Evaluating the role of American Thoracic Society/European Respiratory Society/Japanese Respiratory Society/Latin American Thoracic Society high-resolution CT-thorax usual interstitial pneumonitis imaging categories in selecting candidates for transbronchial lung cryobiopsy for undifferentiated interstitial lung disease, a retrospective study.

BACKGROUND

The utility of high-resolution computed tomography-thorax (HRCT) in predicting which subtypes of interstitial lung disease (ILD) require tissue diagnosis with transbronchial lung cryobiopsy (TBLC) is unclear. We aim to see if usual interstitial pneumonia (UIP) imaging categories can inform patient selection for TBLC in undifferentiated ILD.

METHODS

Retrospective study of 76 patients who underwent TBLC for undifferentiated diffuse ILD at a university hospital between 2017 and 2023. HRCT imaging was reviewed on each patient and categorised as per their American Thoracic Society (ATS)/European Respiratory Society (ERS)/Japanese Respiratory Society (JRS)/Latin American Thoracic Society (ALAT) UIP imaging pattern (definite UIP, probable UIP, indeterminate UIP or alternative diagnosis). Chart history/examination, pulmonary function tests, ILD blood-panel, bronchoscopy/bronchoalveolar lavage cellular results and multi-disciplinary team meeting (MDM) discussion were assessed to determine the pre-TBLC diagnostic consensus to include TBLC for further diagnostic accuracy. These were compared against post-TBLC MDM outcomes to confirm if TBLC altered diagnosis and management.

RESULTS

Diagnosis was changed in 43.4% (33/76) of cases post-TBLC. Significantly, TBLC altered the pre-TBLC diagnosis in 65% (13/20) in the indeterminate UIP HRCT category, 41.9% (13/31) in alternative diagnosis, 30% (6/20) in probable UIP and 20% (1/5) in definite UIP categories. There was a confirmed statistical difference between indeterminate UIP and probable UIP patients. TBLC led to a confirmed post-MDM diagnosis in 80.2% of cases, in keeping with international standards.

CONCLUSIONS

TBLC is an effective diagnostic tool in those with indeterminate UIP HRCT patterns. When UIP/idiopathic pulmonary fibrosis (IPF) is felt more likely (probable UIP) on pre-TBLC HRCT, TBLC is less useful.