Part 2 Radiological Presentation of Infectious Diseases Flashcards
What are the routes of infection of pneumonia?
> Tracheobronchial tree - most common route
> Hematogenous
> Direct from neighboring organs
What is the most common route of infection in pneumonia?
Tracheobronchial tree
What are the 3 broad imaging findings in pneumonia?
> Consolidation / Lobar pneumonia
> Bronchopneumonia
> Interstitial pneumonia
Consolidation / Lobar pneumonia is caused by what?
> Pneumococcal
> Klebsiella
Bronchopneumonia is caused by what?
> Staphylococcus
> Streptococcus pyogenes
Interstitial pneumonia is caused by what?
> Viral
> Mycoplasma pneumonia
> PCP /Pneumocystis jirovecii pneumonia
Pneumococcal and Klebsiella causes why type of pneumonia?
Consolidation / Lobar pneumonia
Staphylococcus and Streptococcus pyogenes causes what type of pneumonia?
Bronchopneumonia
Viral, Mycoplasma pneumonia, and PCP /Pneumocystis jirovecii pneumonia causes what type of pneumonia?
Interstitial pneumonia
Where does the infection start & spread in consolidation / lobar pneumonia? What part of the lungs does it involve?
> Infection starts in the alveoli and spreads to other alveoli
> It generally involves one whole lobe of the lung.
Where does the infection start & spread in bronchopneumonia?
> Infection starts in the bronchioles, and then it spreads to the alveoli.
Where does the infection start in interstitial pneumonia? What is its effect on the affected tissue?
> Interstitium gets infected and it becomes thickened because of the fluid present in the interstitium.
What is the supporting tissue for blood vessel and lung parenchyma?
Interstitium
What is the insterstitium?
It is the supporting tissue for blood vessel and lung parenchyma.
In consolidation pneumonia, there is replacement of air in alveoli with what?
> Fluid
> Pus
> Debris
In consolidation pneumonia, disease spreads by ___ and ____ through the interalveolar and interbronchiolar spaces.
> Pores of Kuhn
> Channels of Lambert
Opacification continues until it reaches the fissure
Lobar pneumonia
What is the air-bronchogram sign?
Bronchioles remain filled with air (dark appearance)
What do you call it when bronchioles remain filled with air?
Bronchogram sign
How does consolidation pneumonia appear on x-ray?
> Homogenous opacity obscuring the vessels
> Lobar opacification sharply defined at the fissures
> Segmental opacification due to early initiation of antibiotic treatment
> Air bronchograms
> Silhouette sign
> No volume loss
What is the Silhouette sign?
Loss of lung / Soft tissue interface
e.g. You are not able to see the silhouette of the lung and cardiac border because they are appearing on the same density.
Segmental opacification is due to what?
Early initiation of antibiotic treatment
What is the main difference between seeing opacities in lung collapse and consolidation pneumonia?
In consolidation pneumonia, you can see the air bronchogram and you can see that the upper lobe still maintain its size.
In consolidation pneumonia, when there is a patch of opacity in the right lower lung field, how would you know if the lobe affected is the middle or the lower lobe on PA or AP view?
Reference points:
> Costophrenic angles
> Diaphragm
> Right heart border
If you can see the costophrenic angles and diaphragm, but the right heart border is NOT visualized, then this is consolidation pneumonia in the RIGHT MIDDLE LOBE.
But if you did not see the hemidiaphragm on the right side, this infection would have been in the RIGHT LOWER LOBE.
Differential diagnosis for consolidation pneumonia
> Edema
> Hemorrhage
> Tumor
Disease process in bronchopneumonia starts in the bronchioles as what?
Acute bronchitis
In bronchopneumonia, there is presence of air bronchogram. True or False?
FALSE. There is NO presence of air-bronchogram in bronchopneumonia.
Discuss the disease process of bronchopneumonia.
> Disease process starts in the bronchioles as acute bronchitis and because of this, there is no air-bronchogram. The disease then spreads to the alveoli and causes opacification.
> Disease process may start in several segments at the same time and in both lungs .
> Opacification may be focal but progress to be diffuse; do not cross fissures
Describe the opacification in bronchopneumonia.
Opacification may be focal but progress to be diffuse; do not cross fissures
What are the differentials of multi-focal consolidations?
> Septic emboli
> Metastases
> Lymphoma
What are the differentials of diffuse consolidation in bronchopneumonia?
> Edema (most common cause)
> Hemorrhage
> Lymphoma
Type of pneumonia where there is involvement of the supporting tissues of the lung parenchyma and vasculature
Interstitial pneumonia
Ground glass haziness is seen in what type of pneumonia?
Interstitial pneumonia
Type of pneumonia that appears as reticular and nodular opacities
Interstitial pneumonia
Describe the appearance of interstitial pneumonia on x-ray
> Ground glass haziness
> Fine nodular interstitial opacities
> Reticulonodular opacities
What are the differentials for interstitial pneumonia?
> Interstitial edema in heart failure
> Lymphangitis
> Carcinomatosis
Lung abscess is most commonly due to what?
> Staphylococcus aureus
> Klebsiella
> Pseudomonas
It generally takes how many days for pneumonia to develop abscess formation?
7 to 14 days depending on the infecting agent
Describe the appearance of lung abscess on x-ray.
> Cavity containing AIR-FLUID LEVEL
> Round in shape - appear similar on frontal and lateral projections
> Margins are equally well seen on all sides.
It is the most sensitive and specific imaging modality to diagnose lung abscess.
CT scan
Why is contrast administration recommended for CT scan of lung abscess?
To outline the abscess margins
Wall is typically thick and luminal surface irregular in this lung condition
Lung abscess
Bronchial vessels and bronchi may be traced as far as the ___ of lung abscess
Wall
