In recent years, the incidence of lung cancer has been second only to breast cancer; however, it still has the highest mortality rate8. With the increasing popularity of low-dose spiral CT in physical examination, the detection rate of small pulmonary nodules has increased significantly. Approximately 50% of small pulmonary nodules are malignant9. However, it is difficult to identify the pathology using traditional CT-guided percutaneous lung puncture and bronchoscopy with biopsy, and false-negative results occur. According to relevant reports10,11, in 29% of cases, the possibility of malignancy cannot be ruled out due to insufficient histological evidence. Video-assisted thoracoscopic surgery (VATS) has the advantages of a high diagnostic rate, short operation time, and minimal trauma; thus, it has become an important method for the diagnosis and treatment of small pulmonary nodules11. However, VATS has limitations in terms of resection of small pulmonary nodules due to the small size of the pulmonary nodules and difficulty with lesion localization. As a result, accurate positioning has become the key to the diagnosis and treatment of small pulmonary nodules. Multiple positioning methods used in the clinical setting can be broadly divided into two categories: intraoperative non-invasive localization and preoperative invasive localization. Among them, the common non-invasive localization methods include intraoperative finger palpation and intraoperative ultrasound localization.
Invasive localization methods include CT-guided hook-wire localization, CT-guided percutaneous injection of material (micro-coil positioning, methylene blue, agar positioning, barium, lipiodol, medical glue, etc.) for positioning and other positioning methods. In recent years, relevant medical practitioners have used electromagnetic navigation bronchoscopy (ENB) for intraoperative positioning. Awais and Luo et al12,13 confirmed the successful application of ENB in the localization and resection of pulmonary nodules, the diagnostic rate of which was similar to those of other preoperative invasive localization methods such as percutaneous lung puncture localization; the rates of complications such as pneumothorax and bleeding were also significantly reduced14. However, only a few hospitals in China own the required equipment, and the demanding operational technique of ENB and the relatively high cost of the equipment has limited its clinical popularization.
It is generally believed that the CT-guided hook-wire localization technique is the most commonly used pulmonary nodule localization technology 5, 6, 15. This localization technique requires the placement of an anchor needle (first used in the localization of breast lumps) in the lung tissue adjacent to the pulmonary nodule under CT guidance. This locating needle is a disposable pulmonary nodule locating needle improved by Fan16 et al. based on the traditional hook-wire positioning device. The most common complication of this positioning technique is pneumothorax. Hanauer17 et al. studied 181 cases of solitary pulmonary nodules and found that the rate of pneumothorax in patients underwent hook-wire localization could reach 38%. The incidence of pneumothorax in this study was 16% (8/50), which was lower than that reported in the above study. This may be related to the skilled operation of the surgeons and their mastery of the indications for preoperative hook-wire puncture positioning. Upon studying 276 patients with hook-wire positioning, Iguchi et al.18 concluded that increased respiratory motion during positioning, pulmonary nodules that are located in the lower lobe of the lung, pulmonary nodules with solid components, prone patient position, and puncture path that passes through the interlobar fissures are all factors that may cause pneumothorax.
Most patients have mild symptoms that do not require special treatment. Li et al.19 reported that the incidence of hook-wire pulmonary hemorrhage was 13.9–36%. In this study, the incidence of intrapulmonary hemorrhage was 4% (2/50), which is much lower than those reported in the above-mentioned studies. This may be related to the small number of cases in the localization group. Hwang et al.20 performed hook-wire localization in 45 patients and found that hook-wire displacement occurred in 8.9% of patients. In our study, half-shedding occurred only in one patient (2%) after positioning. The displacement rate was much lower than that reported in the other hook-wire studies. In the one case in which the locating needle fell off in this study, the lesion was relatively close to the pleura. The displacement of the locating needle is related to the depth of the release position of the puncture needle and preoperative pulling to the locating needle. Pleural reactions are generally caused by irritation of the pleura by detachment of the positioning line or the locating needle, which is common in elderly and frail patients. In this patient, the occurrence of pleural reaction was due to his excessive tension and weakness, leading to dizziness and a decrease in blood pressure after the puncture; his symptoms were relieved after rest, and no serious complications occurred. However, in clinical practice, it is necessary to prevent the occurrence of severe pleural reactions.
In the diagnosis and treatment of small pulmonary nodules, CT-guided hook-wire localization technology can reportedly21 help accurately locate and rapidly remove lesions during thoracoscopic surgery, thus effectively shortening the operation time.The duration of thoracoscopic surgery, intraoperative bleeding and hospital stay of patients in both groups were recorded, and the results showed that the operation time, intraoperative bleeding and hospital stay in the positioning group were significantly lower than those in the control group, which is consistent with the results of the above studies.
This study explored the efficacy and safety of CT-guided hook-wire localization in thoracoscopic surgery for small pulmonary nodules through clinical practice with a certain number of cases. The univariate analysis revealed that three variables were associated with localization-related pneumothorax. The number of localized small pulmonary nodules was an independent risk factor for localization-related pneumothorax, as was indicated by multivariate regression analysis, consistent with previous findings22. Considering that relatively more holes were created by the insertion of multiple locating needles into the visceral pleura due to the simultaneous placement of two locating needles in our study, the chance of air entering the pleural cavity was increased23. In the course of clinical diagnosis and treatment, many patients have multiple occurrences of pulmonary nodules. The incidence of pneumothorax in patients during localization process may be relatively high, so effective measures to prevent pneumothorax should be prepared before the procedure. The rate of conversion to thoracotomy in the two groups was 2% versus 16% (control versus localization group), and the difference was statistically significant. In this study, 68.9% and 76.3% of the resected small pulmonary nodules in the localization group and the control group, respectively, were finally diagnosed as malignant; both were higher than the previously reported malignancy rate of small pulmonary nodules with a diameter of < 10 mm (6–28%); this may be due to the fact that only those small pulmonary nodules that are highly suspected as malignant by the observation of their imaging properties are further inspected surgically for diagnosis and treatment in clinical practice; no further analysis would be performed because the localization was not necessarily related to the postoperative nature of the nodules. Once the hook-wire localization technique guided by CT is practiced in a large number of cases, it can be developed into a localization technique that is mastered by physicians in clinical departments. This can significantly improve the early diagnosis and resection rates of small pulmonary nodules and provide effective help for the detection and treatment of early-stage lung cancer.
This retrospective study was performed at a single center with a small sample size. Thus, future multicenter studies with large sample sizes are needed to validate our findings.
In conclusion, CT-guided hook-wire localization technique has certain clinical application value in thoracoscopic surgery for small pulmonary nodules. It can accurately locate small pulmonary nodules, reduce intraoperative blood loss, shorten operation time and hospitalization days, and reduce the conversion rate to thoracotomy, thereby facilitating the early diagnosis and treatment of lung cancer. Simultaneous localization of multiple nodules can easily lead to the occurrence of localization-related pneumothorax. Thus, this technique is worth spreading.