silhouette sign
Radiopacity which causes obliteration of part of or all of the heart border
can you tell the difference btwn hemorrhage or PNA on a chest x-ray?
No! Just see an opacity.
air bronchogram sign
when you have fluid in the alveoli and therefore you can see the air in the bronchi
5 mechanisms of volume loss in the lung
- resorption of air as a result of obstruction
- relaxation o flung due to air/fluid in pleural space
- scarring causing lung retraction
- decreased surfactant
- hypoventilation in CNS depression or pain
How do the fissures change in event of lung collapse? (direct signs)
RUL: minor fissure superior/major anterior
RML: minor down/major superior
RLL: major posterior/inferior - spine gets lighter
LUL: major anterior
LLL: major - thick opaque straight line, spine gets lighter
what are some direct signs of lung collapse?
fissure movement and crowding of the bronchovascular markings in the affected lobe
what are some indirect signs of collapse?
- right hilum is higher than left
- deviation of trachea to side of collapse
- cardiac displacement to side of collapse
- narrowing of the rib cage
- compensatory overaeration of adjacent lung
what are the 2 things that cause straight lines on an xr?
- fluid-air levels
2. fissures
name 4 factors of lung disease to identify on xr
- interstitium: linear, discrete (nodules), or combo
- alveoli: filled with air or fluid
- pattern: nodular or diffuse
- timing: acute or chronic
how can you see a pneumothorax on xray
it will be blacker - then the lung
what is the most frequent sign of mediastinal disease
widening
what is a straight line seen in the mediastinum represent
hiatal hernia
how can you see CHF on an xray
- cardiac changes
- left border of the heart moves laterally
- cardiac apex moves anterolateral
- cardiothoracic ratio > 0.50 - Kerley B lines
- Alveolar edema
- vasculature: lower lobe vessels larger than upper
when would you decide to perform a CTA
when you have a positive pretest probability - NPV 99 %
describe Well’s criteria
3 point - suspected DVT
1.5 points - tachy, recent sx, previous PE/ DVT
1 point - hemoptysis or malignancy
VQ perfusion scan problems
very difficult to read therefore alot of error
what is used for pretest probability of VQ scans
PIODPED II - high probability, nondiagnostic, low probability
