Thoracic Imaging: Chest X-Rays Flashcards
when are some instances when you may order a chest x-ray?
(indications)
- acute respiratory/cardiac disease
- major chest trauma
- hemoptysis
- dyspnea
- post tube/line insertion
- suspected mass, LAN, metastisis
- suspected PE, Pulmonary edema, CHF, PNA, Pleural effusion, PTX, TB
when would you NOT get a chest x-ray
- routine following pneumonia
- no clinical change in ICU pts.
- minor chest trauma (rib fracture)
- URTI
- lung cancer screening (get CT)
- acute asthma (isnt going to help clinical decision making)
what are the 4 parts of adequacy for a chest x -ray
- penetration
- rotation
- magnificaion
- angulation
what is penitration of an x-ray ?
how do you determine if its proper penitration on an x ray ?
what is over and under penitration?
penitration:if the appropriate amoutn of radiation was used to caputre the image
you should be able to see the throacic spines through the heart shadow
over-penitration: the lung markers will be decreased or absent (look too black)
under-penitrated: unable to see the sping through the heart (too light)
what is rotation of the x ray?
how is it determined?
rotation: the film should be perpendicular to the pt.
check that the medial ends of the clavical are centered around the spinous processes of the vertebrae
slight rotation may be ok depending on the pt. and the study
but tii much can alter the size and visability of specific things in the thoracic cavity
what is angulation of the x-ray?
how do yu determine if there is proper angulation?
think rib counting! should see the 3rd rib intersect with the clavicle
sometimes the pt. is just kyphotic (curved) or slumped in bed!!
what is adequate inspiration for an x-ray?
what can you do to determine adequate inspiration?
why might there be poor inspiration?
poor inspiration: the lungs will be compressed and the lung markings will be crowded (take a deep breath before!)
- can be due to LOC, poor effort, mechanical restriction of the lungs (disease, pregnancy, obeset, laying in bed)
count the ribs on image – should see about 7-10
what is magnification on x-ray?
what directions (AP, PA) will produce bigger or smaller shadow
magnification: the size of the heart will change depedning on which way the x-ray was taken
AP: anterior-posterior (the emitter is in the anterior – heart is closer) therefore the shadow of the heart will appear larger
PA: posterior-anterior (the emitter is in the back commonly how its done standing)
the heart shadow will be smaller
how is cardiomegaly identifed on xray?
- AP? PA?
- PA film: if the heart covers > 50% of the thoracic rib cavity = cardiomegaly
- AP film: if the left heart border is touching the left chest wall = cardiomegaly
not diagnostic but signs pointing towards
how will atelectasis appear on imaging?
Atelectasis: a collapsed lung (or lobe of the lung!! (not due to a buildup of air in the pleural cavitiy– but a lost of air within the lung itself)
-loss of air inside the lung –> lung will appear white on imaging
-increased densitiy of the lung
- a shift of the mediastium (the bronchi and tracha) towards the side of the atelectasis)
- sail sign the collasped lobe ( LLL)
usually due to an obstruction in the airway (mucus plug, obstruction, tumor, FB)
-inhibition prevents inhaliation but may allow air to escape
How will a pneumothorax present on imaging?
pneumothorax: air in the pleural cavity
- identified as losing the lung vasculature markings in areas where the lung should be
- seeing the “outline” of the lung, visceral pleura not at the full inspiration it should be at (towards the chest wall)
- tension pneumothorax does not require xray since its life threatening –> you will commonly see a shift of the mediastinum away from the side of the pneumo. as the air is creating pressure
what are airspace diseases? what are intersistial diseases? how are they different
airspace disease: a disease of the airways within the lungs – the alveoli
- some disease process takes up the airspace (which should be darker on image) become consolidated
- seen in pneumonia, hemorrhage, pulmonary edema, aspiration (things in the airway!)
interstitial disease: disease of the lung paryenchyma itself (the interstitum, walls of the alveoli or the capillary walls)
- described as infiltrative
- seen in idopathic pulm. fiberosis, scleroderma, bronchogenic carcinoma, sarcoidosis
how will airspace diseases appear on xray? what are some descriptors?
- airspace disease appears “fluffy” or “cloud-like” consolidations on imaging
- there are no sharp borders/hard lines unless it is the edge of a lung lobe, etc.
- air bronchiograms areas where usually the bronchi would not be seen (as the entire lung is mostly black) but when the alveoli are conslidated (look white) the bronchi appear to stick out on imaging
- silhouette sign usually each thing should have its own borders, easily identifiable but a silhouette sign is when two strucutres share a border (like the heart and a tumor)
how will interstital lung diseases appear on xray? what are some descriptors?
- reticular: networks of lines (inflammed connective tissue)
- nodular: assortment of dots
- reticulonoldular: a combo
- will not see airbronchiograms and will not be uniform in appearance
how will a pleural effusion appear on imaging? different reasons for transudative v exudative effusion?
transudative: think fluid overload due to imbalance in osmotic pressure
- CHF, liver dz, renal dz.
exudative: higher in protein – think cancer or infection
- malignancy
- empyema
- hemothorax
- chylothorax
imaging
- appear with a minuscus shape
- blunted costophrenic angle
- can be loculated – in that fluid gets trapped in pockets between fiberosis septal lines
how will pneumonia appear on x ray?
how is it different from CHF? from atelectasis? from an effusion?
pneumonia is an airspace disease… so we look for signs of airspace dz. on xray
- air bronchiograms & consolidation
CHF v PNA?
- CHF will be bilateral
atelectasis v PNA?
- atelectasis will alwasy be medial as the lung is collapsing in
effusion v PNA?
- effusion will be homogenous throughout the entire thing
PNA can be in one lobe of the lung – need to identify where & can use lateral imaging to help pinpoint
(PNA can also have cavities –some bacteria are prone to)
how will CHF appear on x-ray– patterns of edema
two patterns… becuase its an increase in pressure from the lack of pumping in the heart – fluid!!
- interstitial edema
- alveolar edema
how will interstital edema from CHF present? key radiographic findings
- pleural effusion
- kerley B lines : thickening of the interlobar septum with fluid specifically seen in the BASE of the lung, PERPENDICUAR to pleura and SHORT and THING
- periobronchial cuffing : fluid in the walls of the bronchi make them appear like donuts on imaging in high numbers
- fluid in the fissures of the lungs : fluid in the large fissures of the lungs (large kerly B lines)
how will alveolar edema from CHF present on x ray? key findings
- fluid spills from interstital areas to the airspaces in alveolar edema
- bat-wing distribution of fluid in the hilar region : appear fluffy
non cardiac causes of pulmonary edema? (intersitisal or alveolar)
think fluid
- sepsis
- uremia
- DIC
- smoke inhalition
- near-drowning
- volume overload
- lymph spread of cancer
how does emphysma present on imaging?
- airtrapping disease due to lost elasticity (increased compliance and inability to get air out)
- hyperinflation & flattened diapraghm
Lung Masses & Lung Cancer
- when to worry about cancer on imaging?
- a small singular node = not a worry usually
worry when…
- multiple nodules/masses
- greater than 1 cm
- irregular in shape, borders
- doubling in size in a year
** full body CT or PET can be used if worried about metastisis**
when is x-ray used for tube placement?
where should an ETT be placed?
what about CVC?
NG?
ETT(endotrachial tube): should be 3-5 cm above carina
CVC (Centeral Venous Cath. “central line”): should be 1-2 cm above carina
NG (nasogastric) : should be 10 cm past the esophagogastric junction seen on left where hemidiaphragm and thoracic spine meet
