Quantitative CT-derived vessel metrics in idiopathic pulmonary fibrosis: A structure-function study

Area of Science:

• Pulmonary Medicine
• Radiology
• Medical Imaging Analysis

Background:

• Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with complex pathophysiology.
• Assessing lung vessel morphology is crucial for understanding IPF progression and severity.
• Current methods for quantifying lung vasculature may be limited.

Purpose of the Study:

• To investigate the association between quantitative lung vessel morphology, determined by a novel automated algorithm, and functional indices in IPF patients.
• To evaluate the utility of a new fully automated algorithm for quantifying vessel metrics in IPF.
• To explore the relationship between specific vessel metrics (volume, density, tortuosity, heterogeneity) and lung function tests.

Main Methods:

• Computed tomography (CT) images from 152 IPF patients were analyzed using a fully automated algorithm to quantify vessel volume, density, tortuosity, and heterogeneity.
• Pulmonary artery and vein metrics were separately quantified in a subset of 106 patients.
• Quantitative vessel metrics were correlated with standard lung function test results, including forced vital capacity (FVC), diffusion capacity for carbon monoxide (DLCO), total lung capacity (TLC), and composite physiologic index (CPI).

Main Results:

• Normalized vessel volume showed moderate correlations with FVC, DLCO, TLC, and CPI on univariable analysis.
• Normalized vessel volume was correlated with vessel density but not heterogeneity.
• On multivariable analysis, normalized vessel volume and vessel heterogeneity independently predicted DLCO, TLC, and CPI, indicating distinct contributions to lung damage.
• Artery-vein specific metrics did not provide additional information beyond whole vasculature analysis.

Conclusions:

• The new automated algorithm effectively quantifies lung vessel morphology in IPF, confirming previous findings on the link between vessel volume and disease severity.
• Normalized vessel volume and vessel heterogeneity, as determined by the new tool, independently associate with key functional indices in IPF.
• Quantitative vessel metrics derived from CT imaging may not directly reflect vasculopathic damage in IPF but are linked to overall lung function impairment.