ting. There was near-complete ablation (>90%) in 9 of 18 patients. ENB-guided RFA was considered as an alternative method for local tumor control in inoperable candidates with SPN [46]. However, several complications could be encountered­ in 16–35% of patients (pain, hemothorax, pleumothorax, and pleural effusion) [50– 52]. In addition, one limitation of endoscopic RFA is that coagulated necrotic tissue can be formed around the tip. It can lead to inadequate tissue ablation. ENB-guided RFA seems to be a good alternative for treatment of lung cancer in inoperable candidates. In addition to RFA, other therapeutic modalities have been in development for bronchoscopic ablation of peripheral lung tumors which includes photodynamic therapy, and microwave ablation [53–55]. EMN-guided bronchoscopy provides an ability to navigate to the targeted lesions; however, the con rmation remains suboptimal [56]. EMN-guided biopsy and intraprocedural cone-beam CT (CBCT) provide an ability to demonstrate presence of intra-­ lesional bronchoscopic catheters/probes [57]. The clinical data on bronchoscopic ablation for peripheral lung nodules remains to be established. Lastly, the EMN bronchoscopy can also be used to draw a path to locate a distally located foreign body. Such an approach can preclude the need for lobectomy [58].

Complications

Pneumothorax is the most common complication encountered with the use of EMN-guided biopsy and occurs in the range of 0–7.5% [13, 22–34]. In the published studies related to EMN effectiveness in the diagnosis of peripheral lung lesions, 18 patients have developed pneumothorax. Four of these patients needed chest tube drainage while in the remaining 14, it resolved spontaneously. Theoretically the rate of pneumothorax could be affected by AFTRE, as an error of even a few millimeters could be crucial in these small peripheral lesions, especially if the fuoroscopic guidance is not utilized.

Self-limiting bleeding may be encountered in some cases [11, 28]. It is believed that the EWC

also facilitates to tamponade the bleeding by allowing the scope to remain wedged at the subsegmental bronchus throughout the procedure [23, 29].

Limitations

We believe that a major obstacle to the widespread use of the EMN is its cost and the need for expensive disposable LG and EWC. Medical economics can certainly limit its use in developing and third world countries. In addition, there was a concern of using magnetic elds and EMN has been considered relatively contraindicated in patients with pacemakers and implantable cardioverter-­de brillators (ICDs). Khan et al. have shown that the magnetic eld in EMN-­ guided biopsy is less than 0.001 T and the procedure is safe to perform in patients with pacemakers and ICDs [59].

In recent years, several studies have reported a difference between the static pre-procedural CT reconstructions and the dynamic, breathing lung during the bronchoscopic procedure. This term is called “CT-to-body divergence [60].” For EMN-SD, the CT images used in planning the virtual navigation pathway are obtained at full inspiration or inspiration reserve in an awake patient, often several days prior to the procedure. The anatomical difference occurs primarily due to changes in lung volumes in sedated and sometimes mechanically ventilated patients. In addition, intra-­procedural atelectasis can cause inaccurate virtual maps, and cause visual impairment on image modalities. Intraprocedural atelectasis has been well-docu- mented; however, it is often an underappreciated issue [61, 62]. In one study, CBCT identi ed atelectasis in 40% of the cases overall and resulted in a decreased diagnostic yield [63]. Optimizing ventilation protocols with using higher tidal volume (10–12 mL/kg) and positive end expiratory pressure (8–15 cmH2O) may mitigate atelectasis. Furthermore, minimizing unnecessary suctioning, and avoiding over-­ wedging of the airway may signi cantly minimize atelectasis.

Recently, EMN-SD system launched a real-­ time guidance system with Tomosynthesisbased fuoroscopic navigation (Illumisite) which has been available since July 2020. Fluoroscopic navigation uses advanced software algorithms and digital tomosynthesis reconstruction [64, 65] to provide accurate 3D modeling. The retrospective­ study of this new EMN-SD system has showed to improve diagnostic yield compared to standard navigation (79.1% vs. 54.4%) [66].

Summary

Electromagnetic navigation is a novel tool which aids diagnostic yield of fexible bronchoscopy for the peripheral lung lesions. The procedure is safe, effective, and easy and can be performed with or without the use of fuoroscopy. It plays a complementary role with endobronchial ultrasound for mediastinal staging. It has a potential to be an important tool in improving accuracy and outcomes from thoracoscopic resections, external beam radiotherapy, stereotactic body radiation therapy, CyberKnife treatment, and other bronchoscopic ablation techniques. A high initial capital investment and variable costs for disposable LG/biopsy tools could hinder the adoption of this technology in the healthcare system. Furthermore, the diagnostic utility of EMN could suffer from technical challenges, especially CT-to-body divergence. Several imaging techniques provide a real-time con rmation of biopsy tools in the lesions which can be used as an adjunct to EMN-guided biopsy. Novel robotic technologies, such as the Monarch (Auris Health) and ION (Intuitive Surgical) robotic endoscopy platforms, have emerged as the latest wave of navigational bronchoscopy. The Monarch system uses electromagnetic navigation and robotic kinematic data to locate the tip of a bronchoscope in a patient’s airways. Although these two systems are in an early adoptive phase, several publications have supported the systems safely navigating to the peripheral lesion through enhanced dexterity, and stability.

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