Real-time visualization of lung malignancy with needle-based confocal laser endomicroscopy during shape-sensing robotic-assisted bronchoscopy

Solitary pulmonary nodules (SPN) are commonly encountered in clinical practice. The development of robotic assisted bronchoscopy (RAB) appears promising regarding its diagnostic yield for lung nodules, especially those peripherally located. Confocal laser endomicroscopy (CLE) is an emerging technology that allows high-resolution, in-vivo, real-time assessment of living tissues at a cellular and subcellular level, providing optical biopsies of endoluminal surfaces. Embedding CLE technology on a needle tip (nCLE) allows real-time microscopic analysis of peripheral lung benign or malignant lesions during RAB. The following three cases are the first reported experience of nCLE use during shape-sensing RAB to establish a diagnosis of malignancy in an SPN.

Prior studies demonstrate CLE’s ability to provide real-time optical tissue characterization. CLE has been used to characterize pancreatic lesions and improve differentiation of pancreatic cystic lesions compared to CEA and cytology, and showed comparable accuracy to standard biopsies in esophageal and gastric lesions. In pulmonary applications, probe-based CLE (pCLE) has been explored for airway wall imaging in asthma, detecting acute cellular rejection in lung transplant recipients, and imaging alveolar structures. Lung tissue’s intrinsic autofluorescence (largely from elastin) facilitates CLE, and intravenous fluorescein can augment visualization since malignant nodules often lack autofluorescence. Needle-based CLE (nCLE) has enabled real-time microscopic analysis of peripheral lung cancer; however, its combined use with shape-sensing RAB has been scarcely reported prior to this case series.

Design: Case series of three patients with solitary pulmonary nodules. Setting: Mayo Clinic. Procedure: Under general anesthesia, shape-sensing robotic-assisted bronchoscopy (RAB) was used to navigate to target nodules. Target localization was confirmed with radial endobronchial ultrasound (R-EBUS) and fluoroscopy. Tissue sampling was performed with a 21G needle. Needle-based confocal laser endomicroscopy (nCLE) was used in vivo to assess lesions prior to or during sampling, and systematic mediastinal staging was performed using linear endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA). Stepwise nCLE protocol: (1) Reach target with RAB and confirm with R-EBUS; (2) Administer 2.5 mL of 10% fluorescein intravenously 30 seconds prior to nCLE; (3) Insert <1 mm nCLE fiber through an 18G needle and advance needle to target under fluoroscopy; (4) Puncture target and advance nCLE fiber into lesion to acquire images; (5) Remove nCLE and proceed with planned tissue sampling. Case details: Case 1: 77-year-old woman with a 1.9 × 1.8 cm subsolid RB9 nodule; nCLE showed dark clumps and pleomorphic dark cells; pathology: lung adenocarcinoma. Case 2: 63-year-old woman with a 2.1 × 1.8 cm lobulated RB6 nodule; nCLE showed dark clumps and pleomorphic dark cells; pathology: lung adenocarcinoma. Case 3: 83-year-old man with a 2.6 × 2.2 cm LB9 nodule (SUV 8.1 on FDG PET) and prior RUL squamous cell carcinoma; nCLE showed pleomorphic dark cells; pathology: squamous cell carcinoma. In all cases, mediastinal staging with linear EBUS was performed.

- Three patients with solitary pulmonary nodules underwent simultaneous RAB and nCLE, followed by mediastinal staging. - Demographics: Median age 77 years; 67% male. - Nodule size: Median minimum diameter 1.8 cm; median maximum diameter 2.1 cm. - nCLE imaging: All nodules exhibited abnormal malignant patterns (dark clumps and/or pleomorphic dark cells). - Final pathology: Two primary lung adenocarcinomas and one primary lung squamous cell carcinoma, concordant with nCLE malignant patterns. - Illustrative data: One lesion had SUV 8.1 on PET. - Implication: Combined RAB+nCLE enabled real-time visualization of malignant features and guided successful diagnostic sampling in all cases.

The diagnosis of malignancy in solitary pulmonary nodules often requires tissue confirmation, and accessing peripheral lesions via bronchoscopy can be challenging. Shape-sensing RAB increases reach and stability, potentially improving diagnostic yield, but accurate target confirmation remains critical. Conventional confirmation tools (e.g., R-EBUS) and emerging modalities (augmented fluoroscopy, cone-beam CT) have variable precision. Real-time microscopic visualization with nCLE can provide immediate confirmation of malignant tissue characteristics within the target lesion, potentially improving sampling adequacy and accuracy. Pulmonary tissue’s intrinsic autofluorescence supports CLE imaging, while intravenous fluorescein enhances contrast because malignant nodules may lack autofluorescence. In this series, nCLE patterns characteristic of malignancy (dark clumps, pleomorphic dark cells) were observed in all cases and matched final pathology (two adenocarcinomas, one squamous cell carcinoma). These findings support the concept that combining RAB with nCLE could enhance real-time lesion characterization and optimize biopsy decisions, thus improving diagnostic yield during bronchoscopy for peripheral nodules.

This first reported experience of using needle-based confocal laser endomicroscopy during shape-sensing robotic-assisted bronchoscopy demonstrates feasibility and concordance of real-time nCLE malignant patterns with final pathology in three pulmonary nodules. The combined approach may enhance real-time differentiation of malignant cells and potentially increase sample adequacy, accuracy, and overall diagnostic yield when biopsying suspicious pulmonary lesions.

This is a small, single-center case series (n=3) without a control group, limiting generalizability and precluding statistical assessment of diagnostic yield improvements. Imaging interpretation was not blinded, and standardized performance metrics (sensitivity, specificity) were not evaluated. Procedural details (e.g., 21G vs 18G needles for different steps) may vary across operators and institutions.