1. Interstitial Lung Disease Patterns
Dr.J.A.Venter
Dept. Imaging Sciences
UFS
2/10/2012

2. Secondary Pulmonary Lobule

3. Centrilobular vs Perylymphatic

4. Lobular Anatomy

5. Secondary Pulmonary Lobule

6. Basic Interpretation What is the dominant HR-pattern: reticular
A structured approach to interpretation of HRCT involves the following questions:
What is the dominant HR-pattern:
reticular
nodular
high attenuation (ground-glass, consolidation)
low attenuation (emphysema, cystic)
Where is it located within the secondary lobule (centrilobular, perilymphatic or random)
Is there an upper versus lower zone or a central versus peripheral predominance
Are there additional findings (pleural fluid, lymphadenopathy, traction bronchiectasis).
Correct diagnosis of IIPs can be achieved only by means of interdisciplinary consensus and stringent correlation of clinical, imaging, and pathologic findings.

7. HRCT Basic Interpretation
Dominant pattern
Reticular vs Nodular
High density vs Low density
Distribution in Secondary Pulmonary Lobule
Centrilobular, Perilymphatic, Random
Distribution within lung
Upper zones , Lower zones
Central or Peripheral

8. Reticular Pattern

9. Reticular pattern
Chest radiographs : collection of innumerable small linear opacities that, by summation, produce an appearance resembling a net .
This finding usually represents interstitial lung disease.
The constituents of a reticular pattern are more clearly seen at thin section CT, whether they are interlobular septal thickening, intralobular lines, or the cyst walls of honeycombing.

10. Chest radiograph shows reticular pattern.
Hansell D M et al. Radiology 2008;246:
©2008 by Radiological Society of North America

11. Interlobular vs Intralobular lines
Interlobular septum
10–20-mm long forming the borders of lobules; perpendicular to the pleura in the periphery. Composed of connective tissue and contain lymphatic vessels and pulmonary venules.
Thin linear opacities between lobules Not usually seen in the healthy lung (normal septa are approximately 0.1 mm thick) but are clearly visible when thickened (eg, by pulmonary edema).
Intralobular lines
visible as fine linear opacities in a lobule when the intralobular interstitial tissue is abnormally thickened .
When numerous, they may appear as a fine reticular pattern. Intralobular lines may be seen in various conditions, including interstitial fibrosis and alveolar proteinosis .

12. Transverse CT scan shows interlobular septum (arrow) in a healthy individual.
Hansell D M et al. Radiology 2008;246:
©2008 by Radiological Society of North America

13. Transverse CT scan shows lntralobular lines.
Hansell D M et al. Radiology 2008;246:
©2008 by Radiological Society of North America

14. Reticular Pattern Septal Thickening Thickened Interlobular Septae
Fibrosis
Smooth
Interstitial pulmonary edema
Lymphangitic spread of carcinoma or lymphoma
Alveolar proteinosis.
Nodular/Irregular
Sarcoidosis
Lymphangitic spread of carcinoma or lymphoma
Silicosis
Honeycombing
UIP

15. PLC

16. Pulmonary Edema

17. Crazy Paving in Alveolar Proteinosis

18. Honeycombing in UIP

19. Nodular Pattern

20. Nodular pattern
Chest radiographs : innumerable small rounded opacities that are discrete and range in diameter from 2 to 10 mm .
The distribution is widespread but not necessarily
uniform.
CT :classified as one of three anatomic distributions:
centrilobular, perilymphatic, or random.

21. Magnified chest radiograph shows a nodular pattern.
Hansell D M et al. Radiology 2008;246:
©2008 by Radiological Society of North America

22. Multiple Small Nodules: Differential Algorithm
Nodules along the pleura and fissures ? NO
YES
Centrilobular Nodules
Patchy : + axial interstitium (>90% fissures or bronchovascular)
Diffuse and Uniform:
Normal axial interstitium(no predominance)
Tree-in-bud
Tree-in-bud absent
Bronchiolar disease
Infectious Bronchiolitis
Bronchopneumonia,TB
Bronchiolar/
Vascular
Disease
Smoker: RB-ILD
Non-smoker:
Subacute HP
BAC,COP,Oedema,
LCH,Vasculitis
Perilymphatic Distribution
Sarcoid
Silicosis/CWP
Lymphangitic Ca
Random Distribution
Metastasis
Lymphangitic Ca
Miliary Infection

23. Nodular Pattern

24. Acinar Nodules

27. Tree in bud Infection Airway disease ABPA Tuberculosis
MAC (mycobacterium avium)
Bacterial, Fungal
Airway disease
Cystic Fibrosis or Bronchiectasis
ABPA
Allergic Bronchopulmonary Aspergilosis (rare)

28. “ Tree in Bud “

30. Increased Density

31. GGO/Consolidation

32. Ground Glass Opacity Acute Chronic Pulmonary edema -Heart Failure
- ARDS
Pulmonary hemorrhage
Pneumonia
- Viral
- Mycplasma
- PCP
Acute Eosinophilic Pneumonia
Hypersensitivity pneumonia
Organizing pneumonia (COP)
Chronic Eosinophilic Pneumonia
Alveolar Proteinosis
Lung Fibrosis
-UIP
-NSIP
Broncho-Alveolar Carcinoma

33. Ground-glass Opacity
Chest radiographs : area of hazy increased lung opacity, usually extensive, within which margins of pulmonary vessels may be indistinct.
CT : hazy increased opacity of lung, with preservation of bronchial and vascular margins . It is caused by partial filling of airspaces, interstitial thickening (due to fluid, cells, and/or fibrosis),partial collapse of alveoli, increased capillary blood volume, or a combination of these, the common factor being the partial displacement of air .
Ground-glass opacity is less opaque than consolidation, in which bronchovascular margins are obscured.

34. Transverse CT scan shows ground-glass opacity.
Hansell D M et al. Radiology 2008;246:
©2008 by Radiological Society of North America

35. GGO: Treatable or Not ? Nonspecific Highly significant
60-80% : active and potentially treatable lung disease % : fibrosis(associated HRCT findings of fibrosis, such as traction bronchiectasis and honeycombing ).

36. GGO

37. Mosaic Attenuation Pattern
Patchwork of regions of differing attenuation that may represent (a) patchy interstitial disease, (b) obliterative small airways disease or (c) occlusive vascular disease .
Air trapping secondary to bronchial or bronchiolar obstruction may produce focal zones of decreased attenuation, an appearance that can be enhanced by using expiratory CT .
The mosaic attenuation pattern can also be produced by interstitial lung disease characterized by ground- glass opacity; in this situation, areas of higher attenuation represent the interstitial process and areas of lower attenuation represent the normal lung.

38. Mosaic Attenuation
Density differences between affected and non-affected lung areas - patchy areas of black and white lung.
The role of the radiologist is to determine which part is abnormal: the black or the white lung
Look at expiratory scans for air trapping
Look at the vessels

39. Transverse CT scan shows mosaic attenuation pattern caused by obliterative small-airways disease.
Hansell D M et al. Radiology 2008;246:
©2008 by Radiological Society of North America

40. Mosaic Attenuation

42. Decreased Attenuation

43. Low Attenuation Pattern

44. Emphysema
Permanently enlarged airspaces distal to the terminal bronchiole with destruction of alveolar walls.
Areas of low attenuation without visible walls as a result of parenchymal destruction.
Centrilobular emphysema
Most common type
Irreversible destruction of alveolar walls in the centrilobular portion of the lobule
Upper lobe predominance and uneven distribution
Strongly associated with smoking.
Panlobular emphysema
Affects the whole secondary lobule
Lower lobe predominance
In alpha-1-antitrypsin deficiency, but also seen in smokers with advanced emphysema
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

47. Cystic Lung Disease
Lung cysts are defined as radiolucent areas with a wall thickness of less than 2mm.
Cavities are defined as radiolucent areas with a wall thickness of more than 2mm and are seen in infection (TB, Staph, fungal, hydatid), septic emboli, squamous cell carcinoma and Wegener's disease.

48. Cyst
Pathology.—A cyst is any round circumscribed space that is surrounded by an epithelial or fibrous wall of variable thickness .
Radiographs/CT:Round parenchymal lucency or low- attenuating area with a well-defined interface with normal lung.
Variable wall thickness but are usually thin-walled (2 mm) and occur without associated pulmonary emphysema .
Usually contain air but occasionally contain fluid or solid material.
Enlarged thinwalled airspaces in patients with lymphangioleiomyomatosis or Langerhans cell histiocytosis
Thickerwalled honeycomb cysts are seen in patients with end- stage fibrosis .

49. Coronal CT scan shows a cyst.
Hansell D M et al. Radiology 2008;246:
©2008 by Radiological Society of North America

50. Cystic disease differential
LAM
LCH
LIP
PCP
Honeycombing

52. Bronchiectasis
Irreversible localized or diffuse bronchial dilatation,usually resulting from chronic infection, proximal airway obstruction, or congenital bronchial abnormality .
Radiographs and CT :Signet ring sign, lack of tapering of bronchi, and identification of bronchi within 1 cm of the pleural surface.
Cylindric, varicose, or cystic, depending on the appearance of the affected bronchi.
Often accompanied by bronchial wall thickening, mucoid impaction, and small-airways abnormalities .
May mimic cystic lung disease and bullous emphysema.
Bronchiectasis caused by primary airway disease should be differentiated from tracion bronchiectasis as a result of fibrosis.

53. Transverse CT scan shows varicose bronchiectasis.
Hansell D M et al. Radiology 2008;246:
©2008 by Radiological Society of North America

54. Honeycombing
Small cystic spaces with irregularly thickened walls composed of fibrous tissue.
Peripheral and subpleural lung regions regardless of the cause. Subpleural several contiguous layers. Distinguished from paraseptal emphysema in which subpleural cysts usually occur in a single layer.

55. Honeycombing
Pathology.—Honeycombing represents destroyed and fibrotic lung tissue containing numerous cystic airspaces with thick fibrous walls, representing the late stage of various lung diseases, with complete loss of acinar architecture. The cysts range in size from a few millimeters to several centimeters in diameter, have variable wall thickness, and are lined by metaplastic bronchiolar epithelium .
Chest radiographs : closely approximated ring shadows, typically 3–10 mm in diameter with walls 1–3 mm in thickness, that resemble a honeycomb; the finding implies end-stage lung disease.
CT : the appearance is of clustered cystic air spaces, typically of comparable diameters on the order of 3–10 mm but occasionally as large as 2.5 cm . Honeycombing is usually subpleural and is characterized by well-defined walls . It is a CT feature of established pulmonary fibrosis .Because honeycombing is often considered specific for pulmonary fibrosis and is an important criterion in the diagnosis of usual interstitial pneumonia , the term should be used with care, as it may directly impact patient care.

56. Transverse CT scan shows honeycombing.
Hansell D M et al. Radiology 2008;246:
©2008 by Radiological Society of North America

58. Zonal Preference

59. Upper vs Lower zone Upper zone Lower Zone Sarcoid Silicosis
Coalworkers Pneumoconiose
Centrilobular Emphysema
Langerhans Cell Histiocytosis
Chron. Hypersens. Pneumonitis
Edema
Panlobular Emphysema
UIP in:
IPF
* Collagen-vascular disease
* Asbestosis

60. Central vs. Peripheral zone
Central zone
Peripheral Zone
Sarcoid
Bronchitis
Pulmonary Edema
COP/OP
Chronic Eosinophilic Pneumonia
Hematogenous Metastases
UIP in:
* IPF
* Collagen - Vascular Disease
* Asbestosis

61. Additional Findings

62. Additional Findings Pleural effusion is seen in: Pulmonary edema
Lymphangitic spread of carcinoma - often unilateral
Tuberculosis
Lymphangiomyomatosis (LAM)
Asbestosis

63. Hilar and mediastinal lymphadenopathy
In sarcoidosis the common pattern is right paratracheal and bilateral hilar adenopathy ('1-2-3-sign'). In lung carcinoma and lymphangitic carcinomatosis adenopathy is usually unilateral. 'Eggshell calcification' in lymph nodes commonly occurs in patients with silicosis and coal-worker's pneumoconiosis and is sometimes seen in sarcoidosis, postirradiation Hodgkin disease, blastomycosis and scleroderma .

64. In Conclusion Know anatomy of secondary pulmonary lobule
Identify Pattern:
Reticular,Nodular, High Attenuation, Low Attenuation
Distribution
Additional Findings

65. References
1. Accessed 2/3/2012
HRCT part I &2
Robin Smithuis, Otto van Delden and Cornelia Schaefer- Prokop Radiology Department of the Rijnland Hospital, Leiderdorp and the Academical Medical Centre, Amsterdam, the Netherlands
2.Diffuse Nodular Lung Disease – A Differential Alogrith:Naidich - MDCT Congress , Sandton,RSA. 16/08/2011
3. March 2008 Radiology, 246, Fleischner Society: Glossary of Terms for Thoracic Imaging