ObjectiveTo explore the application value of CT-guided microcoil localization in pulmonary nodule (diameter≤15 mm) surgery.MethodsThe clinical data of 175 patients with pulmonary nodules who underwent single utility port video-assisted thoracoscopic surgery at Nanjing Drum Tower Hospital from August 2018 to December 2019 were retrospectively analyzed. According to whether CT-guided coil localization was performed before operation, they were divided into a locating group and a non-locating group. There were 84 patients (34 males, 50 females, aged 57.8±8.8 years) in the locating group and 91 patients (46 males, 45 females, aged 57.6±10.8 years) in the non-locating group. The localization success rate, localization time, incidence of complications, surgical and postoperative conditions were analyzed between the two groups.ResultsAll 84 patients in the locating group were successfully located, and localization time was 19.0±3.6 minutes. Among them, 19 (22.6%) patients had a small pneumothorax, 4 (4.8%) pulmonary hemorrhage and 2 (2.4%) coil shift; 6 (7.1%) patients had mild pain, 3 (3.6%) moderate pain and 1 (1.2%) severe pain. Sex (P=0.181), age (P=0.673), nodule location (P=0.167), nature of lesion (P=0.244), rate of conversion to thoracotomy (P=0.414), rate of disposable resection of nodules (P=0.251) and postoperative hospital stay (P=0.207) were similar between the two groups. There were significant differences in nodule size (P<0.001), nature of nodule (P<0.001), the shortest distance from nodule to pleura (P<0.001), operation time (P<0.001), lung volume by wedge resection (P=0.031), number of staplers (P<0.001) and total hospitalization costs (P<0.001) between the two groups.ConclusionCT-guided microcoil localization has the characteristics of high success rate, and is simple, practicable, effective, safe and minimally invasive. Preoperative CT-guided microcoil localization has important clinical application value for small pulmonary nodules, especially those with small size, deep location and less solid components. It can effectively shorten the operation time, reduce surgical trauma and lower hospitalization costs, which is a preoperative localization technique worthy of popularization.
For rat spinal magnetic resonance imaging (MRI) experiments, due to the lower main magnetic field strength, shallower detected depth and poor spatial compatibility of the traditional radio frequency (RF) coil, the image signal-to-noise ratio (SNR) of rat spinal was rather lower. In this paper, a RF coil for rat spinal MRI at 9.4 T was developed to improve the image quality and at the same time to avoid the space limitation while scanning in special conditions (cardiac catheterization, etc.). In this article, open birdcage structure was built and magnetic field distribution was calculated. The phantom and rat spine MRI imaging were experimented at 9.4 T to verify the advantage of the coil in rat spine MRI application.
Currently, transcranial magnetic stimulation (TMS) has been widely used in the treatment of depression, Parkinson’s disease and other neurological diseases. To be able to monitor the brain’s internal activity during TMS in real time and achieve better treatment outcomes, the researchers proposed combining TMS with neuroimaging methods such as magnetic resonance imaging (MRI), both of which use Tesla-level magnetic fields. However, the combination of strong current, large magnetic field and small size is likely to bring physical concerns which can lead to mechanical and thermal instability. In this paper, the MRI static magnetic field, the TMS coil and human head model were built according to the actual situations. Through the coupling of the magnetic field and the heat transfer module in the finite element simulation software COMSOL, the force and temperature of the TMS coil and head were obtained when the TMS was used in combination with MRI (TMS-MRI technology). The results showed that in a 3 T MRI environment, the maximum force density on the coil could reach 2.51 × 109 N/m3. Both the direction of the external magnetic field and the current direction in the coil affected the force distributions. The closer to the boundary of the external magnetic field, the greater the force. The magnetic field generated by the coil during TMS treatment increased the temperature of the brain tissue by about 0.16 °C, and the presence of the MRI static magnetic field did not cause additional thermal effects. The results of this paper can provide a reference for the development of the use guidelines and safety guidelines of TMS-MRI technology.
The gradient field, one of the core magnetic fields in magnetic resonance imaging (MRI) systems, is generated by gradient coils and plays a critical role in spatial encoding and the generation of echo signals. The uniformity or linearity of the gradient field directly impacts the quality and distortion level of MRI images. However, traditional point measurement methods lack accuracy in assessing the linearity of gradient fields, making it difficult to provide effective parameters for image distortion correction. This paper introduced a spherical measurement-based method that involved measuring the magnetic field distribution on a sphere, followed by detailed magnetic field calculations and linearity analysis. This study, applied to assess the nonlinearity of asymmetric head gradient coils, demonstrated more comprehensive and precise results compared to point measurement methods. This advancement not only strengthens the scientific basis for the design of gradient coils but also provides more reliable parameters and methods for the accurate correction of MRI image distortions.
ObjectiveTo compare the effectiveness and safety of preoperative lung localization by microcoil and anchor with scaled suture.MethodsA total of 286 patients underwent CT-guided puncture localization consecutively between October 2019 and December 2020 in our hospital. According to the different methods of localization, they were divided into a microcoil group (n=139, including 49 males and 90 females, aged 57.92±10.51 years) and an anchor group (n=147, including 53 males and 94 females, aged 56.68±11.31 years). The clinical data of the patients were compared.ResultsA total of 173 nodules were localized in the microcoil group, and 169 nodules in the anchor group. The localization success rate was similar in the two groups. However, the anchor group was significantly better than the microcoil group in the localization time (8.15±2.55 min vs. 9.53±3.08 min, P=0.001), the pathological receiving time (30.46±14.41 min vs. 34.96±19.75 min, P=0.029), and the hemoptysis rate (10.7% vs. 30.1%, P=0.001), but the pneumothorax rate was higher in the anchor group (21.3% vs. 11.0%, P=0.006).ConclusionPreoperative localization of small pulmonary nodules using anchor with suture is practical and safe. Due to its simplicity and convenience, it is worth of promotion in the clinic.
The therapeutic effects of transcranial magnetic stimulation (TMS) are closely related to the structure of the stimulation coil. Based on this, this study designed an A-word coil and proposed a multi-strategy fusion multi-objective slime mould algorithm (MSSMA) aimed at optimizing the stimulation depth, focality, and intensity of the coil. MSSMA significantly improved the convergence and distribution of the algorithm by integrating a dual-elite guiding mechanism, a hyperbolic tangent control strategy, and a hybrid polynomial mutation strategy. Furthermore, compared with other stimulation coils, the novel coil optimized by the MSSMA demonstrates superior performance in terms of stimulation depth. To verify the optimization effects, a magnetic field measurement system was established, and a comparison of the measurement data with simulation data confirmed that the proposed algorithm could effectively optimize coil performance. In summary, this study provides a new approach for deep TMS, and the proposed algorithm holds significant reference value for multi-objective engineering optimization problems.
Objective To investigate the technical feasibility and effectiveness of intraoperative sac embolizaion with coils and fibrin glue for preventing type Ⅱ endoleak after endovascular aneurysm repair (EVAR). Methods A patient with abdominal aortic aneurysm (AAA), which had high risk of type Ⅱ endoleaks, was treated with combined packing of coils and fibrin glue in order to prevent type Ⅱ endoleak after EVAR. Percutaneous catheter preset and balloon occlusion were used to ensure accurate packing. Results At the end of the operation, the angiography showed that the blood flow of the stent and distal artery was unobstructed, there was no type Ⅰ and Ⅲ endoleaks, and delayed angiogram showed no collateral circulation of aneurysm. The procedure was successful. The operative duration was 120 min and the blood loss was only 20 mL. No complications such as colonic ischemia and ectopic embolism occurred, and the patient was discharged on 3 days after operation. At 6 months after follow-up, the computerized topographic angiography showed that the aneurysm cavity was completely thrombotic, without type II endoleak, and the diameter and volume of aneurysm were reduced. Conclusions The technique of intraoperative sac embolizaion with coils and fibrin glue during EVAR is safe and effective to prevent postoperative endoleaks, which is simple and feasibility. Intraoperative indwelling catheter and balloon blocking are the key points of successful implementation of this technique.
ObjectiveTo identify risk factors for severe elastic recoil after percutaneous transluminal angioplasty (PTA) in the femoropopliteal artery disease based on intravascular ultrasound (IVUS) imaging and to develop a risk prediction model. MethodsA retrospective analysis was conducted on the clinical data from the patients with femoropopliteal artery disease treated at the First Affiliated Hospital of Chongqing Medical University from September 2020 to February 2022. Based on the IVUS images, a multivariate logistic regression analysis was conducted to identify the risk factors for severe elastic recoil in the patients with femoropopliteal artery disease after PTA. A nomogram prediction model was established to predict the occurrence of severe elastic recoil, and the area under receiver operating characteristic curve (AUC) was used to evaluate its ability to distinguish the occurrence of severe elastic recoil, which was validated using a calibration curve. ResultsA total of 34 patients with femoropopliteal artery disease who received PTA treatment were enrolled. Of the 803 vessel slices were analyzed, 451 (56.16%) demonstrated severe elastic recoil on IVUS imaging. The multivariate logistic regression analysis showed that the increased plaque burden, luminal eccentric index, external elastic membrane remodeling index, and the external elastic membrane-balloon area ratio were the risk factors for the occurrence of severe elastic recoil (P＜0.05). The AUC of the nomogram prediction model based on these risk factors exhibited moderate discrimination [AUC (95%CI)=0.775 (0.732, 0.818)]. The predicted probability of the nomogram model for severe elastic recoil was in a good agreement with the actual probability (P=0.862). ConclusionThe severe elastic recoil prediction model developed in this study, based on IVUS imaging data, can effectively identify high-risk factors for severe elastic recoil after PTA in patients with femoropopliteal artery disease, demonstrating a moderate predictive discrimination capability.
Magnetic induction method aims at the noninvasive detection of liver iron overload by measuring the hepatic magnetic susceptibility. To solve the difficulty that eddy current effects interfere with the measurement of magnetic susceptibility, we proposed an improved coil system based on the static field magnetization principle in this study. We used a direct current excitation to eliminate the eddy current effect, and a rotary receiver coil to get the induced voltage. The magnetic field for a cylindrical object due to the magnetization effect was calculated and the relative change of maximum induced voltage was derived. The correlation between magnetic susceptibility of object and maximum magnetic flux, maximum induced voltage and relative change of maximum induced voltage of the receiver coil were obtained by simulation experiments, and the results were compared with those of the theory calculation. The contrast shows that the simulation results fit the theory results well, which proves our method can eliminate the eddy current effect effectively.
ObjectiveTo systematically evaluate the application effect of CT-guided Hook-wire localization and CT-guided microcoil localization in pulmonary nodules surgery. MethodsThe literatures on the comparison between CT-guided Hook-wire localization and CT-guided microcoil localization for pulmonary nodules were searched in PubMed, EMbase, The Cochrane Library, Web of Science, Wanfang, VIP and CNKI databases from the inception to October 2021. Review Manager (version 5.4) software was used for meta-analysis. The Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of studies.ResultsA total of 10 retrospective cohort studies were included, with 1 117 patients including 473 patients in the CT-guided Hook-wire localization group and 644 patients in the CT-guided microcoil localization group. The quality of the studies was high with NOS scores>6 points. The result of meta-analysis showed that the difference in the localization operation time (MD=0.14, 95%CI −3.43 to 3.71, P=0.940) between the two groups was not statistically significant. However, the localization success rate of the Hook-wire group was superior to the microcoil group (OR=0.35, 95%CI 0.17 to 0.72, P=0.005). In addition, in comparison with Hook-wire localization, the microcoil localization could reduce the dislocation rate (OR=4.33, 95%CI 2.07 to 9.08, P<0.001), the incidence of pneumothorax (OR=1.62, 95%CI 1.12 to 2.33, P=0.010) and pulmonary hemorrhage (OR=1.64, 95%CI 1.07 to 2.51, P=0.020). ConclusionAlthough Hook-wire localization is slightly better than microcoil localization in the aspect of the success rate of pulmonary nodule localization, microcoil localization has an obvious advantage compared with Hook-wire localization in terms of controlling the incidence of dislocation, pneumothorax and pulmonary hemorrhage. Therefore, from a comprehensive perspective, this study believes that CT-guided microcoil localization is a preoperative localization method worthy of further promotion.