Method for Reducing CT-to-Body Divergence Tailored to Peripheral Bronchoscopy

Guided bronchoscopy systems, be they image-guided or robotics-assisted, are revolutionizing the field of bronchoscopy, particularly for tasks in peripheral lung regions. To provide guidance, these systems draw on a procedure plan derived from a patient's 3D chest computed tomography (CT) scan. Generally, a procedure plan gives an airway route leading from the trachea to a distal airway close to a diagnostic region of interest (ROI). Unfortunately, the “virtual” chest space, captured by the CT scan used for planning, differs significantly from the “real” chest space encountered during the live procedure. This so-called CT-to-body divergence (CTBD) can produce large guidance errors during a live bronchoscopy, resulting in procedure failure rates on the order of 30%. CTBD arises because the procedure plan relies on a CT scan depicting the chest near total lung capacity (TLC), while the live procedure occurs with the chest near functional residual capacity (FRC), a much lower lung volume. These differences in lung volume lead to mismatches between the guidance system's perceived 3D chest position and bronchoscope's actual chest position. To address this gap, we propose a two-phase method to help mitigate the impact of CTBD on guided bronchoscopy procedures by utilizing spatial information from CT scans obtained at two different lung states. The first phase entails a dual-space procedure planning method that gives two point-by-point synchronized procedure plans: one in TLC space and the other in FRC space. The second phase involves a dual-space guidance procedure, whereby synchronized information in both TLC and FRC spaces are made available during the guided procedure. Results from TLC/FRC CT scan pairs collected for lung cancer patients verify the potential of the method.