Fig 1.
Schematic operating room setup during navigated EBUS-TBNA.
Preoperative images in DICOM format were imported into the navigation software, and matched to the patient’s position during bronchoscopy (EM-CT-patient registration). When maneuvering the bronchoscope within the electromagnetic tracking (EM) field, the position of the bronchoscope sensor (BS) and EBUS images could be acquired in the navigation system. A reference electromagnetic sensor (RS) was attached on the table.
Fig 2.
Experimental EBUS bronchoscope.
The sensor for electromagnetic tracking was attached close to the convex probe in the tip of the bronchoscope. The connector to the sensor (arrow) was plugged into the control unit of the electromagnetic tracking system.
Fig 3.
Electromagnetic navigated EBUS-TBNA, procedure workflow.
Preoperative preparations included target definition, CT model extraction and image import into the navigation software. During the EBUS procedure, image-to-patient registration was performed using an automatic algorithm in the navigation software. A combination of video, electromagnetic navigated bronchoscopy (ENB) and EBUS was used for target localization and confirmation before EBUS guided fine needle sampling. A variety of options existed for image reconstruction during the procedure or postoperatively.
Fig 4.
Graphical user interface, patient 4.
(A) The CT models of the central airways, a 4R and a 4L lymph node target, the tip of the EBUS-scope and the real-time EBUS image. (B) The corresponding image plane from preoperative CT. The thin white sector represents the exact position of the EBUS image. (C) Regular, real-time EBUS image, showing the 4R lymph node (arrow).
Fig 5.
Navigation system accuracy, patient 3.
(C, D) Orthogonal EBUS planes were projected on top of corresponding planes from the segmented CT models. Here, the axial plane is chosen for method illustration. (B, D) The EBUS and CT position of a 10R lymph node and the superior vena cava after manual shift correction. The resulting position deviation between EBUS and CT was combined for three planes, representing the navigation system accuracy. RMB = Right main bronchus. VCS = Superior vena cava.
Table 1.
Navigated EBUS: Patient baseline data and clinical outcomes.
Table 2.
Navigated EBUS: Technical outcomes.
Fig 6.
Navigated EBUS-TBNA used to assess operability in patient 3.
(A) Preoperative CT indicated a non-curative setting due to a probable lymph node metastasis proximal to the azygos vein (blue). Intraoperative multimodal images correctly placed the lymph node (red) to a different level than CT, concluding with less advanced disease. For improved overview of the vasculature, the airway CT models were not included in this visualization. (C) Real-time EBUS imaging the azygos vein and 10R lymph node (arrow). (B) Corresponding CT plane with US sector position indicated (overlaid the CT).