Background and Rationale:
Peripheral pulmonary nodules (PPNs) are increasingly detected due to widespread use of computed tomography (CT) imaging and lung cancer screening programs. Current bronchoscopic diagnostic methods, including electromagnetic navigation bronchoscopy (ENB) and radial endobronchial ultrasound (rEBUS), have diagnostic yields of approximately 70%, with lower success rates for smaller nodules (\<20mm), nodules in the outer third of the lung, and those without bronchus sign.
The ION endoluminal system (Intuitive Surgical, Sunnyvale, CA) represents a novel approach using shape-sensing robotic-assisted bronchoscopy (ssRAB) technology. This system employs shape-sensing fiber optics throughout the catheter length to provide real-time catheter position and orientation monitoring, enabling precise navigation and stable positioning capabilities. International studies have reported diagnostic yields of 87-90% with favorable safety profiles.
Study Design and Methodology:
This is a prospective, single-center, observational cohort study designed to evaluate the diagnostic performance and safety of ssRAB in Korean patients. The study will be conducted as part of routine clinical care, with ssRAB replacing conventional bronchoscopy for eligible patients requiring histological diagnosis of peripheral lung nodules.
Pre-procedure Planning:
All participants will undergo thin-section chest CT (≤1.25mm thickness) for 3D navigation planning using PlanPoint Planning Laptop software. Target nodule characteristics, approach pathways, and procedure strategy will be determined prior to the procedure.
Procedure Protocol:
The ssRAB procedure will be performed under deep sedation or general anesthesia using an 8.0mm or larger endotracheal tube. The procedure involves:
1. Initial airway assessment using conventional flexible bronchoscopy
2. ION system docking to the endotracheal tube
3. Vision probe insertion through the ION catheter (3.5mm outer diameter, 2mm working channel)
4. System registration to align navigation mapping with patient anatomy
5. Catheter navigation to target nodule
6. Vision probe removal and radial EBUS confirmation (when applicable)
7. Tissue sampling using various tools (Flexision biopsy needles, forceps, brush, or cryobiopsy)
8. Fluoroscopic guidance when needed
9. Rapid on-site evaluation (ROSE) when available
Safety Monitoring:
All procedure-related complications will be documented according to CTCAE v5.0 criteria. Post-procedure monitoring includes chest imaging to assess for pneumothorax and clinical observation for bleeding, infection, or other adverse events. Participants will be followed for 24 hours post-procedure for immediate complications.
Follow-up and Diagnosis Confirmation:
Participants will be followed for 6 months to establish final diagnosis. For non-specific benign findings, final diagnosis will be confirmed through additional procedures (surgery or CT-guided biopsy) or 6-month follow-up imaging showing nodule improvement or resolution.
Statistical Analysis:
The primary endpoint is diagnostic yield, defined as the proportion of lesions with definitive diagnosis among total sampled lesions. Secondary endpoints include navigation success rate, rEBUS confirmation rate, procedural performance metrics (registration time, navigation time, total procedure time, fluoroscopy time), and safety outcomes. Based on previous studies reporting 87.8% diagnostic yield, a sample size of 100 patients provides adequate power with 95% confidence interval and ±7% margin of error, accounting for 10% dropout rate.
Expected Impact:
This study will provide the first Korean data on ssRAB performance and safety, potentially establishing evidence for broader implementation of this technology in Korea. The results may contribute to improved diagnostic accuracy for peripheral lung nodules and better patient outcomes through earlier and more accurate diagnosis of lung cancer.
