Analysis of clinical correlation of radiological imaging in idiopathic pulmonary fibrosis by quantitative computed tomography

Purpose: The possibility of evaluating lung damage using quantitative analysis in idiopathic pulmonary fibrosis has caused HRCT to gain more importance in recent years and has been considered as a reasonable indicator of the course of the disease. The aim of this study is to analyze the correlation of radiological imaging performed with HRCT in IPF with clinical tests such as PFT, arterial blood gas(ABG) and 6-min walk test (6 MWT) which are frequently used in the course of the disease, and their results with quantitative computed tomography. Materials and Methods: Patients(n=63) with clinically stable, has a HRCT scan and with PFT, 6 MWT and ABG evaluations within +/- 30 days were included in the study. HRCT quantitative parameters MLD, kurtosis, skewness and % HAA were calculated using DICOM based image processing software with semi-automated lung parenchyma segmentation. Lungs were divided into 3 parts; area above the carina level as upper region, area below the inferior pulmonary vein as lower region and the area between the upper and lower region as the middle region and named as the divided HRCT model. All parameters were calculated for these 3 regions. Demographic information, clinical tests and radiological findings of the patients were analyzed. Results: With spirometric evaluations of cases, negative correlation was found between MLD, % HAA and divided lung densities, a positive correlation was found between all skewness and kurtosis results. There were statistically significant positive correlations between PaO2 with skewness and kurtosis values. There was a significant positive correlation between PaCO2 and upper segment lung density. There was no significant relationship between 6 MWT walking distance and quantitative parameters. While there was a statistically significant relationship between 6 DYT initial SpO2 and MLD, total skewness, total kurtosis, upper-middle segment LD, skewness and upper-middle-lower segment kurtosis, a statistically significant relationship was found between ending SpO2 and all parameters. Conclusion: Lung density, skewness and kurtosis measurements obtained by quantitative analysis of HRCT in IPF cases were found to be correlated with clinical evaluations such as PFT, ABG and 6 MWT. Quantitative analysis, which gives an objective result based on measurability instead of visual evaluation, will provide an opportunity to evaluate the predictive ability of the clinical situation in IPF patients.