CXR interpretation Flashcards
What patient scenarios might justify a CXR?
- PNA
- Immunocompromised pt
- COPD with acute exacerbation
- Foreign body
- CHF
- Aspiration pneumonia
- Blunt trauma
- Rib fracture
- Lun tumor
- CP
- Suspected pneumothorax
- SOB (severe)
- Hemoptysis
- Pulmonary HTN
- Pulmonary embolism
- Interstitial lung dx
- ICU pt (adm, invasive lines, ETT)
What are some basic tissue densities noted on a CXR?
- Black- air
- Dark gray- SQ tissue, fat
- Light gray- soft tissue
- Muscle, heart, blood vessels, pus, blood, watery stuff
- Off White- bone
- Bright White- metal
- Pacemakers, surgical clips, bullets
What are some limitations of a supine CXR?
- Supine limits full inspiration
- Cephalic push noted→ liver and ABD contents pushing up on lungs/diaphragm
- Small pleural effusion will stay in posterior pleural space and can be missed
- Pneumothorax
- Air would go to anterior portion of chest and may not be able to see it as well
- Be careful interpreting supine films!
What are some differences of AP versus PA CXR?
- AP
- Xray beam entering anterior thorax/exiting posterior thorax
- Pt position- supine
- Detector position- under them, below them, or on back
- Heart size- magnified, accentuated
- Diaphragm- cephalad push
- PA
- Xray beam entering posterior/exiting anterior
- Pt position- upright, sitting
- Detector position- in front of chest
- Heart size- truer to size
- Diaphragm- caudal push
When might an expiration CXR be useful?
- Small pneumothorax
- Expiration will make lung smaller and denser→ makes pneumothorax appear larger
- Lodged foreign body
- “Ball-valve phenomenon”
- On inspiration, air can move past the object, but during expiration, the bronchus gets smaller, and air cannot exit around the object
- The expiration image will show air trapping in affected lung and mediastinal shift toward unaffected side.
What conditions might cause a pneumothorax and what might be seen on the Cxr?
- Pneumothorax- air positioned between visceral and parietal pleura
- Trauma, SCL catheter
- Liver bx
- spontaneous→ bleb rupture
- Mets
- Take with upright film preferred
- Deep sulcus sign present
- If pt supine- air will be anterior portion chest
- Costophrenic angle- air travels and goes to sulcus (deep groove) and push/migrates caudal
- Costophrenic angle looks longer, deeper, more acute
- Costophrenic angle- air travels and goes to sulcus (deep groove) and push/migrates caudal
- If pt supine- air will be anterior portion chest
What is a pleural effusion, some causes, and what will you look for on a CXR?
- Pleural effusion- collection of fluid between the visceral and parietal pleura
- 100 mLs to be detected on upright CXR
- Look for:
- Blunting of costophrenic angles
- CLASSIC place to look in upright position
- Fluid will go down and angle will not be sharp, acute, demarcated
- Increased basilar density (whiteness)
- loss of normal lung- Hemidiaphragm is noted
-
IF SUPINE- see effusion horizontally in posterior pleural space (increased density/whiteness)
- When in doubt→ get decubitus (on their side)
- Blunting of costophrenic angles
- Causes:
- Malignancies
- Pancreatitis (left side)
- Cirrhosis (right side)
- CHF (bilateral)
- PNA
Describe some causes for a mediastinal shift, and which way the shift would be.
- Tension pneumothorax- mediastinum shifted toward UNAFFECTED side
-
Atelectasis- collapse of entire lung segment result in severe volume loss
- See mediastinal shift toward AFFECTED side
- Airway obstruction- mediastinal shift toward UNAFFECTED side
What is overexposure and underexposure on a CXR? What might be easier or harder to see on each exposure?
Overexposure
- Image is dark
-
Easy to see
- Thoracic spine
- Medistinal strucutre
- Clavicles (bone)
- Behind the heart (retrocardiac)
- NG and ETT placement
-
Cannot see
- Pulmonary vessels
- Small nodules
- Fine structures
-
Easy to see
Underexposure
- Image is white
-
Easy to see
- Pulm vasculature (don’t mistake for infiltrate)
-
Cannot see:
- Behind the heart
- Spinal anatomy
- Behind hemidiaphragms
-
Easy to see
What is the silhouette sign?
- Useful in interpreting CXR
- Determine location of abnormality in relation to normal structures
- RML vs RLL
- Loss of right heart border= infiltrate in RML
- Loss of right hemidiaphragm= infiltrate in RLL
- Loss o left heart border= infiltrate in LUL
- Loss of left hemidiaphragm= infiltrate in LLL
What are mediastinal masses and where can certain pathological processes be seen?
Mediastinal mass→ widening or bulge in central soft tissue of the chest
- Anterior (tumors) (4T’s)
- Thymoma
- Thyroid lesions
- Teratoma- germ cell
- T cell lymphoma
- Middle
- Thoracic aorta aneurysms
- Neoplasms
- Adenopathy
- Diaphragmatic hernias
- Posterior
- Neurogenic (90%)
- Neuroblastomas
- Neurofibromas
- Schwannomas
- Ganglioneuromas
What is a systematic approach to analyzing CXR?
- Who
- What (orientation)–> AP, PA, Supine, upright
- When
- Why→ hx and PE important!
- Exposure
- Airway→ trachea dark (air), appears midline
- Bone→ see spinous process, clavicles, appear flat, ribs good
- Cardiac→ see all boarders, see aortic knob, measure how big (no > ½ chest)
- Diaphragm/medistinum- hila composed of pulm arteries and major bronchi, no widening (masses)
- Everything Else- markings all the way out to ⅓ of lung fields, address NG tube, ETT
How can you tell if there is good inspiration or hypinflation on a CXR?
- Good inspiration= hemidiaphragm down to level of posterior 10th/11th rib
- standing–> 10th rib
- sitting/lying–> between 8-10th rib
- Hypoinflation- dome at 7th rib
Why is position important on CXR? What might be affected based on position?
- Magnification
- organ position
- blood flow
- gravitational pull