Robotic bronchoscopy delivery of optical ultrasound imaging for transbronchial lung biopsy guidance

Accurate guidance for transbronchial pulmonary nodule biopsy requires visualisation of targets and tools beyond the airway wall, yet radial endobronchial ultrasound provides only a cross-sectional image orthogonal to the probe axis, and must be withdrawn before a tool is passed, leaving tissue acquisition unguided. Optical ultrasound (OpUS) imaging offers a miniaturised, fibre-based alternative that may enable image guidance from within the narrow distal bronchi. In this study, we evaluated the feasibility of OpUS imaging for endobronchial guidance by deploying a side-viewing, linearly actuated OpUS probe through a clinically available robotic bronchoscopy catheter, and assessed the corresponding imaging performance in separate bench-top experiments within an anatomically correct lung phantom containing airway structures and inclusions. Robotic integration was successful: the 1.8 mm outer-diameter OpUS probe could be delivered through the robotic catheter without visibly impairing catheter navigation, platform operation and probe delivery. The >2 m long probe maintained distal linear actuation through the catheter and tolerated catheter bending down to an estimated bend radius of approximately 5 mm before probe failure. The bench-top experiments confirmed how real-time OpUS imaging (4 Hz) could visualise the inclusion within the lung phantom from inside the airway lumen using a robotic bronchoscopy catheter. In addition, bench-top experiments on image guidance of needle insertions into phantoms confirmed that OpUS imaging is capable of clearly visualising the needle trajectory in settings matching the confined space of endobronchial interventions, supporting the great potential for OpUS image guidance of endobronchial lung biopsies.