Cryoprobe Improves Diagnostic Accuracy and Safety in Lung Biopsies

Transbronchial lung biopsy procedures that were performed with a 1.1-millimeter cryoprobe demonstrated higher diagnostic accuracy and safety than two-millimeter forceps in patients with lung nodules or masses and post-lung transplant surveillance, according to a recent randomized trial published in JAMA.

The approach will allow physicians to obtain larger, better‑preserved lung tissue samples while keeping the bronchoscope in place, improving safety and visualization, said Christopher Kapp, MD, assistant professor of Medicine in the Division of Pulmonary and Critical Care and a co-author of the study.

“This cryoprobe makes obtaining larger samples for diagnostic purposes easier. It means less non-diagnostic procedures, faster time to diagnosis and treatment, and less anxiety surrounding the process for both providers and patients. It also makes a previously specialized technology more mainstream and accessible to providers who don’t have the ability to perform complex bronchoscopic procedures,” Kapp said. 

Diagnosing lung disease or assessing a patient’s lungs post-organ transplant requires a bronchoscopic lung biopsy, which involves inserting a camera into the lungs via the mouth or nose and navigating to the abnormality to obtain a small piece of tissue.

Historically, bronchoscopic lung biopsies have been performed with small forceps, which can often result in small specimen sizes and poor specimen quality. When trying to obtain a larger piece of tissue, patients needed a referral to an interventional pulmonologist for a complex bronchoscopic procedure, which uses a larger cryoprobe and can increase complications.

This led to the development of a smaller 1.1-millimeter cryoprobe, which produces freezing at the probe tip and allows for the retrieval of larger, more intact biopsy specimens. This device was approved by the FDA in 2020, and a previous study had shown the cryoprobe’s improved safety compared to forceps.

“As a field of interventional pulmonology, we found a strong need to enhance the biopsy technology and miniaturize the cryoprobe to ensure better samples while improving safety,” said Momen Wahidi, MD, professor of Medicine in the Division of Pulmonary and Critical Care, director of Interventional Pulmonology at Northwestern Medicine and a co-author of the study. 

To evaluate the diagnostic yield of the 1.1-millimeter cryoprobe for transbronchial lung biopsy, a total of 500 patients scheduled to undergo transbronchial lung biopsy for lung nodules or masses, lung transplant, or diffuse parenchymal lung disease at nine U.S medical centers were randomized to undergo the procedure with either the 1.1-millimeter cryoprobe or 2-millimeter forceps.

The primary outcome was diagnostic yield, defined as the percentage of patients for whom the lung biopsy sample led to a specific diagnosis based on histologic examination.

Overall, the cryoprobe produced a significantly higher diagnostic yield than the forceps biopsy and improved diagnostic accuracy by more than 10 percent. The cryoprobe also demonstrated strong safety and patients reported no complications, such as lung collapse or significant bleeding.

“The two most important and perhaps surprising findings were not that the probe was better, but just how much better it was and how safe its use is. Through anecdotal evidence and small non-randomized studies, we figured the technology would perform better, but the magnitude of improvement was quite striking,” Kapp said.

Follow-up analyses, according to the authors, will include subgroup analyses to further understand the impact of this new technology, including lung cancer genetic testing success and cost-effectiveness studies. The authors are also participating in another clinical trial investigating cryoprobe biopsies involving lymph nodes. 

“At Northwestern, we utilize this technology throughout the health system to deliver the highest care to our patients, and to empower our pulmonologists to diagnose lung diseases in an effective and safe manner,” Wahidi added.

This study was investigator-initiated and funded by Erbe Elektromedizin GmbH.