Diagnostic value of a new cryoprobe for peripheral pulmonary lesions: a prospective study

Cryobiopsy is an established technique that yields larger and higher-quality samples than does a forceps biopsy. However, it remains underutilised in the diagnosis of peripheral pulmonary lesions (PPLs), mainly because of difficulties in handling conventional cryoprobes. A recently introduced single-use cryoprobe with a smaller diameter and more flexibility than conventional ones may improve its diagnostic ability for PPLs. We conducted this prospective study to evaluate the feasibility of transbronchial cryobiopsy in the diagnoses of PPLs, using a new 1.7-mm cryoprobe.

The study included patients with PPLs less than 30 mm in diameter scheduled to undergo bronchoscopy. All the procedures were performed using a combination of virtual bronchoscopic navigation, radial endobronchial ultrasound (R-EBUS) and X-ray fluoroscopy, and all the samples were collected using the cryoprobe alone. Thereafter, we assessed the diagnostic outcomes and safety profiles.

A total of 50 patients were enrolled and underwent cryobiopsy. The median lesion size was 20.8 mm (range, 8.2-29.6 mm), and the negative bronchus sign was seen in 34% of lesions. The diagnostic yield was 94% (95% confidence interval, 83.5-98.8%). A positive bronchus sign had a significantly higher diagnostic yield than did a negative bronchus sign (100% vs. 82.4%; P = 0.035). The yield was achieved regardless of other variables, including lesion size, location, and R-EBUS findings. The major complications were mild and moderate bleeding in 28% and 62% of patients, respectively. Pneumothorax was identified in one patient.

Transbronchial cryobiopsy using the new 1.7-mm cryoprobe is a feasible procedure that has the potential to increase the diagnostic accuracy for PPLs.

Japan Registry of Clinical Trials, jRCT1032200065. Registered July 8 2020, https://jrct.niph.go.jp/en-latest-detail/jRCT1032200065.