1. The document provides guidance on interpreting chest CT scans by describing common patterns seen in interstitial lung diseases. 2. It outlines different types of nodules seen on CT scans including dot-like, ill-defined centrilobular, and tree-in-bud nodules and associates each with specific conditions. 3. The document also discusses the distribution of nodules and how this can provide clues to different diseases, such as perilymphatic nodules suggesting sarcoidosis.

1. HOW READ CHEST CT -3
ANAS SAHLE ,MD

2. Basic elements
Appearance
pattern
Distribution
Patient data
pattern
Ct
interpretation

3. FIGURE 17.3. HRCT Findings in
Interstitial Lung Disease
1- Interlobular (Septal) Lines
2-Intralobular Lines
3-Thickened Fissures
4-Thickened bronchovascular
structures Dot lik
5-Centrilobular (Lobular tree-in-bud
Core) Abnormalities lldefined
6- Subpleural lines
7-Parenchymal bands
8-Honeycombing
9-Thin-walled cysts
10-Irregularity of Lung Interfaces
11-Ground-Glass or Hazy
Increased Density
12-Architectural Distortion and
Traction Bronchiectasis
13-Conglomerate Masses
14-Consolidation

4. Appearance pattern
Increased Decreased
Nodular Linear
lung lung
opacities opacities
attenuation attenuation

5. Increased lung attenuation
Ground-glass opacity
Consolidation

6. Nodular pattern
Size
Appearance
Attenuation
Distribution

7. WHAT IS DOMINANT PATTERN ?

8. B-Nodules

9. B-Nodules
1-Dotlike Fig. 6.21a,b. (Peri)lymphatic (a) vs
centrilobular (b) distribution of
disease. (a) Patient with sarcoidosis
showing numerous subpleural and
fissural nodules. Since nodules are
also found in other areas where
lymphatics are located
(peribronchovascular
interstitium, interlobular septa and
centrilobular) diagnosis
of disease with a (peri)lymphatic
distribution can be made. (b)
Patient with infectious bronchiolitis
(tuberculosis) showing centrilobular
changes (nodules, branching lines
and tree-in-bud), suggesting disease
that predominantly involves the
airways
DOTLIKE :
1- pulmonary edema,
2-lymphangitic carcinomatosis,
3-UIP

10. B-Nodules
2- Ill-defined (Ground-Glass) centri-lobular nodules
FIGURE 17.7.
Centri-lobular Ground-Glass Nodules in
Sub-acute Hypersensitivity Pneumonitis.
HRCT shows the typical poorly defined
centri-lobular nodules (arrows) of subacute
hypersensitivity pneumonitis (bird-fancier's
lung).
Caption: Picture 5. High-resolution chest CT
scan of a patient with hypersensitivity
pneumonitis demonstrates centrilobular
nodules. These nodules are unlike those of
sarcoidosis, in which the nodules are
subpleural and along peribronchovascular
interstitium
Ill-defined (Ground-Glass) centri-lobular
nodules represent disease of the bronchiole
and adjacent parenchyma :
1- subacute hypersensitivity pneumonitis
2-cryptogenic organizing pneumonia (COP),

11. B-Nodules
3-tree-in-bud appearance
Figure 2. Postprimary active tuberculosis in a
66-year-old woman with a chronic cough.
High-resolution CT scans of the right lung
show peripheral, poorly defined, small (2–4-
mm-diameter) centrilobular nodules and
branching linear opacities of similar caliber
originating from a single stalk (the tree-in-bud
pattern) in the lower lobe (arrow)

12. B-Nodules
Centri-lobular (Lobular Core) Abnormalities
Tree-in-bud almost always indicates the presence of:
1. Endobronchial spread of infection (TB, MAC, any bacterial bronchopneumonia).
2. Airway disease associated with infection (cystic fibrosis, bronchiectasis).
3. less often, an airway disease associated primarily with mucus retention (allergic
bronchopulmonary aspergillosis, asthma).
(Mycobacterium Avium
Complex Disease)
Typical Tree-in-bud appearance in a patient
with active TB.

13. Nodules
Dot-like tree-in-bud Ill-defined
• pulmonary edema. appearance centrilobular
• lymphangitic carcinomatosis. • Tree-in-bud almost always nodules
• UIP indicates the presence of:
represent disease of the
• Endobronchial spread of bronchiole and adjacent
infection (TB, MAC, any parenchyma:
bacterial bronchopneumonia)
• in subacute hypersensitivity
• Airway disease associated
pneumonitis
with infection (cystic fibrosis,
bronchiectasis) • cryptogenic organizing
pneumonia (COP).
• less often, an airway disease
associated primarily with
mucus retention (allergic
bronchopulmonary
aspergillosis, asthma).

14. B-Nodules
Nodular distribution

15. B-Nodules

16. B-Nodules
Algorithm for nodular pattern

17. B-Nodules
sarcoidosis
•Nodules predominating in the
peribronchovascular, interlobular, and
subpleural regions those portions of
the interstitium where the lymphatics
lie are said to have a perilymphatic
distribution
Sarcoidosis: typical presentation with nodules along
the bronchovascular bundle and fissures Notice the
partially calcified node in the left hilum.

18. sarcoidosis

19. 1-WHAT IS DOMINANT PATTERN ?
2- Where is it distribution within lung

20. LEFT: miliary TB
RIGHT: metastases

21. B-Nodules
4-Conglomerate
Masses
FIGURE 17.10. Nodules and a Conglomerate
Mass in Silicosis. A. Posteroanterior radiograph of
a 79-year-old patient with silicosis shows diffuse
nodules as well as a conglomerate mass in the
right upper lobe (arrow). B. HRCT scan through
the upper lobes shows peribronchovascular and
subpleural micronodules (small arrows), larger
nodules (curved arrow), and a conglomerate
mass representing progressive massive fibrosis in
the right upper lobe (large arrow). The pleural
effusions are caused by concomitant congestive
heart failure.
Conglomerate Masses:
1- Sarcoidosis
2-Silicosis 3-CWP 4-Radiation fibrosis
These conglomerate masses are most often seen in
patients with end-stage sarcoidosis but can occur in
complicated silicosis with progressive massive fibrosis
(PMF) (Fig. 17.10) or radiation fibrosis

22. NODULAR PATTERN
Sub-pleural nodules
Absent Present
Random ,
Centri-lobular distribution uniform
distribution
ALSO
Peri-bronchovascular
Septal
Tree in bud Random
Centri-lobular Peri-lymphaatic
Tree in bud absent
present patchy distribution
In distribution distribution
Peri-bronchiolar peri-vascular Peri-bronchiolar
diseases diseases diseses

23. Regional distribution
(nodular pattern)
Upper lung Lower lung Diffuse
• Histiocytosis • Asbestosis • Hypersensitivity
• Sarcoidosis • Organising pneumonitis
• Silicosis pneumonia • Diffuse
• Pneumocoinosis • Hematogenous pneumonia
• Tuberculosis metastases • Lymphangitic
• Alveolar spread of tumor
• RB-ILD
hemorrhage • Hematogenous
metastases
• Sarcoidosis

24. Regional distribution
(nodular pattern)
Central lung Peripheral lung
• Sarcoidosis • Asbestosis
• Silicosis • Organising pneumonia
• Pneumocoinosis • Hematogenous
• Lymphangitic spread of metastases
tumor • Hypersensitivity
pneumonitis
• NSIP
• Septic emboli
• Small airway disease

25. Regional distribution
(nodular pattern)
Uni-lateral
Posterior lung
asymetric
• Sarcoidosis • Pneumonia
• Silicosis • Sarcoidosis
• Pneumocoinosis • Lymphangitic
• Asbestosis spread of tumor
• Hypersensitivity
pneumonitis