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Small airways

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HRCT findings in small airways and understanding basics.

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  • 1. SMALL AIRWAYS DISEASE DR.MITUSHA VERMA DEPT.OF RADIODIAGNOSIS DR.B.NANAVATI HOSPITAL. CHEST RADIO MEET

2. DEFINITION Small airways disease- pathologic condition in which the small conducting airways are affected either primarily or in addition to alveolar or interstitial lung changes. Bronchiolitis- inflammation of small airways Abnormalities of airways 2-3mm in diameter.These small airways form only 10% of total airways resistance. 3. ANATOMY RESPIRATORY BRONCHIOLES-distal to terminal bronchiole, and are airways in which ciliated epithilial lining is interupted by alveoli 13. Lobular bronchiole 14. Terminal bronchiole 15. Respiratory bronchiole 16. Alveolar 17. Atrium 18. Alveolar sac 19. Alveolus 4. CT imaging modality of choice. Can depict subtle abnormalities from tiny nodules to slightly different attenuation Frequently suggestive if not diagnostic Reliable assessment of extent and severity of disease Assessing response to therapy 5. HRCT- Technical aspects High spatial frequency reconstruction algorithm and thin spacing. mAS - 110 kV- 100 Collimation -1.2 Recon- B10f very smooth kernel. Lung window- WW -1200 WC-600 Mediastinal window- WW-400 WC-40 6. An approach to interpretation of HRCT findings. To see into the patho-radiologic classification of these disorders. 7. Anatomic Consideration The bronchiole lumen, wall, alveolar septa airspaces are averaged togather into dark gray background of lung parenchyma. Airways normally visible upto a point midway between hilum &pleural surface. Vessels normally till 5-10mm from pleural surface. 8. SIGNS DIRECT Direct visualisation of diseased bronchioles. INDIRECT Changes in the lung parenchyma distal to the diseased small airway. 9. Direct signs Thickened airway walls Dilated, ringlike tubular or branching tubular structure. If airway is obliterated,bronchiol ar secretions, peribronchiolar inflammation Nodules Linear or branching opacities 10. Indirect signs AIR TRAPPING- mosaic perfusion. SUBSEGMENTA L ATELECTASIS CENTRILOBULAR EMPHYSEMA CENTRILOBULAR AIRSPACE NODULES. 11. AIR TRAPPING 12. SUBSEGMENTAL ATELECTASIS 13. CENTRILOBULAR EMPHYSEMA 14. CENTRILOBULAR AIRSPACE NODULES. 15. Pitfalls Air Trapping vs Patchy ground glass attenuation. 16. Centrilobular emphysema vs cystic lung disease. 17. HRCT CLASSIFICATION TREE IN BUD PATTERN. POORLY DEFINED CENTRILOBULAR NODULES. WITH DECREASED LUNG ATTENUATION. WITH GROUND GLASS OPACITIES AND CONSOLIDATION. 18. TREE IN BUD PATTERN INFECTIONS- tb,mac,viral ,HIV. CYSTIC FIBROSIS Aspiration Connective tissue disorders Asthma ABPA 19. POORLY DEFINED CENTRILOBULAR NODULES Subacute Hypersensitivity Pneumonitis. Respiratory Bronchiolitis with interstial lung siease. 20. WITH DECREASED LUNG ATTENUATION Post transplant constrictive bronchiolitis. Post infectious-Swyer James Syndrome. Toxic fumes inhalation. 21. WITH GROUND GLASS OPACITIES AND CONSOLIDATION Idiopathic bronchiolitis obliterans organising pneumonia. Collagen vascular diseases Radiation therapy. 22. To conclude Small airways disease Thickened airways Obliterated Airways Subsegmental Atelectasis Centrilobular emphysema Centrilobular Nodularities. Air trappeing 23. References HRCT of the Lungs-W.Richard Webb. Imaging Of Small Airways Disease- Radiographics 1996 16:27-41. Radiologic and Pathologic features of Bronchiolitis-AJR:185 Aug 2005. Imaging of the small airways-Johny A Verschakelen.