Chest Flashcards
(231 cards)
what is mosaicism
Mosaicism is defined as patchy difference in attenuation of the lung parenchyma. The crucial factor is the amount of air that is found in each voxel.
what is interstitial thickening?
infiltration of the interstitium by inflammatory tissue, fibrous tissue, cellular infiltrates or fluid, expand the interstium dispacing air from the voxel and increasing the density of the voxel.
what is air space filling?
partial filling of the air spaces with either cells, blood or fluid, displaces air, causing an increase in voxel density. Complete filling of the air spaces leads to consolidation which is not a component of mosaicism.
what is vascular constriction?
vascular constriction, secondary to small airways disease or pulmonary embolic disease, results in a reduction of size of the intralobular interstitium, causing an increase in the amount of air within the voxel. As a result, the density of the voxel decreases.
First question to riase when seeing mosaicism?
is it due to increased or decreased lung density?
how are mosaicism and GGO related?
GGO is a type of mosaicism from high attenuation lung.
How to differentiate types of GGO.
Interstital infiltrate
Partial air space filling
overferfusion
No change to vessels
No change to vessels
Minor increase to vascularity
With lower attenuation lung - work out the difference from
emphysema
pulmonary emboli
small airways disease
emphysema - blood vessels destroyed with lung
PE - vessels attenuated to no flow
Airway disease - reflex vasoconstriction
Why is it important on mosaicism to review the blood vessles of lung parenchyma
if blood vessels are present in normal amounts then you know the parenchyma is more opacified. GGO
if blood vessels are absent in the darker areas then you know it is the darker areas that have lower blood and more likely low attenuation mosaicism and so small airways disease
why does emphysema cause low attenuation of the lung?
due to destruction of lung tissue. As a result there are fewer vessels.
how to differentiate emphysema from small airways disease?
vascular pattern in emphysema becomes disorganised
small airways disease retains a branching pattern but is less obvious
features of a secondary pulmonary lobule?
2-3cm
supplied by a single bronchiole
central artery
venous drainage accumulate in the septa (edges)
what is crazy paving associated with? How sure are we of the association?
associated with alveolar proteinosis
but it is a non specific sign
what happens in the lung during alveolar proteinosis to cause the crazy pave pattern?
proteinacous fluid accumulates in the air spaces and interstitium causing geometric areas of higher attenuation lung (the paving stones - shaded on the image) interspersed with thickened inter and intralobular septa (the gaps between the paving stones - the lines on the image)
other causes of crazy paving pattern?
anything that causes GGO and thickened septa
eg. heart failure, lymphangitis carcinomatosa and non-specific interstitial pneumonitis
what does tree in bud describe?
endobronchial pathology on CT. Multiple centrilobular nodules are seen in a linear branching pattern
how many acini to a secondary lobule?
4 - 8
how big are acini?
6 - 10mm
what do the linterlobular septa contain?
lymphatics
connective tissue
septal veins
Interlobular septal thickening is seen in what conditions?
Lymphagnitis carcinomatosis
pulmonary oedema
aleveolar proteinosis
lipoid pneumoniasarcoidosis
asbestosis
pneumoconiosis
fibrosing alveolitis
how can setpal thickening be characterised?IST
smooth
irregular
modular / beaded
There is a background of fine scattered granuloma nodules. Beading along the oblique fissure is seen (Fig 1a) and is typical of the perifissural distribution, irregualar pattern of IST seen in ……..
sarcoid.
Pulmonary alveolar proteinosis is a rare condition in which…..
the alveoli fill with a lipid rich, periodic acid-Schiff (PAS) positive proteinaceous fluid. The lung interstitium itself remains relatively normal
Lymphangitis carcinomatosis refers to the spread of tumour through the lymphatic system within the lungs. It most commonly occurs in
adenocarcinoma