Correlation between pulmonary function tests and HRCT indexes in Idiopathic Pulmonary Fibrosis (IPF) patients

Background: correlation between pulmonary function tests (PFTs) and CT-histogram derived indexes is poorly known in Idiopathic Pulmonary Fibrosis (IPF). Objective: To investigate correlation between PFTs (FVC and DLCO) and CT-histogram derived indexes in a cohort of patients (pts) with IPF. Methods: 42 IPF pts having at least two HRCT (baseline and follow-up) and two PFTs available collected no more than 1 month from HRCT evaluation were analyzed. The extent of fibrotic disease was quantified on HRCT examinations calculating Kurtosis, High Attenuation Area (HAA) and Fibrotic Area (FA) indexes. Pearson’s correlation coefficient was performed to assess the strength of association between pulmonary function tests and HRCT indexes. Results: Considering baseline HRCT and PFTs, Pearson correlation analysis revealed moderate correlations between Kurtosis and FVC (r=0.58 with p=0.0001), Kurtosis and DLCO (r=0.52 with p=0.0005), HAA and FVC (r=-0.56 with p=0.0001), HAA and DLCO (r=-0.48 with p=0.0017), FA and FVC (r=-0.56 with p=0.0002), and FA and DLCO (r=-0.49 with p=0.0013). On follow-up, analyzing HRCT and PFTs, Kurtosis and FVC showed a positive strong correlation (r=0.62 with p Conclusions: HRCT quantification indexes showed a moderate or good strength of association with pulmonary function tests; therefore, they may be useful for radiologists in the monitoring of IPF disease.