Basics of CT Chest

Basics of CT chest

1. Basics of CT Chest Presented by Dr. Mohammad Zannatul Rayhan Pulmonology Phase B Resident MU- XI NIDCH, Mohakhali , Dhaka 4/16/2019 [email protected]

2. Learning objectives Types of CT chest Basic anatomy of CT chest Common pathology in std CT chest HRCT interpretation Common parenchymal pathology in HRCT 4/16/2019 [email protected]

3. 1. Standard or conventional CT: Slice thickness: 3-10 mm scans a large volume, very quickly Covers the full lung +/- contrast 4/16/2019 [email protected]

4. Indications of Std CT Chest: Chest x- ray (CXR) abnormality Lung cancer staging F/U metastases Pleural and mediastinal abnormalities Empyema 4/16/2019 [email protected]

5. 2. High-resolution computed tomography (HRCT) Narrow x-ray beam collimation: 1-1.3 mm vs. conventional 3-10mm Cross sections are further apart: 10 mm High definition images of lung parenchyma: vessels, airspaces, airway and interstitium No contrast 4/16/2019 [email protected]

6. Standard Vs HRCT 4/16/2019 [email protected]

7. Indication of HRCT Chest: Diffusely abnormal CXR Normal CXR with abnormal PFT’s Baseline for patients with diffuse lung disease Solitary pulmonary nodules Reversible (active) vs. non-reversible (fibrotic) lung disease Hemoptysis Follow up known lung disease 4/16/2019 [email protected]

8. 3. CT with contrast 4/16/2019 [email protected]

9. CT Chest Anatomy 4/16/2019 [email protected]

10. CT chest anatomy : views 4/16/2019 [email protected]

11. CT chest anatomy : windows 4/16/2019 [email protected]

12. Hounsfield units 4/16/2019 [email protected]

13. Mediastinum 4/16/2019 [email protected]

14. Supraaortic region 4/16/2019 [email protected]

15. Aortic arch region 4/16/2019 [email protected]

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17. Heart region 4/16/2019 [email protected]

18. Bronchopulmonary segments 4/16/2019 [email protected]

19. At aortic arch level 4/16/2019 [email protected]

20. At left pulmonary artery level 4/16/2019 [email protected]

21. At right pulmonary artery level 4/16/2019 [email protected]

22. At ventricular level 4/16/2019 [email protected]

23. Common Lung pathology in Std CT Chest 4/16/2019 [email protected]

24. Bronchial carcinoma 4/16/2019 [email protected]

25. Bronchial carcinoma 4/16/2019 [email protected]

26. Bronchial carcinoma 4/16/2019 [email protected]

27. Mediastinal tumour 4/16/2019 [email protected]

28. Collapse 4/16/2019 [email protected]

29. Cannon ball sign 4/16/2019 [email protected]

30. Metastasis 4/16/2019 [email protected]

31. Bat's wing appearance 4/16/2019 [email protected]

32. Sarcoidosis 4/16/2019 [email protected]

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34. HRCT interpretation 4/16/2019 [email protected]

35. Relevant anatomy HRCT Interpretation of DPLD is based on the type of involvement of the secondary lobule. Secondary lobule: -smallest lung unit that is surrounded by connective tissue septa. - measures about 1-2 cm -made up of 5-15 pulmonary acini , that contain the alveoli for gas exchange. 4/16/2019 [email protected]

36. Contd .. -supplied by a terminal bronchiole in the center, accompanying centrilobular artery. -pulmonary veins and lymphatics run in the periphery of the lobule within the interlobular septa. - Two lymphatic systems: Central network: runs along the bronchovascular bundle towards the centre of the lobule. Peripheral network: that is located within the interlobular septa and along the pleural linings. 4/16/2019 [email protected]

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38. Centrilobular area: Central part of the secondary lobule. -site of diseases that enter the lung through the airways. ie . hypersensitivity pneumonitis , respiratory bronchiolitis , centrilobular emphysema. Perilymphatic area: Peripheral part of secondary lobule. - site of diseases that are located in the lymphatics / in interlobular septa. ie . sarcoid , lymphangitic carcinomatosis , pulmonary edema. 4/16/2019 [email protected]

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40. HRCT Basic Interpretation Algorithmic approach Dominant HR-pattern Reticular Nodular High attenuation Low attenuation Distribution in secondary lobule Centilobular Perilymphatic Random Distribution within lung Upper zones, lower zones Central, peripheral Additional findings Pleural fluid lymphadenopathy Traction bronchiectasis 4/16/2019 [email protected]

41. Distribution within the Lung 4/16/2019 [email protected]

42. Reticular pattern: Too many lines producing a net like appearance. As a result of thickening of the interlobular septa Due to fluid, fibrous tissue or cellular infiltration in interstitium Or as a result of fibrosis as in honeycombing. 4/16/2019 [email protected]

43. Septal Thickening: Smooth- Lymphagitic spread of carcinoma or lymphoma Interstitial pulmonary oedema Alveolar proteinosis Nodular or irregular- Lymphagitic spread of carcinoma or lymphoma Sarcoidosis Silicosis 4/16/2019 [email protected]

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45. Honeycombing: represents the second reticular pattern recognizable on HRCT. Honeycomb cysts typically occur in several contiguous layers. Pathologically defined by the presence of small cystic spaces lined by bronchiolar epithelium with thickened walls composed of dense fibrous tissue. 4/16/2019 [email protected]

46. Causes of Honeycombing UIP or Interstitial Fibrosis IPF RA, Scleroderma Drug reaction Asbestosis End Stage Hypersensitivity Pneumonitis End Stage Sarcoidosis 4/16/2019 [email protected]

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48. Honeycombing in a patient with UIP 4/16/2019 [email protected]

49. Nodular Pattern : Three categories: according to their distribution A. Random B. Centrilobular C. Perilymphatic Random distribution: -Random refers to no preference for a specific location in the secondary lobule. -Nodules are randomly distributed relative to structures of the lung and secondary lobule. -Nodules can usually be seen to involve the pleural surfaces and fissures, but lack the subpleural predominance. 4/16/2019 [email protected]

50. Centrilobular distribution: - nodules are limited to the centrilobular region. - centrilobular nodules spare the pleural surfaces. -most peripheral nodules are centered 5-10 mm from fissures or the pleural surface. Perilymphatic distribution: - nodules are seen in relation to pleural surfaces, interlobular septa and the peribronchovascular interstitium . -Nodules are almost always visible in a subpleural location, particularly in relation to the fissures. 4/16/2019 [email protected]

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52. NODULAR PATTERN 4/16/2019 [email protected]

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54. Tree in bud: Tree-in-bud describes the appearance of an irregular and often nodular branching structure, most easily identified in the lung periphery. It represents dilated and impacted (mucus or pus-filled) centrilobular bronchioles. 4/16/2019 [email protected]

55. In centrilobular nodules recognition of ' tree-in bud‘ helps to narrowing the D/D. 4/16/2019 [email protected]

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57. Typical Tree-in-bud appearance in a patient with active TB. 4/16/2019 [email protected]

58. High Attenuation Pattern: Ground-glass-opacity (GGO): -Hazy increase in lung opacity without obscuration of underlying vessels -' dark bronchus' sign Consolidation : -increase in lung opacity obscuring the vessels. -' air bronchogram' 4/16/2019 [email protected]

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60. Ground-glass opacity: - result of air space disease i.e.-Filling of the alveolar spaces with pus, edema, hemorrhage, inflammatory or tumor cells. or - result of interstitial lung disease i.e.- Thickening of the interstitium or alveolar walls below the spatial resolution of the HRCT as seen in fibrosis. 4/16/2019 [email protected]

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62. Ground glass opacity 4/16/2019 [email protected]

63. Mosaic attenuation: -density differences between affected and nonaffected lung areas. -there are patchy areas of black and white lung. Less dense More dense Normal area Infiltrative area Air trapped area Normal area Olegamic area Hyperfused area 4/16/2019 [email protected]

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65. Three different causes of mosaic attenuation 4/16/2019 [email protected]

66. Crazy Paving: -combination of ground glass opacity with superimposed septal thickening Crazy paving in alveolar proteinosis 4/16/2019 [email protected]

67. Consolidation: -appears as a homogeneous increase in pulmonary parenchymal attenuation that obscures the margins of vessels and airway walls 4/16/2019 [email protected]

68. Chronic consolidations as a result of COP (cryptogenic organizing pneumonia) 4/16/2019 [email protected]

69. Low Attenuation Pattern: -abnormalities that result in decreased lung attenuation or air-filled lesions. These include: -Emphysema -Lung cysts - Bronchiectasis -Honeycombing 4/16/2019 [email protected]

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71. Emphysema: -areas of low attenuation without visible walls as a result of parenchymal destruction. Centrilobular emphysema: - Most common type - Centrilobular portion of the lobule -Upper lobe predominance and uneven distribution -Strongly associated with smoking. 4/16/2019 [email protected]

72. Centrilobular emphysema due to smoking 4/16/2019 [email protected]

73. Panlobular emphysema: -Affects the whole secondary lobule -Lower lobe predominance -In alpha-1-antitrypsin deficiency, but also seen in smoker. 4/16/2019 [email protected]

74. Paraseptal emphysema: -Adjacent to the pleura and interlobar fissures -Can be isolated phenomenon in young adults or in older patients with centrilobular emphysema -In young adults often associated with spontaneous pneumothorax. Paraseptal emphysema with small bulla 4/16/2019 [email protected]

75. Cystic lung disease: -Lung cyst is radiolucent area with a wall thickness of less than 4mm. 4/16/2019 [email protected]

76. Lung cysts in Langerhans cell histiocytosis 4/16/2019 [email protected]

77. Bronchiectasis : localized bronchial dilatation. The diagnosis is based on a combination of the following findings: -bronchial dilatation ( signet-ring sign) -bronchial wall thickening -lack of normal tapering with visibility of airways in the peripheral lung -mucus retention in the bronchial lumen -associated atelectasis and sometimes air trapping 4/16/2019 [email protected]

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82. Bronchiectasis few having air-fluid levels 4/16/2019 [email protected]

83. cystic cylindrical varicoid 4/16/2019 [email protected]

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