416	D. Khemasuwan and A. C. Mehta

visible portions of the airways. The next step in guiding the bronchoscopic biopsy tools through the lung periphery has been electromagnetic navigation (EMN). Real-time guidance and the ability to steer biopsy instruments to the pre-selected virtual peripheral lesion is critical for a successful bronchoscopic biopsy procedure. EMN is a novel technology that facilitates approaching peripheral lung lesions which are dif cult to biopsy with conventional TBBx. In this review, we describe existing electromagnetic navigation technologies with particular focus on available clinical data, procedural maneuver, and limitations. To date, there are two major platforms for EMN are available in the US; (1) superDimension Navigation System (Medtronic, Minneapolis, MN) and (2) SPiN System (Veran Medical Technologies, Inc., St. Louis, MO).

What Is Electromagnetic Navigation?

The navigation system involves creating an electromagnetic (EM) eld around the patient’s chest and then directing bronchoscopic biopsy tools using a micro-sensor placed upon previously acquired CT images. In other words, EMN is an image-guided localization device which assists in placing bronchoscopic biopsy tools in the targeted areas of the lung. The principles, the components, and procedural maneuvers of the EMN are provided below [8–13].

SuperDimension Navigation System (EMN-SD)

EMN-SD operates on the principles of electromagnetism. Electromagnetic Location Board emits low frequency electromagnetic (EM) waves. The patient is in supine position and their torso is placed within the electromagnetic eld created by the board (Fig. 24.1).

A retractable micro-sensor probe is mounted on the tip of a fexible cable Locatable Guide (LG) (Fig. 24.2). This micro-sensor is the cardinal feature of the system. Once placed within the EM eld, its position in x, y, z axes as well as in-­ motion (rotate, forward and backward) is captured by the EMN system and displayed on the

Fig. 24.1  Electromagnetic location board placed at the cephalic end of the bronchoscopy table

monitor in real-time. These images are superimposed upon previously acquired CT images (Fig. 24.3).

Computerized Tomography

To overlay the patient’s radiographic information on the patient’s anatomy in the electromagneticeld, a high-resolution spiral CT scan of the chest is performed (with or without the contrast) and reconstructed with a protocol speci c to the scanner manufacturer. The recommended reconstruction protocols optimize CT images suitable for planning and navigation with slice thickness between 1.0 and 1.25 mm; a slice interval range between 0.8 and 1.0 mm; and image overlap between 20 and 50% [14]. DICOM (Digital Imaging Communication in Medicine) images from a low dose CT scan can be accepted and viewed in the planning module; however, the detail and quality of the images produced may not be suitable to enable the advanced features of the EMN system. The information is gathered in the DICOM format and placed either on a compact disc or directly down-loaded on the system’s laptop from the picture archiving and communication system (PACS).

Computer Interphase

The SuperDimension system provides dedicated software for “Planning” and “Navigation procedure.” The CT chest images can be transferred from PACS into DICOM CD and the images can be uploaded directly into the planning software.

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24  Electromagnetic Navigation: A Review	417

Fig. 24.2  (Top) The edge navigation catheter with sensor at the distal tip. (Bottom) Edge navigation catheter assembled with a working channel of bronchoscope

Fig. 24.3  (Left) The position of locatable guide (LG) at the main carina in coronal view CT scan and (Right) real-time superimposed bronchoscopic image of LG at the main carina

The planning software program provides images of the chest in coronal, sagittal, and axial fashion as well as a virtual bronchoscopic image and a three-dimensional representation of the patient’s

tracheobronchial tree and pleura. These images are used to plan all aspects of the procedure. The main computer software and the monitor allow the bronchoscopist to view the reconstructed