A new study has determined that between baseline and follow-up high-resolution computed tomography (HRCT), elastic registration is a useful technique for quantifying lung shrinkage in patients with idiopathic pulmonary fibrosis (IPF).

The study, published in European Radiology, also found that the morphological changes identified correlated with pulmonary function tests (PFTs).

“At present, quantitative analysis of IPF with an elastic registration-based method has not been reported,” the authors wrote. “The objective of this study was to evaluate lung shrinking on HRCT scans as a marker of longitudinal changes in IPF and make correlation analysis with disease progression indicators such as PFTs and pulmonary vascular-related parameters.”


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The research team conducted a retrospective study on 69 patients with IPF at a single center between January 2015 and May 2021. The patients were divided into functionally stable and functionally worsening groups, and were further classified into visual improvement and visual worsening groups based on HRCT.

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Elastic registration was performed on the patients’ HRCTs to create deformation maps of each lung, and Jacobian determinants were calculated based on the maps. After logarithmic transformation, the log_jac values were compared with PFTs to determine their level of correlation.

The results showed that the log_jac values were significantly lower in the functionally worsening patients compared with those who were stable, and there was a positive correlation between mean log_jac values and baseline predicted vital capacity and percentage of predicted forced vital capacity.

In addition, log_jac values correlated closely with the number of pulmonary vascular branches and pulmonary vascular volume. The authors conclude that elastic registration is a helpful technique for quantitatively determining the deterioration of lung tissue and vascularization in patients with IPF and may therefore represent a new imaging biomarker in this disease.

Reference

Sun H, Yang X, Sun X, et al. Lung shrinking assessment on HRCT with elastic registration technique for monitoring idiopathic pulmonary fibrosis. Eur Radiol. Published online November 23, 2022. doi:10.1007/s00330-022-09248-7