Role of HRCT in Interstitial Lung Disease with Radiographic Correlation

BACKGROUND Diffuse interstitial lung disease is on the rise in recent times. This could be attributed to number of causes / reasons. Environmental pollution is one of the important causes for the upswing. Increased exposure to inorganic dust, toxic fumes, certain drugs (gold, amiodarone, antibiotics etc.) and radiation can also cause ILD (Interstitial Lung Disease). METHODS This is a hospital based prospective observational study, conducted in the Department of Radiodiagnosis, NSCB Medical College and Hospital, Jabalpur. This study comprised of a total of 50 patients clinically diagnosed interstitial lung disease who had undergone x-ray chest and HRCT (High-Resolution Computed Tomography) Chest examination. RESULTS Incidence of interstitial lung disease was maximum in the middle age group of 51 – 60 years (38 %) with male predominance (58 %). Smoking habit was seen to be associated with 52 % of the cases suggesting association. 8 patients (16 %) had developed diffuse lung disease secondary to connective tissue disorder (rheumatoid arthritis, progressive systemic sclerosis and polymyositis). A confident diagnosis was made on the basis of chest radiograph alone in 11 patients (29 %). Among cases evaluated by HRCT Chest, 41 (82 %) cases showed specific patterns of ILD and nine cases (18 %) showed nonspecific patterns and were classified under unclassified IIP (Idiopathic Interstitial Pneumonia). Out of 41 cases, the most common ILD reported was IPF (20) followed by cases of idiopathic NSI, 8 cases of collagen vascular diseases, 2 cases suggestive of COP / BOOP, and smoking related ILDs were seen in 4 cases, and 2 cases of sarcoidosis were seen in the study. Occupational- and radiation-induced-ILD were seen in one case each. CONCLUSIONS Chest radiography is the initial imaging investigation in the evaluation of diffuse interstitial lung disease. HRCT is the imaging modality of choice to assess interstitial lung disease. It can detect lesion even when the chest radiograph is normal. HRCT can confirm the location, extent of disease, and pattern of disease. HRCT helps in the confident diagnosis of ILD as compared to chest radiography. Thus, it avoids lung biopsy in a large number of patients. HRCT is also useful in assessing the disease reversibility. Follow up of patients is better done by HRCT. KEYWORDS HRCT, Interstitial Lung Disease, Chest X-Ray, Ground Glass Opacity, Honeycombing