Interstitial Lung Abnormalities in the Queensland Lung Cancer Screening Study: Prevalence and Progression Over Two Years of Surveillance.

BACKGROUND: We report the prevalence and progression of incidentally-detected interstitial lung abnormalities (ILA) in the Queensland Lung Cancer Screening Study (QLCSS) cohort.

METHODS: 256 volunteers aged 60-74, with ≥30 pack years smoking history and FEV1≥50% predicted underwent low dose Computed Tomography (CT) chest screening. Electronic search of baseline (T0) and two year follow-up (T2) CT reports identified candidate cases using Fleischner Society interstitial terminology. Candidate CTs were reviewed in a randomised order by two experienced radiologists and a senior respiratory medicine trainee blinded to the existing reports. Scans were evaluated for the presence and extent of ILA using an in-house score, and graded for progression.

RESULTS: ILAs were detected in 20/256 baseline cases (7.8%) with no incident cases detected at T2 surveillance imaging. Of these twenty cases, nine (45%) had reticulation, eighteen (90%) had ground glass change, one had traction bronchiectasis and one had randomly distributed nodularity. Seven cases with ground glass changes also had areas of reticulation, and only two had reticulation alone. All ILAs were graded as minor except for the traction bronchiectasis which was moderate. Only one case progressed on T2 imaging. ILAs were associated with the presence of auscultatory crackles (50%vs11.6%, p=0.001) and a lesser degree of emphysema (mean % volumetric emphysema 6.7%vs9.8%, p=0.009). No relationship was observed between baseline and serial lung function parameters.

CONCLUSIONS: ILAs are frequent incidental findings in lung cancer screening. In the majority of cases these abnormalities do not appear to change significantly over a two-year period of surveillance. This article is protected by copyright. All rights reserved.