Radiology- chest x-ray Flashcards
Projection
Refers to the direction x-rays travel through the body.
Posteroanterior
Anteroposterior.
PA
Gold standard
sPosteroanterior (PA) viewis the standard frontal chest projection
X-ray beam traverses the patient from posterior to anterior
Performed standing and in full inspiration with the patient hugging the detector to pull the scapulae laterally
Best general radiographic technique to examine thelungs, bony thoracic cavity,mediastinumandgreat vessels
advantages of PA
Technically excellentvisualisationof the mediastinum and lungs, withaccurate assessment of heart size.
disadvantages of PA
Patient must be able to stand erect.
AP
Anteroposterior (AP) erect viewis an alternative frontal projection to the PA projection with the beam traversing the patient from anterior to posterior
Can be performed with the patient sitting up on the bed and even performed outside the radiology department using a mobile x-ray unit
Advantages of AP
More convenient for intubated and sick patients who will not be able to stand for a PA projection
Disadvantages of AP
Mediastinal structures may appear magnified as the heart is further away from the detector, often poorly inspired, more likely to be rotated and to create skin folds, scapulae often cover some of the lungs
RIPE
Rotation
inspiration
position
exposure
Rotation
Find the medial ends of the clavicles
Find the vertebral spinous processes
The spinous processes should lie half way between the medial ends of the clavicle
ROTATION OF THE PATIENT WILL LEAD TO OFF-SETTING OF THE SPINOUS PROCESSES SO THEY LIENEARER ONE CLAVICLE THAN THE OTHER
Rotated to left
heart size exaggerated
Rotated to right
true size of the heart underestimated
Inspiration
Chest X-rays are conventionally acquired in the inspiratory phase of the respiratory cycle. The radiographer asks the patient to, ‘breathe in and hold your breath!’
The diaphragm should be intersected by the 5th to 7th anterior ribs in the mid-clavicular line
WHILE CHECKING FOR ADEQUATE INSPIRATION YOU MAY NOTICE THAT A PATIENT’S LUNGS ARE HYPEREXPANDED (>7TH ANTERIOR RIB INTERSECTING THE DIAPHRAGM AT THE MID-CLAVICULAR LINE)
COPD CXR
More than 7 ribs shown
Barrel chest
Position
Entire lung field visible
Exposure
Penetration is the degree to which X-rays have passed through the body
(A) Overexposure makes it easy to see behind the heart and the regions of the clavicles and thoracic spine, but the pulmonary vessels peripherally are impossible to see.
(B) Underexposure accentuates the pulmonary vascularity, but you cannot see behind the heart or behind the hemidiaphragms.
With modern veiwing systems rarely a problem
ABCDE
Airway
breathing
circulation
diaphragm
everything else
Airway
trachea, carina, bronchi and hilar structures.
Breathing
lungs and pleura.
Cardiac
heart size and borders.
Diaphragm
including assessment of costophrenic angles.
Everything else
mediastinal contours, bones, soft tissues, tubes, valves, pacemakers and review areas.
Trachea
Inspect the trachea for evidence ofdeviation:
The trachea is normally located centrally or deviating very slightly to the right.
If the trachea appears significantly deviated, inspect for anything that could be pushing or pulling the trachea. Make sure to inspect for any paratracheal masses and/or lymphadenopathy.
true tracheal- pushing of the trachea
large pleural effusion or tension pneumothorax
true tracheal- pulling the trachea
consolidation with associated lobar collapse
apparent tracheal deviation
rotation of patient
Carina and Bronchi
Theright main bronchusis generallywider,shorterandmoreverticalthan theleftmainbronchus. As a result of this difference in size and orientation, it is more common forinhaledforeignobjectsto become lodged in therightmainbronchus.
Carina
Thecarinais cartilage situated at the point at which thetracheadividesintotheleftandrightmainbronchus.
Hilar structres
Thehilarconsist of themainpulmonaryvasculatureand themajorbronchi.
Each hilar also has a collection oflymphnodeswhicharen’t usually visiblein healthy individuals.
Thelefthilumis often positionedslightlyhigherthan theright, but there is a wide degree of variability between individuals.
Thehilarare usually thesamesize, soasymmetryshould raise suspicion ofpathology.
hilar enlagement
bilateral- sarcoidosis
unilateral- underlying malignancies
abnormal hilar position
pushed- enlarging soft tissue mass
pulled- lobar collapse
Breathing
Inspectthelungsforabnormalities:
When interpreting a chest X-ray you should divide each of the lungs into three zones, each occupying one-third of the height of the lung.
Inspect the lung zones ensuring that lung markings are present throughout.
Increased opacification in a given area of a lung field may indicate pathology (e.g. consolidation/malignant lesion).
The complete absence of lung markings should raise suspicion of a pneumothorax.
breathing Plura
Inspectthepleuraforabnormalities:
The pleura are not usually visible in healthy individuals.If the pleura are visible it indicates the presence of pleural thickening which is typically associated with mesothelioma.
Inspect the borders of each lung to ensure lung markings extend all the way to the edges of the lung fields (the absence of lung markings is suggestive of pneumothorax).
cardiac- heart size
In a healthy individual, theheartshouldoccupy no more than 50% of the thoracic width(e.g. a cardiothoracic ratio of less than 0.5).
This rule only applies toPAchest X-rays(as AP films exaggerate heart size), so you should not draw any conclusions about heart size from an AP film.
Cardiomegalyis said to be present if theheart occupies more than 50% of the thoracic width on a PA chest X-ray. Cardiomegaly can develop for a wide variety of reasons including valvular heart disease, cardiomyopathy, pulmonary hypertension and pericardial effusion.
cardiac- heart borders
Inspect theborders of the heartwhich should be well defined in healthy individuals:
The right atrium makes up most of the right heart border.
The left ventricle makes up most of the left heart border.
Theheart bordersmay becomedifficult to distinguishfrom thelungfieldsas a result of pathology whichincreases the opacity ofoverlying lung tissue:
Reduced definition of the right heart border is typically associated with right middle lobe consolidation.
Reduced definition of the left heart border is typically associated withlingularconsolidation
Diaphragm
Theright hemidiaphragmis, in most cases,higher than the leftin healthy individuals (due to the presence of the liver). The stomach underlies the left hemidiaphragm and is best identified by the gastric bubble located within it.
Thediaphragmshould beindistinguishablefrom theunderlyingliverin healthy individuals on an erect chest X-ray, however, iffreegasis present (often as a result of bowel perforation),air accumulates under the diaphragmcausing it toliftand becomevisibly separate from the liver.
PNEUMOPERITONEUM
PRESENCE OF AIR OR GAS IN THE ABDOMINAL (PERITONEAL) CAVITY
Costophrenic angles
Thecostophrenicanglesare formed from thedome of each hemidiaphragmand thelateralchestwall.
In a healthy individual, the costophrenic angles should beclearly visibleon a normal chest X-ray as a well definedacuteangle.
Loss of this acute angle, sometimes referred to as costophrenic blunting, can indicate the presence offluidorconsolidationin the area.
everything else
Bones
Inspect thevisibleskeletalstructureslooking for abnormalities (e.g. fractures, lytic lesions).
Soft tissues
Inspect thesofttissuesfor obvious abnormalities (e.g. large haematoma).
Tubes, valves and pacemakers
Varioustubesandcableswill be visible asradio-opaque lineson the chest X-ray (e.g. central line, NG tubes,ECG cables).
Artificial heart valvestypically appear asring-shaped structureson a chest X-ray within the region of theheart(e.g. aortic valve replacement).
Pacemakerstypically appear as aradio-opaque disc or ovalin theinfraclavicularregionconnected topacemakerwireswhich are positioned within the heart.
consolidation
infection
