In patients with idiopathic pulmonary fibrosis (IPF), a correlation has been demonstrated among high-resolution computed tomography (HRCT) lung densitometry, physiologic parameters, and outcomes. A retrospective explorative study on the subject was conducted among patients with IPF who were referred to the Interstitial Lung Disease Clinic at the University Hospital of the Justus Liebig University in Giessen, Germany. Results from the analysis were published in the journal CHEST.

The investigators sought to retrospectively evaluate the relationship among physiologic measurements, patient survival, and HRCT indices in individuals with IPF. A total of 70 patients were enrolled in the study; 48 were men. The mean age of the participants was 66.4±9.0 years. Of the participants, 22 underwent surgical lung biopsy and 48 were diagnosed with IPF using clinical criteria only.

After segmentation of the lungs in thin-section CT in the supine position at full inspiration, the following parameters were evaluated: mean lung attenuation (MLA), skewness, kurtosis, total lung area, peak attenuation, inflexion point with slope, and area right of the inflexion point (AROIP). Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), total lung capacity, diffusing capacity of the lungs for carbon monoxide (DLCO), and 6-minute walking distance test results were analyzed as well.

The strongest association was reported between MLA and FEV1, with an r of −0.63. Moreover, MLA, peak attenuation, slope, attenuation, and AROIP correlated negatively with all physiologic parameters. Further, AROIP was the best predictor of DLCO. An analysis with respect to prediction of mortality demonstrated that AROIP, FVC, and kurtosis were all significantly linked to patient survival.

Among the 70 patients enrolled in the study, 39 died during the follow-up period. According to univariate regression analysis, AROIP was the most significant predictor of mortality among age, sex, MLA, skewness, kurtosis, AROIP, FVC, and DLCO (P <.0001).

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The investigators concluded that the data reported in this study indicate that HRCT indices are associated with physiologic measurements in patients with IPF. Furthermore, the newly defined AROIP measurement has been shown to be of added value for the prediction of DLCO and mortality among patients with IPF. It is believed that CT indices obtained at the time of IPF diagnosis can contribute valuable prognostic information when similar analyses are performed.

Reference

Loeh B, Brylski LT, von der Beck D, et al. Lung CT densitometry in idiopathic pulmonary fibrosis (IPF) for the prediction of natural course, severity and mortality [published online February 8, 2019]. CHEST. doi:10.1016/j.chest.2019.01.019