Cone Beam CT Guided Electromagnetic Navigational Bronchoscopy

Electromagnetic navigation bronchoscopy has been used for more than a decade to access peripheral and central parenchymal lung lesions bronchoscopically. Traditionally standard fluoroscopy using C-arm is used to confirm the location and guide the biopsy instruments under real-time guidance. With availability of Cone Beam CT, fluoroscopic images of much higher quality and resolution can be obtained intra-operatively. It also enables the bronchoscopist to obtain intraoperative CT images and confirm the exact location of the lesion and the Bronchoscopic biopsy catheter or the biopsy instruments.

At my institution, lung nodules/masses requiring ENB have been approached using Medtronic Super-Dimension Version 7 Electromagnetic Navigational Bronchoscopy system. All the procedures are done under fluroscopic guidance using a regular C-Arm. All the lesions are confirmed using peripheral Endobronchial Ultrasound (EBUS). Once the appropriate location is reached, biopsy is obtained using FNA (18G or 21G), Single or Triple needle brush, Transbronchial forceps and Bronchoalveolar lavage.

A pathologist is present on site for all the cases to review the slides and assist in diagnosis. All the cases are done under general anesthesia through endotracheal tube.

Also, all the ENB procedures have been performed by one Interventional Pulmonologist since August 2017.

For the interventional arm, all the aspects will remain the same except that the cases are done in Hybrid OR instead of Endoscopy. All the patients are completely paralyzed intra-operatively. Also, instead of a standard C-Arm providing 2D fluoroscopic guidance, a Philips Azurion 7 C20 FlexMove system with Emboguide, 3D Segmentaion and Overlay tools is being used. This enables the bronchoscopist to obtain a CT scan of the chest and also segment out the lesion(s) of interest and to overlap the 3-D image of the lesion on live fluoroscopy in all 3 dimensions.

During the ENB procedures, at least 1 full Xpert CT is going to be obtained, mostly after completing the airway registration and ENB guided approach the lesion. Once the extended working channel and the locatable guide is advanced to the lesion using ENB guidance, the catheter is locked and scope held in place. The patient is maintained in inspiratory breath hold and Cone Beam Ct is used to obtain the Xpert CT that shows the lesion and surrounding lungs, chest and mediastinal structures in the surrounding area of the chest.

This is then used to analyze the location of the lesion and the lesion of the extended working channel, locatable guide and the biopsy instruments in relation to the lesion. The lesion is then segmented and EmboGuide+Overlay feature is used to project a 3D view of the lesion on the live fluoroscopic images in all three axis. This also allows the bronchoscopist to obtain Anterior-posterior, Lateral and oblique views at various angles while maintaining the 3D overlap.

Additional CT scans might be obtained intra-operatively if needed to guide the biopsy catheter appropriately towards the lesion. Due to the live nature of the Cone Beam CT, it is much more capable of providing accurate guidance regarding the location of the lesion and the biopsy instruments. hence, in case of any discrepancy, information provided by Cone Beam CT is considered more reliable and used with higher confidence.

Rest of the steps involved in procedure are similar between the control and the interventional arm including the surgeon, type of bronchoscopes, type of electromagnetic navigational system, use of peripheral Endobronchial Ultrasound and availability of on-site pathologist. The biopsy instruments used are also the same including transbronchial needle for FNA, Single or triple needle brush and transbronchial forceps. Bronchoalveolar lavage is also obtained at the end via extended working channel.

All the patients undergoing biopsy of the peripheral/central lung lesions using ENB also undergo Convex EBUS guided mediastinal surveillance and EBUS-TBFNA of any Lymph Node that appears to be greater than 5 mm on EBUS exam.

My study aims to study the effect of using Cone Beam CT with segmentation, 3-D overlay and CT augmented fluoroscopy on sensitivity and diagnostic yield of electromagnetic navigation bronchoscopy for diagnosis of peripheral and central lung lesions including lung nodules and masses which could not be directly accessed using just white light bronchoscope.