Safety Profile of Ultrasound-guided Transparietal Lung Biopsy in Patients With Diffuse Interstitial Lung Disease

Rationale Interstitial lung diseases (ILDs) require accurate histological diagnosis when imaging is inconclusive, yet current techniques-surgical lung biopsy and transbronchial cryobiopsy-carry significant risks and lack real-time guidance. BPTE, widely used in oncology, provides ultrasound-guided sampling under local anesthesia with historically lower complication rates, but its value in ILD remains unproven. The TOUCANS study aims to generate safety and feasibility data to support its potential use as a less invasive diagnostic alternative.

Objectives The primary objective is to assess the safety of BPTE in ILD patients, focusing on major adverse events: death, pneumothorax requiring drainage, hemorrhage requiring intervention, and prolonged pleural drainage. Secondary objectives include evaluating all complications within two months, comparing BPTE histological quality with surgical biopsy, and assessing pain, dyspnea, analgesic use, healing, drainage duration, and hematoma on thoracoscopic imaging.

Materials and Methods Fifteen patients aged 18-75 with ILD requiring tissue diagnosis after multidisciplinary review will be included. Exclusion criteria cover coagulation disorders, severe comorbidities, long-term oxygen therapy, impaired lung function, obesity, pulmonary hypertension, anesthetic allergy, and vulnerable populations. BPTE will be performed 2-4 weeks before surgical biopsy, under local anesthesia and spontaneous ventilation, with CT- and ultrasound-guided targeting. One or two biopsies will be taken, followed by ultrasound and chest X-ray monitoring; discharge occurs after four hours if stable. Surgical thoracoscopic biopsy will then be carried out with standard postoperative care. Pain, dyspnea, healing, and imaging findings will be recorded, and histological samples will be reviewed blindly. Data will be captured in eCRFs according to GDPR/CNIL requirements.

Expected Outcomes TOUCANS will provide the first prospective evidence on BPTE for ILD. Demonstrating safety and adequate diagnostic yield could position BPTE as a minimally invasive, outpatient, ultrasound-guided alternative to surgical biopsy. This may shorten diagnostic pathways, reduce complications, and offer a viable option for patients unsuitable for surgery, ultimately improving early management and prognosis.