Effect of slice thickness on quantitative analysis of interstitial lung disease: a retrospective volumetric chest CT...

High-resolution computed tomography (HRCT) is essential for evaluating interstitial lung disease (ILD). The effect of slice thickness on threshold-based quantification of individual ILD components remains underexplored. This study investigates the effect of slice thickness on ILD quantification using Lung CT Analyzer.

Retrospective analysis of 53 ILD patients (mean age 64.3 ± 14.1 years) who underwent chest CT scans with HRCT (slice thickness ≤ 1.25 mm) and conventional CT (CCT, ≥ 2.5 mm) reconstructions. Quantitative lung volumes, functional parenchyma, emphysema, ground-glass opacity (GGO), consolidation and affected parenchyma were assessed. The effects of contrast media (CM) application and ILD pattern was assessed separately.

Emphysema volume was significantly higher in HRCT compared to CCT for the whole lung (766.9 ± 568.3 mL vs. 482.6 ± 454.4 mL, p < 0.001), the right lung (431.4 ± 314.6 mL vs. 270.2 ± 251.3 mL, p < 0.001), and the left lung (337.3 ± 259.9 mL vs. 228.0 ± 221.5 mL, p < 0.001). Consolidation volumes also differed significantly between HRCT and CCT for the whole lung (271.6 ± 128.4 mL vs. 252.0 ± 126.3 mL, p < 0.001), with similar findings for the right and left lung. Functional volume was underestimated in CCT reconstructions. No significant differences were observed for GGO volumes or overall affected parenchyma. CM application and ILD pattern had no significant interaction on the measurements.

Slice thickness significantly affects the quantification of functional parenchyma, emphysema and consolidation, whereas GGO and the overall ILD extent remain unaffected.