To analyze the efficacy of quantitative computed tomography (CT) in evaluating and predicting the clinical outcomes of patients with idiopathic pulmonary fibrosis (IPF) for pulmonary fibrosis and emphysema.

Patients diagnosed with IPF in our hospital from January 2021 to April 2024 were retrospectively included. All patients underwent high-resolution CT (HRCT), quantitative CT and pulmonary function tests. Pixels with a degree of emphysema lower than -950 HU were segmented into low attenuation areas (LAA), and the %LAA of each slice was calculated. The degree of fibrotic lesions is that all pixels greater than -700 HU are segmented into highly attenuation areas (HAA), the %HAA is calculated, and the %LAA and %HAA of each thoracic segment are added together to obtain the percentage of abnormal area (%AA). The adverse clinical outcomes were clinical events (hospitalization, acute exacerbation, and death) in patients during the follow-up observation period.

Cluster analysis was conducted based on quantitative CT, pulmonary function tests, and clinical characteristics. Patients in cluster 1 had a higher percent predicted of forced vital capacity (FVC%pred), a lower CT visual score, and lower %LAA and %AA. Among the patients in Cluster 2, the FVC%pred was the lowest and the CT visual score was high. Patients in Cluster 3 had a relatively high FVC%pred, but a high CT visual score, and the %LAA and %AA were also the highest. A total of 35 cases (38.04%) of IPF patients had clinical events. The event-free survival time of patients in cluster 1 was longer than that of patients in clusters 2 and 3 (log rank=6.257, P=0.044; Cluster 1 vs. Cluster 2: log rank=4.921, P=0.027; Cluster 1 vs. Cluster 3: log rank=4.622, P=0.032). However, there was no statistically significant difference in the clinical outcomes between cluster 2 and Cluster 3 (log rank=0.002, P=0.966). Through Spearman rank correlation analysis, %LAA, %HAA, and %AA were all negatively correlated with the percent predicted of diffusing capacity of the lung for carbon monoxide (DL_CO%pred) (rho=-0.407, -0.536, -0.737, P<0.001). The results of the time-dependent receiver operating characteristic curve analysis showed that %AA had a better predictive efficacy for adverse outcomes in IPF patients at 1 year, 2 years, and 3 years [areas under the curves were 0.729(95%CI: 0.681~0.770), 0.852(95%CI: 0.794~0.922), 0.748(95%CI: 0.693~0.796), respectively].

Quantitative CT detection is significantly correlated with the results of pulmonary function tests and the clinical outcomes of patients with IPF. CT quantitative measurement can be used as an effective method to determine the clinical course and prognosis of patients with IPF.