Chest radiology II Flashcards
what is a silhouette sign?
two substances of the same radiographic density cannot be differentiated from each other on an x ray
what is the air bronchogram sign?
intrapulmonary bronchi are not visible on the normal CXR because they are filled with air and are surrounded y alveolar air
parenhcymal consolidation may result in visualization of these bronchi since air within the lumens will stand out in contrast to the surrounding opaque lung
air bronchograms are often seen in what conditions?
pneumonia and pulmonary edema
an air bronchogram is indicative of what process?
lesion is within lung parenchyma rather than in pleura or mediastinum (since airways are open)
what are the five mechanisms that cause lung volume loss?
- resporption of air
- relaxation
- scarring
- decreased surfactant
- hypoventilation
what are the only two (natural) things that produce straight lines on CXRs?
fissures
fluid lines
what are the signs of direct lung collapse?
- displacement of interlobar septa (fissures) - most reliable
- loss of aeration of involved lobe
- crowding of the bronchovascular markings
what are the indirect signs of lung collapse?
- elevation of ipsilateral hemidiaphgram
- hilar displacement
- deviation of trachea to side of collapse
- cardiac displacement
- narrowing of rib cage on collapsed side
- compensatory overaeration of normal lung
what makes up acini? what makes up secondary pulmonary lobules?
acini - multiple alveoli
secondary pulmonary lobule - multiple acini
what is the fundamental anatomic unit of the lung?
secondary pulmonary lobule
interstitial pattern can appear in what 3 forms?
generalized thickening
discrete thickening
combination
signs of acute interstitial markings
ill defined and are not distorted (normal branching pattern)
signs of chronic interstitial markings
interstitial markings are sharp and distorted (angular, irregular, or bowed)
what is the most reliable method for distinguishing acute from chronic interstitial changes?
finding an old film for comparison
most diffuse (and chronic) interstitial lung disease is caused by what factor?
fibrosis
focal alveolar consolidation = ?
pulmonary mass or nodule
what are the most common causes of acute diffuse alveolar disease?
bacterial pneumonia
pulmonary edema
where do the pleural spaces extend posteriorly and laterally?
posteriorly - 12th rib
laterally - 10th rib
which film view is most sensitive for detection of small pleural effusions? why?
lateral
can see fluid tracking up major fissure
how does air in the pleural space compare to normal lung air?
pleural space air is more radiolucent
also, no lung markings will be seen
where does the mediastinum go in a tension pneumothorax?
shifts mediastinum away from pneumothorax
what is the most frequent sign of mediastinal disease?
mediastinal widening
what is the most common cause of a middle mediastinal mass?
enlarged lymph nodes
how does LV enlargement appear on PA chest? lateral?
PA - left heart border moves laterally and the cardiac apex moves anterolaterally
lateral view - left heart border moves inferoposteriorly
what is the relationship of lobe vessels in CHF?
upper lobe vessels are larger than lower lobe vessels
what are the most common causes of redistribution or cephalization on CXR?
left heart failure and mitral valve stenosis
what is the downside of CT pulmonary angiogram?
ionizing radiation - significant increase in cancer risk especially in young women (breast cancer)
