Feasibility of novel endoscopic imaging techniques during transbronchial lung biopsy in interstitial lung disease

Interventional - single-arm study Exposure: endoscopic imaging of the lung parenchyma using confocal laser endomicroscopy (CLE) and radial endobronchial ultrasound (radial EBUS) in unclassifiable interstitial lung disease (ILD) prior to undergoing transbronchial lung cryobiopsy (TBLC). • Patients with unclassifiable ILD who have been referred for TBLC will be enrolled. • All procedures will be performed by two respiratory physician bronchoscopists, one of whom has extensive experience in the performance of TBLC. • Participant recruitment is estimated to take up to 6 months in duration. • Participants will undergo a TBLC procedure following standard practice at the treating institution (compliant with international expert guidelines on the performance of cryobiopsy). Three ipsilateral target sites for TBLC will be selected prior to the procedure after review of CT imaging and discussion at an interstitial lung disease multidisciplinary meeting. They will be performed under fluoroscopy guidance and general anaesthesia. • Prior to the biopsies being taken, all the target sites will be viewed with (1) radial EBUS, followed by (2) CLE. The recorded images will not be used to guide the site of biopsy selection. Images will be compared to final histologic findings. • The radial EBUS component will involve interrogation of the target site distal airway (approximately the distal 3cm) with the EBUS probe. CLE will involve interrogation of the same airway segment with a thin, flexible endomicroscopy probe that is inserted through the working channel of the bronchoscope. The position of both probes will be confirmed on fluoroscopy. • The combined time of radial EBUS and CLE in addition to the standard TBLC is estimated to be 15 minutes. The baseline average duration of TBLC is 45 minutes. • Adherence to the intervention protocol will be documented by in the record of the crobiopsy session, including identification of all biopsy sites with and the related imaging findings from the various imaging modalities. • No specific contrast dyes or other markers will be administered to participants. Patients with unclassifiable ILD who have been referred for TBLC will be enrolled. Three target sites for biopsy will be examined with radial EBUS then CLE prior to TBLC at the same location under fluoroscopy guidance. Imaging findings on radial EBUS and CLE will be compared to histologic findings.