B41-43 Pleural Thickening and Irregularity Scores on Lung Ultrasound for Differentiating IPF and NSIP: A Cross-sectional Study

Abstract Background IPF typically shows a subpleural predominance, whereas NSIP often exhibits relatively homogeneous intrapulmonary fibrosis; therefore, evaluation of the subpleural region is essential. However, a modality that directly assesses subpleural morphology has not been firmly established. In interstitial lung disease, studies using lung ultrasound (LUS) have increasingly focused on B-lines, but few have specifically examined pleural-line morphology—namely, pleural thickening and pleural irregularity. We investigated whether LUS-derived pleural findings can aid in differentiating IPF from NSIP. Methods We conducted a cross-sectional study including 20 patients with IPF and 20 with NSIP, with diagnoses confirmed by multidisciplinary discussion. Based on HRCT findings, two sites per patient were selected—one with an advanced parenchymal lesion and one with an early (relatively mild) lesion. At each site, pleural thickness and pleural irregularity were assessed. Pleural thickness and Pleural irregularity was graded on four levels: normal, border, moderate, and severe. The trend of pleural thickening and pleural irregularity were evaluated separately in advanced and early lesions to assess differences between IPF and NSIP. The relationship between pleural thickening and pleural irregularity was evaluated using multivariate analysis of variance to determine whether their combination could differentiate IPF from NSIP. Results Pleural thickening was more prominent in IPF than in NSIP in both advanced and early lesions, whereas many NSIP cases remained within the normal range. (both p 0.001 ) Pleural irregularity was more pronounced in NSIP, while most IPF cases remained border, in advanced lesions(p = 0.001) ; in early lesions, both groups were mainly border without significant difference(p = 0.166). This analysis demonstrated that IPF tended to show greater pleural thickening, whereas NSIP showed more pronounced pleural irregularity, and that pleural thickening and irregularity showed a weak negative correlation. MANOVA demonstrated a significant group effect(p 0.001), revealing disease-specific characteristics: IPF exhibited marked pleural thickening with limited pleural irregularity, whereas NSIP showed pronounced pleural irregularity with little pleural thickening. Conclusion Pleural thickening and irregularity showed disease-specific patterns distinguishing IPF and NSIP, reflecting their underlying pathological differences. LUS may serve as a simple and clinically valuable adjunct in the differential diagnosis of interstitial lung diseases. This abstract is funded by: None