INTERSTITIAL LUNG DISEASE HRCT APPROACH.pptx

INTERSTITIAL LUNG DISEASE

1. APPROACH TO INTERSTITIAL LUNG DISEASES

2. Interstitial Disease vs Air Space Disease Interstitial Disease involves the interstitium located between the alveolar air space and blood vessels Air Space Disease involves the alveolar air sacs, often filled with fluid, cells, tumor, pus etc.

3. IMPORTANT CAUSES OF ILD Primary or idiopathic Idiopathic Pulmonary Fibrosis Nonspecific interstitial pneumonia (NSIP) Organising pneumonia (OP) Respiratory bronchiolitis (RB) Diffuse alveolar damage (DAD) Desquamative interstitial pneumonia (DIP) Lymphocytic interstitial pneumonia (LIP)

4. Secondary Causes 1.Infectious Tuberculosis Bacterial Fungal Parasitic Viral 2. Noninfectious Hypersensitivity pneumonitis Pneumoconiosis Drug induced Radiation induced Malignancies

5. Association with diseases of unknown aetiology Sarcoidosis Connective tissue disorders Systemic sclerosis Rheumatoid arthritis Dermatomyositis,Polymyositis SLE Chronic eosinophilic pneumonia

6. Idiopathic Pulmonary Fibrosis (IPF/UIP) Defined as progressive fibrosing interstitial pneumonia of unknown cause. Histo/radio like Usual Interstitial pneumonia Histology suggestive of repeated focal damage to alveolar epithelium. Usually present in older adult, uncommon before 50 yrs. Presents with progressive breathlessness and a nonproductive cough. Clinical findings-clubbing and fine late inspiratory crepts.

7. HRCT - TECHNIQUE Narrow slice thickness (1 mm) at 10 mm intervals. Image reconstruction with high spatial resolution. Generally end inspiration views are taken. One can also take expiration, prone views when required. A window width of 1300, window level of -600 HU is set. No IV injection of contrast is used.

8. Fibrosing vs Non Fibrosing ILD Architectural distortion Traction bronchiectasis Irreversible Loss of volume

9. Common patterns in ILD’s Honeycombing pattern Cystic Pattern Nodular Pattern Mosaic Pattern Reticular Interstitial Pattern Ground glass pattern

10. Honeycomb pattern Cystic airspaces Thick, clearly defined walls Layered along pleural surface Pulmonary fibrosis Seen in : IPF Collagen vascular diseases Asbestosis *Upper lung - sarcoidosis, HP

11. Cystic Pattern Thin walled Circumscribed Air filled Seen in : Langerhans cell histiocytosis Lymphangioleiomyomatosis LIP Collagen vascular disease Emphysema

12. Nodules Perilymphatic Random Centrilobular

13. Nodular Pattern - Random Silicosis/Coal worker’s pneumoconiosis TB/fungal Metastases

14. Nodular Pattern – Centrilobular Subacute hypersensitivity pneumonitis Respiratory bronchiolitis

15. Nodular Pattern - Bronchovascular Lymphoproliferative disorders Lymphangitic carcinomatosi. p for Kaposi sarcoma Sarcoidosis OP

16. Mosaic Pattern Infiltrative disease Small airways disease Pulmonary vascular disease

17. Reticular pattern Caused by thickened interlobular or intralobular septa. infiltration by fibrosis, abnormal cells, or fluid. Interlobular septal thickening is usually described as smooth or irregular. Manifests as a fine reticular pattern on HRCT. Late stage - honeycombing, characterized by cystic airspaces surrounded by irregular walls.

18. Ground glass is defined as a generalized increase in opacity that does not obscure pulmonary vessels. include partial filling of the airspaces, considerable thickening of the interstitium, or a combination of the two.

19. Tree-in-Bud Pattern Centrilobular dots and linear branching opacities Bronchiolar dilatation Bronchiolar impaction Seen in: • АВРА • Cystic fibrosis • Aspiration • Diffuse panbronchiolitis

20. Interlobular septal thickening Marginates secondary pulmonary lobule Contains pulmonary veins and lymphatics Kerley Line

21. Smooth ILS thickening • Pulmonary edema • Infectious pneumonia

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