Role of pulmonary function tests and computed tomography volumetric quantitative analysis in assessment of idiopathic pulmonary fibrosis

Abstract

Background Idiopathic pulmonary fibrosis (IPF) is a progressive irreversible lung disease, but early assessment by pulmonary function tests (PFTs) and quantitative volumetric computed tomography (CT) analysis aid in diagnosis, disease monitoring, and prognosis in patients with IPF. Objectives The study aimed to study the role of quantitative volumetric CT indices and PFTs in assessing disease severity in patients with IPF. Patients and methods The study included 40 patients with IPF diagnosed by usual interstitial pneumonia pattern in high-resolution CT and subdivided into two groups according to the GAP staging system (sex, age, and physiology): group I included patients with IPF stage I (five patients) and stage II (15 patients), whereas group II included patients with IPF stage III (20 patients). Clinical history taking, physical examination, plain chest radiography to exclude other diagnosis, PFTs, and quantitative volumetric high-resolution CT were done for all patients. Results There was a significant difference between group I [higher normal attenuating lung volume (NL%) and lower honeycombing area volume (HA%)] versus group II (lower NL% and higher HA%), with no significant difference in whole lung volume (WL) between the two groups. There was a significant correlation between radiological parameters (NL% and HA%) and modified Medical Research Council score of dyspnea and GAP staging system. Radiological parameters (NL% and HA%) had a significant correlation with functional parameters (forced vital capacity% and diffusing capacity for carbon monoxide%). Furthermore, NL% and HA% showed a negative significant correlation with each other. Conclusions PFTs and quantitative volumetric CT parameters showed a statistically significant difference among IPF cases of various severity, and both are highly correlated with each other and with clinical modified Medical Research Council score of dyspnea score of dyspnea and GAP staging system. So, both can play a major role not only in diagnosis but also in detecting severity and predicting mortality in IPF.