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Small airways
Small airways disease refers to pathologies that affect the small conducting airways less than 3mm in diameter. CT scanning is the imaging modality of choice for evaluating small airways disease. On HRCT, direct signs of small airways disease include thickened airway walls, dilated or obliterated airways, and nodules. Indirect signs include air trapping, subsegmental atelectasis, centrilobular emphysema, and centrilobular nodules. Common patterns seen on HRCT include tree-in-bud, poorly defined centrilobular nodules, decreased lung attenuation, and ground glass opacities with consolidation.
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Small airways
- 1. SMALL AIRWAYS DISEASE DR.MITUSHAVERMA DEPT.OF RADIODIAGNOSIS DR.B.NANAVATI HOSPITAL. CHEST RADIO MEET
- 2. DEFINITION… Small airwaysdisease- 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 terminalbronchiole, 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 – imagingmodality 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 approachto interpretation of HRCT findings…. To see into the patho-radiologic classification of these disorders.
- 7. Anatomic Consideration… Thebronchiole 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 visualisationof diseased bronchioles. INDIRECT Changes in the lung parenchyma distal to the diseased small airway.
- 9. Direct signs Thickened airwaywalls Dilated, ringlike tubular or branching tubular structure. If airway is obliterated,bronchiol ar secretions, peribronchiolar inflammation Nodules Linear or branching opacities
- 14. Indirect signs AIR TRAPPING- mosaicperfusion. SUBSEGMENTA L ATELECTASIS CENTRILOBULAR EMPHYSEMA CENTRILOBULAR AIRSPACE NODULES.
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- 19. Pitfalls… Air Trappingvs Patchy ground glass attenuation.
- 20. Centrilobular emphysemavs cystic lung disease.
- 22. HRCT CLASSIFICATION… TREE INBUD PATTERN. POORLY DEFINED CENTRILOBULAR NODULES. WITH DECREASED LUNG ATTENUATION. WITH GROUND GLASS OPACITIES AND CONSOLIDATION.
- 23. TREE IN BUD PATTERN•INFECTIONS- tb,mac,viral ,HIV. • CYSTIC FIBROSIS • Aspiration • Connective tissue disorders • Asthma • ABPA
- 25. POORLY DEFINED CENTRILOBULAR NODULES •Subacute Hypersensitivity Pneumonitis. • Respiratory Bronchiolitis with interstial lung siease.
- 26. WITH DECREASED LUNG ATTENUATION •Post transplant constrictive bronchiolitis. • Post infectious-Swyer James Syndrome. • Toxic fumes inhalation.
- 27. WITH GROUND GLASS OPACITIESAND CONSOLIDATION • Idiopathic bronchiolitis obliterans organising pneumonia. • Collagen vascular diseases • Radiation therapy.
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- 31. References HRCT ofthe 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.