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Flashcards in CXR intepretation Deck (46)
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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
  • Be careful intepretating supine films


What are some justifications for CXR?

  • 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


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 is PA view? AP?

PA- Xray plate anterior. Shooting from posterior--> anterior

AP- Xray plate posterior. Shooting form anterior--> posterior


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?

  • 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



  • Air positioned betwen the visceral and parietal pleura
    • trauma, SCL venous catheter, liver bx
    • spontaneous (bleb rupture)
    • met tumor
  •  upright best position
  • 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?

  • 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
  • Cuases
    • malignances
    • pancreatitis (left sided)
    • cirrhosis (right sided)
    • CHF (B)
    • pneumonia
  • Upright is preferred position!!


Where are mediastinal shifts in tension pneumo? atelectasis? airway obstruction?

  • Tension pneumo- mediastinum shifted 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 determien the locaiton of an abnormlaity in relation to normal sturcutres
  • RML vs RLL (PNA, masses)


Loss of right heart border inicates the infiltrate is in ____



Loss of right hemidiaphragm indicates that the infiltrate is in the ___



Loss of L heart border indicates infiltrate in the ____

LUL (lingula)


Loss of L hemidiaphragm indicates infiltrate in ___



How big is too big for heart?

Should not be more than 50% of thorax (from most lateral border)


Aspiration PNA?

  • Inhalation of gastric contents
    • following sz, cardiac resus, anesthesia related complication
  • CXR performed immeidately after incidence
  • F/U should b eperformed within 12 hours
    • may take several hours for gastric contents to react with lugn to cause fluid exudate and an alveolar infiltrate


What are some causes of anterior mediastinal masses?

  • thymoma
  • thyroid lesions
  • teratoma (germ cells that have teeh, hair etc.)
  • t-cell lymphoma 

the 4 T's


What are some causes for middle mediastinal masses?

  • Thoracic aortic aneurysm
  • neoplasm
  • adenopathy
  • diaphragmatic hernia


What are some reasons for posterior mediastinal masses?

on lateral view

  • neurogenic (90%)
  • neuroblastomas
  • schwannomas
  • ganglioneuromas


Systematic approach to reading CXR?

  • Who
  • What--> AP, PA, supine, upright
  • When
  • Why (Reason for CXR)--> hx and PE are extremely important
  • Exposure


  • Airway
  • Bone
  • Cardiac
  • Diaphragm
  • Everything else


What makes up the hila?

pulmonary arteries and major bronchi


Which is higher, right or left hila?

Right hila is somewhat lower than left

It should not be at same level or higher


Are lymph nodes normally seen on CXR?



What should the blood vessels look like in lungs?

  • Trace BV back to hila
    • If you don’t see BV near hila- perihilar infiltrate or fluid may be present (CHF)
  • BV- usually clearly seen out to within 2-3 cm of chest wall/outer 1/3 lung
  • Lines located w/in 2 cm of chest wall is abnormal→ edema, fibrosis, metastatic disease
  • Bronchi should only be as thick as fine pencil point