Researchers have discovered that pulmonary vascular volume is associated with the diffusing capacity for carbon monoxide (DLCO) and fibrotic score in idiopathic pulmonary fibrosis (IPF) and published their results in BMC Medical Imaging.

IPF is a difficult disease to diagnose and usually requires multidisciplinary discussion. In addition, the disease course can be unpredictable. Hence, lung function tests are important to monitor IPF. DLCO measures are associated with lung fibrosis and were found to be useful for monitoring disease progression.

Some patients with severe IPF find it difficult to perform conventional lung function tests. Hence, computed tomography (CT) lung volume is often used as a surrogate to evaluate lung function. “As the decline in FVC [forced vital capacity] was used as the physiological marker for disease progression and prognosis prediction, reduced CT lung volume may serve as a quantitative image marker for the same purpose,” Wu and colleagues wrote.


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The authors of this study sought to clarify the relationship between fibrosis, pulmonary vasculature, and lung function in patients with IPF. They recruited participants who were diagnosed with IPF based on multidisciplinary discussions, and pulmonary function tests were carried out, including DLCO.

CT scans covering the lung apex to the lowest hemidiaphragm were performed. All CT images were reviewed by 2 experienced radiologists, and fibrotic scores were estimated through the chest CT scans.

The research team adopted available commercial software for lung segmentation, as well as vessel and emphysema extraction. This was done based on a number of steps of image thresholding and classification. Statistical analysis was then performed to determine if there was a correlation between lung function and CT parameters.

The results demonstrated that higher fibrotic and pulmonary vascular volume (PVV) scores significantly correlated with lower DLCO. However, they were not significantly correlated with FVC. FVC levels were significantly correlated with CT lung volume. A higher PVV score correlated significantly with a higher fibrotic score and pulmonary artery trunk diameter, although the cause for this remains unclear.

Reference

Wu WJ, Huang WM, Liang CH, Yun CH. Pulmonary vascular volume is associated with DLCO and fibrotic score in idiopathic pulmonary fibrosis: an observational studyBMC Med Imaging. 2022;22(1):76. doi:10.1186/s12880-022-00803-8