 Slice CT Scanner (Toshiba, Japan) using 100KV, 120mAs, 1.25 mm thickness. It has no CT fluoroscopy function. We used coaxial needle technique of CT puncture to implant the microcoil. The Chiba needle was inserted to the planed position after local anesthesia. Local CT scan confirmed the position relationship between the Chiba needle tip and the nodule to be satisfactory (the distance between the needle tip and the SPN was ≤1.0 cm) (Figures 1a–3a). The Chiba needle inner stylet was then pulled out and the loading cannula with microcoil was inserted into Chiba needle lumen. Slightly pushed the microcoil out of the loading cannula with the stylet, so that a 2 to 3 cm microcoil was deployed into the lung parenchyma where it assumed a tightly coiled helical configuration adjacent to the nodule. The Chiba needle and the loading cannula were retracted from its location adjacent to the nodule to outside the visceral pleural while holding the stylet in place (Figure 1b). This action deployed a straight segment of microcoil along the needle tract, from the nodule to the pleural surface. Then, the Chiba needle and the loading cannula were held stationary and the stylet pushed the remaining microcoil out of the loading cannula. The Chiba needle, empty loading cannula, and stylet were then removed from the chest wall. We usually adjusted the length of the microcoil around the lesion according to the distance from the needle tip to the pleura to realize that the microcoil proximal end was about 1 cm outside the pleura. CT scan of whole lung was performed and axial, sagittal, coronal, and 3D volume-rendered images were used to identify the exact relation of microcoils, nodules, and chest wall (Figures 1c–3b), and to identify any procedure-related complications. If the microcoil position was found to be unsatisfactory, another microcoil was inserted immediately. We initially performed preoperative CT-guided microcoil localization on the day of VATS. If VATS was the first operation of the day, we must complete CT-guided microcoil localization in advance. This caused us to be forced to change our work schedules. After initial exploration, it was found that most of the patients had no obvious discomfort after microcoil localization, and we tried to gradually increase the time interval between microcoil localization and VATS to reduce the effect of microcoil localization on the normal work schedule. Later, we routinely performed CT-guided microcoil localization on Monday, Wednesday, and Friday afternoons. For patients who would undergo VATS wedge resection of PNs on Monday morning, we usually performed microcoil localization on Friday afternoon (The time interval between localization and VATS was more than 60 h).
Figure 1.
A 58-year-old female with 0.9-cm ground glass nodule in right upper lobe underwent CT-guided microcoil localization followed by VATS resection. (a) showed that needle tip passed through the lesion(black arrow); (b) showed the needle tip (black arrow) was retracted to the pleural surface; (c) post-marking CT sagittal reconstruction demonstrated that microcoil proximal end (black arrow) was in chest wall and microcoil distal end passed through the lesion (white arrow). (d) Microcoil proximal end (black arrow) exposed outside the pleura was visualized during VATS.
Figure 2.
65-year-old female with 0.7-cm ground glass nodule in right upper lobe underwent CT-guided microcoil localization followed by VATS resection. (a) showed that needle tip passed through the lesion(black arrow); (b) post-marking CT demonstrated that microcoil proximal end(black arrow) was in the chest wall and minor bleeding(white arrow) in the lung parenchyma around the microcoil; (c) VATS revealed that the microcoil was completely withdrew from the lung.
Figure 3.
55-year-old male with 0.5-cm ground glass nodule in right upper lobe underwent CT-guided microcoil localization followed by VATS resection. (a) showed that needle tip was adjacent to the nodule(black arrow); (b) post-marking CT revealed that microcoil proximal end(black arrow) was in pleural cavity; (c) VATS revealed that the microcoil was fully retracted into the lung. The bleeding points (black arrow) of the pleural puncture was found.
PNs resection by VATS
VATS resection was performed under the guidance of implanted microcoils without the aid of intraoperative fluoroscopy. The procedure of VATS resection under the guidance of implanted microcoils has previously been described in detail.22 During VATS, the surgeon could easily find the microcoil proximal end exposed outside the pleura. Combined with the relation between the lesion and microcoil on post-marking CT, the position of the lesion was determined. Wedge resection for a range more than 2 cm from the edge of the lesion was performed by a cutting suture device. The specimen was immediately opened to confirm that the lesion and the entire microcoil were in the resected specimen. Rapid frozen section examination was performed. Based on the results of frozen section diagnosis, the operation could be ended for patients with benign lesions, metastasis or noninvasive lung cancer. Patients with invasive lung cancer and without contraindications underwent thoracoscopic lobectomy and lymph node dissection or sampling.
Definition, grouping, and statistical analysis
Microcoil dislocation was defined as complete retraction into the lung (type I) or complete withdrawal from the lung (type II) (Figures 2c and 3c). Determined whether there was microcoil dislocation based on the findings of VATS. According to microcoil, proximal end was in the pleural cavity or chest wall on post-marking CT, microcoils were divided into the pleural cavity group and the chest wall group. Two radiologists independently judged the position of microcoil proximal end and measured the length of microcoil outside the pleura. When there were different opinions, a consensus was reached through consultation. The length of microcoil outside the pleura was taken as the mean value of the two surveyors. The length of microcoil outside the pleura was divided into less than 0.5 cm (group A), 0.5 to 2 cm (group B) and more than 2 cm (group C). If multiple microcoils were used for a nodule localization, only the one with satisfactory position was analyzed. Statistical analyses were performed using the SPSS software v.17.0. The general conditions and the rate of microcoil dislocation between different groups were compared. The enumeration data between different groups were compared using chi-square analysis, and the measurement data were compared using independent sample t-test. <i>p-values < 0.05 were considered statistically significant.
Results
The general conditions of patients and nodules
A total of 519 consecutive patients with 571 PNs were included in this study. The general conditions of patients and nodules were shown in Table 1. Kolmogorov-Smirnov test showed that all continuous variables (age, size, depth) were in normal distribution. Normal distribution data were represented by mean ± standard deviation. Patients included 198 males and 321 females. Marked nodules were one in 471 cases, two in 44 cases, and three in 4 cases. The diameter of PNs was 0.92 ± 0.50 cm, and the shortest distance from the lesion to the pleura was 1.38 ± 0.96 cm.
Table 1.
The general conditions of patients and nodules
| Number of patients | 519 |
|---|---|
| Age (year) | 58.85 ± 10.20 |
| Gender | |
| Male | 198 |
| Female | 321 |
| Number of patient-marked nodules | |
| One nodule | 471 |
| Two nodules | 44 |
| Three nodules | 4 |
| Number of nodules | 571 |
| Size of nodules (cm) | 0.92 ± 0.50 |
| Depth of nodules (cm) | 1.38 ± 0.96 |
| Location of nodules | |
| Right upper lobe | 218 |
| Right middle lobe | 48 |
| Right lower lobe | 99 |
| Left upper lobe | 124 |
| Left lower lobe | 82 |
| Type of nodule | |
| Pure GGN | 378 |
| Mixed GGN | 78 |
| Solid nodules | 115 |
The results of microcoil localization
All 571 nodules were marked with microcoils. Due to the unsatisfactory position of the first microcoil, two microcoils were used in 26 nodules. All microcoils distal ends were less than 1 cm away from the nodule. The proximal ends of 476 microcoils were in the chest wall (Figures 1c and 2b). The proximal ends of 95 microcoils were in the pleural cavity (Figure 3b). A number of microcoils in group A, B, and C were 67, 448, and 56, respectively.
The time required for microcoil implantation was 12.9 ± 5.1 min. Post-marking CT showed small pneumothorax in 97 cases (18.7%), mild hemorrhage around the lesion or along the needle track in 139 cases (26.8%) (Figure 2b), and hemoptysis in 8 cases (1.5%). No special treatment was required for any of the complications.
Intraoperative situations of VAST
The time interval between localization and VATS was less than 8 h in 171 cases (187 microcoils), 8–24 h in 269 cases (298 microcoils) and more than 24 h in 79 cases (86 microcoils). 529 nodules were accurately wedge removed under the guidance of the implanted microcoils (Figure 1d). VATS showed dislocation of 42 microcoils, of which 30 were type II (Figure 2c) and 12 were type I (Figure 3c). The bleeding points of the pleural puncture were found in 24 cases with microcoil dislocation (Figure 3c). Combined with the position relationship between the pleural puncture point and the lesion on post-marking CT, the lesion was successfully wedge resected. Palpation found nodules or the intrapulmonary portion of the microcoils in eight cases, and wedge resection were completed successfully. According to preoperative CT, considering the possibility of infiltrating adenocarcinoma, direct lobectomy was performed in five cases with microcoil dislocation. Five cases were converted to thoracotomy.
Pathological diagnosis of nodules
All PNs were pathologically diagnosed after VATS, where 78.1% (446/571) were malignant. The pathological diagnosis results of the nodules were shown in Table 2.
Table 2.
Postoperative pathological results of 571 PNs
| Number | Percentage | |
|---|---|---|
| Malignant nodules | 446 | 78.1% |
| Infiltrating adenocarcinoma | 211 | 37.0% |
| minimally invasive adenocarcinoma | 171 | 29.9% |
| Carcinoma in situ | 46 | 8.1% |
| Mucinous adenocarcinoma | 8 | 1.4% |
| Squamous cell carcinoma | 5 | 0.9% |
| Metastasis | 3 | 0.5% |
| Carcinoid | 1 | 0.20% |
| Scar cancer | 1 | 0.20% |
| Benign nodules | 125 | 21.9% |
| Inflammation | 32 | 5.6% |
| Atypical adenomatous hyperplasia | 27 | 4.7% |
| Fibrosis | 19 | 3.3% |
| Reactive lymph node | 17 | 3.0% |
| Granuloma Adenoma |
11 8 |
1.9% 1.4% |
| Cryptococcus infection | 4 | 0.7% |
| Hamartoma | 4 | 0.7% |
| Carbon power deposit | 3 | 0.5% |
The dislocation rate of each group and statistical comparison
There was no significant difference in general conditions of patients and nodules between the pleural cavity group and the chest wall group. The rates of microcoil dislocation in the pleural cavity group and the chest wall group were 6.3% (6/95) and 7.6% (36/476), respectively. The difference was not significant (x2 = 0.18, p = 0.433).
There was no significant difference in age, gender, lesion size, depth, location, the time interval between microcoil localization, and VATS among groups A, B, and C. The rates of microcoil dislocation in group A, B, and C were 11.9% (8/67), 5.8% (26/448), and 14.3% (8/56), respectively. The difference was statistically significant (x2 = 7.598, p = 0.008).
Table 3 showed the distribution and proportion of two types of microcoil dislocation in each group. Type I was more common in the pleural cavity group than in the chest wall group. There was a significant correlation between the length of microcoil outside the pleura and the type of microcoil dislocation. In group A, 75% of dislocations were Type I, while in group C, all eight dislocations were Type II.
Table 3.
The distribution and proportion of two types of microcoil dislocation in each group
| Complete retraction into the lung | Complete withdrawal from the lung | |||
|---|---|---|---|---|
| Number | Proportion | Number | Proportion | |
| The pleural cavity group | 5 | 83.3% | 1 | 16.7% |
| The chest wall group | 7 | 19.4% | 29 | 80.6% |
| Group A | 6 | 75% | 2 | 25% |
| Group B | 6 | 23.1% | 20 | 76.9% |
| Group C | 0 | 0% | 8 | 100% |
The interval between microcoil localization and VATS had no significant effect on the rates of microcoil dislocation. For interval between localization and VATS less than 8 h, 8–24 h and more than 24 h, the rate of microcoil dislocation were 6.4% (12/187), 8.1% (24/298), and 6.9% (6/86), respectively (x2 = 0.47, p = 0.79). The rates of microcoil dislocation for pure GGNS, mixed GGNS, and solid nodules were 7.9% (30/378), 6.4% (5/78), and 6.1% (7/115), respectively (x2 = 0.54, p = 0.77).
Discussion
Small PNs, especially GGNs, are often invisible and impalpable during VATS.5,6 Preoperative CT-guided localization has been widely used, which can effectively guide VATS wedge resection of small peripheral PNs.6–18 Microcoil and hook-wire are the most commonly used materials for preoperative localization of PNs.6,14–28 Compared with localization using hook-wire, microcoil localization requires measuring the distance from the introducer needle tip to the visceral pleura, deploying the microcoil with the proximal end beyond the visceral pleura, keeping a proper proportion of the intrapulmonary portion and the extrapulmonary portion of the microcoil. So, deploying a microcoil is more complex than releasing a hook-wire. Previous study showed that CT-guided microcoil localization took longer time than hook-wire localization.29 On the other hand, microcoil is soft and pliable, causing little damage to the pulmonary parenchyma after implantation into the lungs or even after falling off. It does not cause any additional injury with physiological respiratory motion. Moreover, the rayon covered on the surface can play a role in filling the needle passage to stop bleeding. In comparison, hook-wire is stiff. After localization with a hook-wire, the patient’s position should be maintained. There is a limitation in patients who cannot maintain a specific position, such as the prone or lateral decubitus position. Therefore, the interval time between hook-wire localization and VATS should be as short as possible. Previous four studies that directly compared microcoil localization and hook-wire localization had shown that patients with microcoil localization had less pain and fewer complications than those with hook-wire localization.28–31 Meanwhile, the dislocation rate of microcoil localization (0–5.1%) was lower than that of hook-wire localization (4.7%–46.2%), and the success rate of microcoil localization (94.9%–100%) was higher than that of hook-wire localization (53.8%–95.3%).28–31
The method of microcoil localization is divided into two kinds: one is to place the entire microcoil adjacent to or within the nodule without pleural marking21 ; the other is to place the microcoil distal end adjacent to or within the nodule, while the microcoil proximal end outside the visceral pleura.19 For the former method, the operation of microcoil localization is simple and requires shorter time, but intraoperative fluoroscopy is needed to determine the location of the implanted microcoil during VATS.21 Intraoperative fluoroscopy not only requires using a mobile fluoroscopy system or a hybrid operating room but also is time-consuming, costly, and increases radiation exposure of both the patients and the surgeons. The operation of microcoil localization is more complicated in the latter method. On the other hand, the microcoil proximal end is exposed outside the pleura and can be seen by naked eyes, surgeon can accurately judge the location of the microcoil without the aid of intraoperative fluoroscopy.22,23 According to the relation between the lesion and the microcoil on the post-marking CT, PNs can be accurately resected under the guidance of the implanted microcoils. In this study, we used the latter method described by Mayo19 but made some adjustments to microcoil position. Mayo et al19 advocated that the microcoil proximal end coiled in the pleural cavity. It is challenging to accurately place the microcoil proximal end in the pleural cavity instead of the chest wall in the absence of a small pneumothorax. In this study, the microcoil distal end was placed less than 1 cm away from the nodule (within or beyond the nodule), and the microcoil proximal end outside the visceral pleura (in the pleural cavity or chest wall). Statistical results showed that placing microcoil proximal end in the pleural cavity and placing it in the chest wall had similar microcoil dislocation rates (6.3% vs 7.6%). Compared with the microcoil localization method described by Mayo, our management of microcoil position significantly reduced the technical difficulty of microcoil localization. Under the premise of ensuring the localization effect, reducing the technical difficulty can shorten the marking time, reduce the patient’s discomfort and radiation exposure, and make it easier for the technology to be widely applied.
Microcoil dislocation is the main cause of localization failure. When the microcoil proximal end is in the chest wall and the distal end is in the lung parenchyma, the following aspects may be related to microcoil dislocation. Firstly, movement such as breathing may lead to microcoil dislocation. The chest wall portion of the microcoil does not move, while the intrapulmonary portion moves up and down with the breath. The nonsynchronous movement of the two parts of the microcoil will lead to mutual traction. Secondly, the implanted microcoil changes its original shape. The elastic restoration may be the cause of microcoil dislocation. Thirdly, involved lung collapse may be the main cause of microcoil dislocation. The microcoil dislocation may mostly occurs during one-lung ventilation with involved lung collapse. When the microcoil proximal end is in the pleural cavity and the distal end is in the lung parenchyma, the elastic restoration may be the main cause of microcoil dislocation.
Microcoil dislocation included two types: complete retraction into the lung (type I) and complete withdrawal from the lung (type II). When the microcoil is fully retracted into the lung, the pleural marking function is lost, but the distal marking nodule function still exists. With the aid of intraoperative fluoroscopy, the position of the microcoil can be accurately identified. Wedge resection of the lesion can be performed according to the relationship between the microcoil and the lesion. So with the help of intraoperative fluoroscopy, type I dislocation does not affect the success rate of VATS resection. However when type II dislocation occur, the roles of marking pleura and nodule are lost at the same time, which may affect the success rate of VATS resection.
This study showed that the rate of microcoil dislocation was similar in the pleural cavity group and the chest wall group, but the type of dislocation in the two groups were obviously different. 83.3% (5/6) of microcoil dislocation were type I in the pleural cavity group, while 80.6% (29/36) of microcoil dislocation were type II in the wall group. This study also showed that the rate and type of microcoil dislocation were significantly correlated with the length of microcoil outside the pleura. So, it was very important to ensure that the microcoil was properly proportional between the intrapulmonary portion and the extrapulmonary portion. When the length of microcoil outside the pleura was less than 0.5 cm or more than 2 cm, the rate of microcoil dislocation was relatively high. In this study, all patients had no obvious discomfort after microcoil localization, and 348 (67.1%) patients underwent VATS resection of PNs more than 8 h after microcoil localization. The result showed that microcoil localization and VAST were scheduled on the different day was safe and did not increased the rate of microcoil dislocation.
There are limitations in this study. Firstly, the study was a single-center retrospective study. Sampling error was inevitable. Due to the large sample size of this study, the corresponding error could be overcome to a certain extent. Secondly, the influence of the size, depth, location of PNs on microcoil dislocation was not analyzed. Thirdly, only one type of microcoil (Cook Tornado) was used in this study. It was 7 cm long when straightened, and was pushable and fibred microcoils. It may have more potential advantages to mark lesions with different depths using microcoils of different lengths and/or shapes.
In conclusion, during CT-guided microcoil localization of PNs, the length of microcoil outside the pleura was significantly correlated with the rate and type of microcoil dislocation. Placing the microcoil proximal in the pleura cavity or chest wall had no significant effect on the rate of microcoil dislocation. Microcoil localization and VATS were scheduled on the different day was safe and did not increased the rate of microcoil dislocation.
Contributor Information
Zhen-Guo Huang, Email: zhuang680911@163.com.
Cun-li Wang, Email: zhuanlongzhang@126.com.
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