Optimal multimodal virtual bronchoscopy for convex-probe endobronchial ultrasound

Abstract

Accurate staging of the central-chest lymph nodes is a major step in the management of lung-cancer patients. For this purpose, the physician uses videobronchoscopy to navigate through the airways and convex-probe endobronchial ultrasound (CP-EBUS) to localize extraluminal lymph nodes. Unfortunately, CP-EBUS proves to be difficult for many physicians. In this paper, we present a complete optimal multimodal planning and guidance system for image-guided CP-EBUS bronchoscopy. The system accepts a patient's 3D chest CT scan and an optional whole-body PET/CT study as inputs. System work flow proceeds in two stages: 1) optimal procedure planning and 2) multimodal image-guided bronchoscopy. Optimal procedure planning entails CT-based computation of guidance routes that enable maximal feasible tissue sampling (depth-of-sample) of selected lymph nodes. Multimodal image-guided bronchoscopy next occurs in the operating room. The guidance process draws upon a CT-based virtual multimodal bronchoscope that gives virtual views of videobronchoscopy and CP-EBUS, similar to those provided by a real linear integrated CP-EBUS bronchoscope. The system provides CT/PET-based graphical views along the guidance route toward a lymph node, per the two-stage process of videobronchoscopic navigation and CP-EBUS localization. The guidance views depict the depth-of-sample information dynamically to enable visualization of optimal tissue-biopsy sites. The localization process features a novel registration be- tween the virtual CP-EBUS views and live CP-EBUS views to enable synchronization. A lung-cancer patient pilot study demonstrated the feasibility, safety, and efficacy of the system. Procedure planning effectively derived optimal tissue-biopsy sites and also indicated sites where biopsy may not be safe, within preset constraints. During live bronchoscopy, we performed successful guidance to all selected lymph nodes.