An observational study published in the journal European Radiology found that serial decline in computed tomography (CT) markers of lung volume—specifically, annualized 25% reduction in aortosternal distance (ASD)—provides evidence of disease progression in patients with idiopathic pulmonary fibrosis (IPF). This evidence, the study notes, is not always identified by forced vital capacity (FVC) trends or changes in the fibrosis extent.
A few other key conclusions the study draws are:
• Serial decline in automated and surrogate markers of lung volume on CT corresponds to changes in FVC.
• Annualized reductions in the distance between the ascending aorta and posterior border of the sternum on CT predict mortality beyond annualized percentage change in FVC.
Read more about the diagnosis of IPF
The baseline cohort of the patients examined in the study (a total of 273) has been previously studied, in a publication that focuses on the value of the CT markers of lung volume at a single point in time. While 5 previous publications from members of this group (Jacob et al) examine the automated textural analysis of lung fibrosis in IPF, none of them concern themselves with lung volumes, including the CT surrogates for lung volumes that are described in this study, and their impact on predicting mortality.
A group of researchers led by Dr. Hasti Robbie, consulting radiologist at King’s College Hospital, London, England, analyzed serial CTs for progressive volume loss or fibrosis progression in 81 IPF patients (median age, 67 years) with FVC. These serial CT measurements comprised oblique fissure posterior retraction distance (OFPRD), ASD, lung height corrected for body habitus (LH), and automated CT-derived total lung volumes (ALV).
A total of 58 (72%) of all patients under observation died. It was observed that the annual percentage change in ALV was most significantly related to the annual percentage change in FVC. On multivariate analysis, the annual percentage change in ASD predicted mortality, but the change in FVC did not.
It was cohesively concluded that “a 25% decline in annual [percentage] change in ASD best predicted mortality, superior to [a] 10% decline in FVC and fibrosis progression.”
Robbie H, Wells AU, Fang C, et al. Serial decline in lung volume parameters on computed tomography (CT) predicts outcome in idiopathic pulmonary fibrosis (IPF). Eur Radiol. Published online October 30, 2021. doi:10.1007/s00330-021-08338-2