CXR intepretation Flashcards
How are different tissue densities shown on CXR?
- Black- air
- Dark gray- subcutaneous tissue, fat
- light gray- soft tissue (muscle, heart, blood vesels, pus, etc )
- Off white- bone
- bright white- metal (pacemakers, surgical clips, bullets)
What could you note on a supine CXR?
- Supine limits full respiration
- cephalic push is noted (liver and abdominal contents)
- small pleural effusions will layer in posterior pleural space- can easily by missed because they move anterior
- Be careful intepretating supine films
What are some justifications for CXR?
16
- PNA
- copd w/ acute exacerbation
- CHF
- Blunt trauma
- chest pain
- SOB
- pulm HTN
- Interstitial lung dx
- immunosuppressed pt
- foreign body
- aspiraiton pna
- lung tumor
- suspected pneumo
- PE
- hemoptysis
- ICU pt + change in status
What is view like on upright position?
- inspiration is greater
- Domes of hemidiaphragm should be at posterior rib 10
- good inspiration= hemi diagphragm down to level of post 10/11 ribs
- hypoinflation- dome at 7th rib
What factors may be affected by position?
- magnification
- organ position
- blood flow
- gravitational pull
What is AP XR like (xray beam, position, detector, heart size, diaphragm)
- X-ray beam entering anterior, exiting posterior
- pt position= supine (abd contents cephalad)
- detector position= posterior
- heart size= magnified/accentuated
- diaphragm= cephalad
What is PA CXR (xray beam entering/exiting, pt position, detector position, heart size, diaphragm)
- X ray beam entering posterior, exiting anterior
- pt position= upright
- detector position- ant chest
- heart size= true
- diaphragm= caudal
Which view is more preffered? Why?
PA more preferred
Why? Closer to detector, see pneurmo better
true heart size
When can expiration during a CXR be useful?
2
-
Small pneumothorax
- Expiration will make lung smaller and denser, and at same time, will relatively make the pneumothorax appear larger
-
Lodged foreign body
- ball-valve phenomenon
- air can move past the object during inspiration, but during expiration (the bronchus gets smaller) and air cannot exit arund object
- as a result, the expiration image will show air trapping in affected lung with mediastinal shift will occur toward the unaffected side
Pneumothorax?
how to diagnose on x ray
- Air positioned betwen the visceral and parietal pleura
- trauma, SCL venous catheter, liver biopsy
- spontaneous (bleb rupture)
- metastic tumor
- upright best position to see it.
- Where is first place to look? apex
-
deep sulcus sign (seen when supine)- groove
- longer costophrenic angle that gets deeper
- reliable indicator that you have pneumo
Pleural effusion on CXR?
where to look for
causes
- Collection of fluid b/w the visceral and parietal pleura (100mL to be detected on upright)
- Look for
- blunting costophrenic angles
- increased basilar density (whiteness)
- loss of normal lung-hemidiaphragm is noted
- Causes
- malignances
- pancreatitis (left sided)
- cirrhosis (right sided)
- CHF (Bil)
- pneumonia
- Upright is preferred position!!
Where are mediastinal shifts in:
tension pneumo?
atelectasis?
airway obstruction?
- Tension pneumo- mediastinum toward the unaffected side
- Atelectasis- collapse of entire lung segment might result in severe volume loss. Will see mediastinal shift toward affected side
- Airway obstruction- mediastinal shift toward the unaffected side
What is overexposure?
- Image is dark
- easy to see: thoracic spine, clavicles, behind the heart, NG and ETT placement
- cannot see: pulmonary vessels in the periphery, small nodules or fine structures
What is underxposure?
- Image is white
- Easy to see: pulmonary vasculature (don’t mistake for infiltrate)
- cannot see: behind the heart, spinal anatomy or behind hemidiaphragms
What is a silhouette sign?
- Very useful in intepreting CXR
- helps to determine the location of an abnormlality in relation to normal sturcutres
- RML vs RLL (PNA, masses)
Where the silhouette of the heart is obstructed is where the abnormality is.