Chest X-ray Interpretation Flashcards
What do the shadows tell you on a CRX?
blackest (rays will pass through) to whitest/opaque (rays will be blocked) - air (least dense) => soft tissues/fluids => bone => metal (most dense)
What factors determine the adequacy of a CRX?
projection, inspiration, penetration, rotation
How do you assess projection on a CRX?
PA is standard - heart is closer to the imaging surface => gives a truer image of its actual size
How do you assess rotation on a CRX?
should be centered - medial ends of clavicles are equidistant from the spinous process
How do you assess penetration on a CRX?
vertebral bodies should be just visible through the heart
How do you assess inspiration on a CRX?
8-10 posterior ribs should be visible
What is the appropriate approach to assessing a CRX?
systematic - inside out: heart, medisatinum/hilum, airways/lungs, thoracic wall
What is the size of a normal heart on CRX?
cardiothoracic ratio - the transverse diameter of the heart divided by the diameter of the thoracic cage: < 0.5 is normal (cardiomegaly if > 0.5); should see post pericardial window on cardiac silhouette; should not see enlargement of any chambers
How does the normal hila appear on CRX?
finger width branches pointed down
How does the normal pulmonary vasculature appear on CRX?
lower lobe vessels are larger in size than upper lobe vessels, and all vessels taper gradually from central to peripheral
What does opacity indicate on CRX?
air space disease - pathological process fills alveoli with fluid, pus, blood, or cells (e.g., tumor cells) => distribution may be lobar (pneumonia), diffused (edema), or multifocal (pneumonia or mass)
What is the silhouette sign of pneumonia on CRX?
when two objects of equal density touch each other, the edge or margin between them disappears
What is the spine sign of pneumonia on CRX?
opacity obscures view of the spine
What is the significance of air bronchograms on CRX?
bronchi are not usually visible on CRX - when inflammatory exudate surrounds bronchi (e.g., with pneumonia), bronchi become visible as black tubular structures
What does bat wing opacity on CRX suggest?
pulmonary edema
What is an opacity?
fluid filled alveolus
What is interstitial disease?
abnormal change in supporting structures (alveolar wall) due to inflammation, edema, or fibrosis
What are the most common causes of interstitial disease?
interstitial pneumonia, pulmonary congestion, asbestosis, silicosis, idiopathic pulmonary fibrosis
What are the patterns of interstitial markings?
reticular (fine lines) or nodular (dots)
What is the most common cause of reticular patterns of interstitial lung disease?
pneumonia
How does atelectasis (lung volume loss) appear on CRX?
sharply defined opacification, plate-like or fan-like, no air bronchograms, possible displacement of mobile structures (diaphragm and trachea)
What are the signs of pleural effusion on CRX?
blunting of costophrenic angles (meniscus sign) and Kerley B lines (accumulation of fluids in interlobular spaces)
What are the signs of pneumothorax on CRX?
visceral pleura becomes visible as a thin white line (parallel to the curvature of the chest wall) => absence of lung marking peripheral to the viseral pleural line
How does the diaphragm usually appear on CRX?
right hemi-diaphragm is usually higher, with concave shape and sharp costophrenic angle
What are the common signs of pneumonia on CRX?
segmental/lobar opacity, silhouette sign, spine sign, bronchograms, pleural effusion (usually unilateral)
What are the common signs of pulmonary edema/congestion on CRX?
cardiomegaly, diffused (bilateral) opacities, bronchograms, Kerley B lines, pleural effusion (bilateral)
