CXR Interpretation Flashcards
Give the overall structure of a CXR interpretation
- Confirm patient details - name, DOB & unique identifier
- Confirm date & time of film
- Compare with previous imaging
- Rotation
- Inspiration
- Penetration
- Exposure
- Airway
- Breathing
- Cardiac
- Diaphragm
- Everything else
What does rotation in CXR refer to?
refers to poor positioning – the patient is turned and not straight which can make interpretation difficult
How can you assess rotation in a CXR?
- Medial aspect of each clavicle should be equidistance from the spinous processes
- Spinous processes should be vertically orientated against the vertebral bodies
In this CXR, which way is the patient rotated?
How do you know?
Patient is rotated to the left
Anterior structures move the same direction as rotation → the clavicle/spinous process width is increased on the side to which the patient is rotated
Should CXRs be taken during inspiration or expiration? Why?
Inspiration
Deeper inspirations show more lung and result in better overall images with less haziness at the lung bases and less enlargement of the heart and mediastinum.
How can you tell if a CXR has been taken during a good inspiration?
Count the anterior ribs on the right → 6 anterior ribs should be visible above the right hemidiaphragm
Anteriorly, which rib should intersect the diaphragm and where?
6th rib at the mid-clavicular level
How can you assess for hyperexpansion on a CXR?
- Count ribs → >7th anterior rib intersecting the diaphragm at the mid-clavicular line
- Check for flattening of hemidiaphragms
What is lung hyperexpansion a sign of?
obstructive airway disease
What is the standard CXR projection?
PA
When would a PA not be possible?
if patient is too unwell to stand
Why are PA’s preferred over APs?
PA films are of higher quality and more accurately assess heart size
How can the scapulae determine if a CXR is PA or AP?
PA → scapulae retracted laterally so do not overlap lungs
AP → scapulae not retracted laterally so remain projected over the lung
Scapulae in AP CXR:
Scapulae in PA CXR:
How does the heart size differ in AP? Why?
Heart size exaggerated as it is an anterior structure
Magnification exaggerated further by shorter distance between x-ray source and patient
Can you diagnose cardiomegaly on an AP CXR?
No - BUT if heart size is normal on AP, you can say it’s not enlarged
Why are scapulae laterally rotated in PA CXR?
Patient places hands around side of detector plate, or stands with hands on hips
What is the normal cardio-thoracic ratio in a PA CXR?
<0.5/50%
What does xray penetration mean?
Penetration is the degree to which x-rays have passed through the body.
In a good CXR, what 2 criteria can tell if penetration is adequate?
- The left hemidiaphragm should be visible to the edge of the spine
- The vertebrae should be visible behind the heart
Underpenetration affects the differentiation of which density structures?
Under-penetration results from not enough x-rays passing through to allowing differentiation of dense structures → spine and mediastinum appear white
How can you tell this CXR is underpenetrated?
- Mediastinum and spine appear white
- Left hemidiaphragm not visible to edge of spine
- Vertebrae behind the heart barely visible
- Lug tissue behind heart cannot be assessed
Over penetration affects the differentiation of which density structures?
Prevents differentiation of low-density structures → lung fields appear black
What aspects are involved when assessing the ‘airway’ in a CXR interpretation
- Trachea
- Carina
- Bronchi
- Hilar structures
What are you inspecting the trachea for in ‘airway’?
Deviation
How should a normal trachea appear?
Normal → Trachea normally centrally located or deviating very slightly to the left
What is a true vs apparent tracheal deviation?
True → pushing/pulling by pathology
Apparent → rotation of patient can give appearance of apparent tracheal deviation (inspect clavicles to rule out)
Give 2 causes of a true tracheal deviation caused by the pushing of the trachea
- Large pleural effusion
- Tension pneumothorax
Give a cause of a true tracheal deviation caused by the pulling of the trachea
Consolidation with associated lobar collapse
Diagnosis:
Large pleural effusion with tracheal deviation
What is the carina?
The carina is cartilage situated at the point where the trachea divides into the L and R bronchus.
On appropriately exposed CXR, this division should be clearly visible.
Why is the carina an important landmark in NG tube placement?
NG tube should bisect the carina if it is correctly placed in the GI tract
How does the R and L main bronchus differ?
Which is more likely for inhaled foreign objects to become lodged in?
R main bronchus is wider, shorter, and more vertical than the L main bronchus
Right
What does the hilum of each lung consist of?
The main pulmonary vasculature and the major bronchi (also a collection of lymph nodes)
Which hilum is often positioned slightly higher?
The left is often positioned slightly higher than the right