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
- 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
Pneumothorax?
- 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 ____
RML
Loss of right hemidiaphragm indicates that the infiltrate is in the ___
RLL
Loss of L heart border indicates infiltrate in the ____
LUL (lingula)
Loss of L hemidiaphragm indicates infiltrate in ___
LLL
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
abcde
- 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?
No
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
What is an azygos lobe?
-
Azygos lobe- normal variant seen in RUL
- See fine curved line extending from right lung apex downward to mediastinum
- Made by azygous vein migrating inferiorly from lung apex while trapping some of the lung medially
- See fine curved line extending from right lung apex downward to mediastinum
What to look for at diaphragms in CXR?
- Dome-shaped
- Right diaphragm usually higher than left (d/t heart pushing down on the left side)
- Blunting→ pleural fluid
- Lateral views- can tell which side looking at if you see gas bubble (left side- stomach)
Boney structures to look out for on CXR?
- Look for symmetry of ribs at same level
- Older pts- significant calcification of anterior ends of ribs can occur (normal)
- Rib fracture- should alert you to flail chest, pneumothorax, hemothorax, pulm contusion, cardiovascular injury, pot injury to organs
- Views that could be skewed but normal d/t bones:
-
Pectus deformity- cause apparent cardiomegaly
- (sternum depressed and squashed heart against the spine, making the heart look wider than normal on PA view)
- Rhomboid fossa- scalloped appearance from portions of clavicle (check if bilateral- normal)
-
Pectus deformity- cause apparent cardiomegaly
What is ARDS?
- Uncertain etiology
- Damage results from leakage of fluid from alveolar capillary bed
- pts in ICU for several days/intubated
- may occur in postop pts w/ normal pulm fx who in the immediate postop phase had tachypnea, anxiety, and breathing fatigue develop
- systemic nonpulm infections also can damage pulm parenchyma and produce ARDS
- diffuse or patchy alveolar infiltrates throughout both lungs
- exclusion of concurrent bacterial pneumonia or CHF
- dx best made on clinical grounds
- if alveolar infiltrate changes rapidly (w/in several hrs-1 day) → CHF or fluid overload
Difference b/w ARDS and CHF?
-
ARDS:
- Kerley B lines should not be present
- Pleural effusions occur late
- Heart size normal
- Alveolar infiltrates extend to lung periphery
-
CHF:
- Kerley B lines
- Pleural effusions
- Increased heart size
- Perihilar or basilar infiltrates
What are some causes of hilar enlargement?
- Enlarged pulmonary arteries (pulm HTN)
-
Lymphadenopathy
- Lymphomas (Hodgkin’s disease) → visualized as large anterior medialstinal mass or hilar adenopathy.
- If lymphomatous mass is large and up against aorta → mass can be mistaken for aortic aneurysm
- Hilar adenopathy often difficult to distinguish from enlarged central pulm arteries
- Extensive adenopathy can be recognized by multiple lumps/bumps rather than single one
- Single one→ (expect from pulm art)
- Adenopathy may fill normal concavity between left main pulm art and aortic arch
- Any questions remain → CT scan
- Extensive adenopathy can be recognized by multiple lumps/bumps rather than single one
-
Lung neoplasm
- If cause unknown/effective therapy exists→ contrast chest CT scan indicated for further investigation
What do you look for on CXR with pneumothorax?
- Upright- look at R and L hemithoraces
- Look adjacent to ribs (no lung BV seen)
- very thin white line (visceral pleura) and parietal pleura separated by air! (get inspiratory and expiratory film) (may be easier to see on expiratory film)
- Look adjacent to ribs (no lung BV seen)
- How much lung collapses is fx of how much air can get in pleural space
- Pts w/ adhesive pleural changes (prev. inflame disease/scarring) or diffuse lung dx→ complete collapse of lung is not possible
What is a hydropneumothorax?
-
Hydropneumothorax- Pneumos occurring with pleural fluid present
- Characteristic- straight horizontal line as result of air-fluid level in pleural space, straight line extends to chest wall
Things to recognize as a skin flap instead of a pneumo?
- Recognize 3 things: often extends above lung apex into supraclavicular soft tissues, increasing density or whiteness as you look from hilium toward periphery, skin fold line is relatively straight (pleural line follows curve or inner aspect of chest wall)
How much air in pleural space do you need before you see pneumothorax on supine CXR?
Need 500 ml of air in pleural space
- Look out for deep sulcus sign on supine AP CXR
- Extremely sharp/deep costophrenic angles can be sign of pneumothorax
- have pt sit upright, and take another CXR, normally will see apical pneumothorax
What is good to keep in mind with pts with adhesive pleural changes/inflammatory disease/scarring in lungs?
Air does not move frely—> loculated pneumothorax
What is pneumomediastinum?
- Air collections vertical are found within the upper portion of mediastinum and lower neck. Lateral view can see air in front or behind trachea
- Result from tracheobronchial tear (posttramatic pt who’s chest tube does not resolve issue)
How are pleural effusions best seen on CXR?
- Best seen on upright x-ray (will be at least 100mL if seen on CXR)
- Blunting* on AP or PA and blunting of posterior costophrenic angle seen on lateral view
- Upright view:
- Increasing basilar density (whiteness) and loss of normal lung-hemidiaphragm notes
What is a subpulmonic pleural effusion?
- hemidiaphragm R side higher than normal, with highest portion of some more lateral than usual
- Normally- highest portion of dome on right hemidiaphragm is midclavicular line or slightly medial to that
- If highest portion lateral→ subpulmonic effusion
What is a loculated pleural effusion
- Loculated pleural effusion- w/in fissure, lenticular or oval (not round) and located in expected position of fissure
What is common cause of left-sided pleural effusions? Right? Bilateral?
- Left sided effusions: pancreatitis
- Right sided: cirrhosis
- Bilateral: cardiogenic (associated w/ cardiomegaly and other s/s of CHF)
