IMAGING - Thoracic Ultrasound Flashcards
How should a normal lung appear on ultrasound?
A normal lung is gas filled and thus will have parallel reverberation (A lines) which move with respiration. Furthermore, the ribs will cast a strong shadow over the reverberation
How should a normal pleural appear on ultrasound?
A normal pleura should appear as a smooth hyperechoic line which glides with respiration
How does a ‘wet’ lung appear on ultrasound?
A ‘wet’ lung has echogenic artifacts extending from the pleural line, known as B lines
How many B lines would be considered normal in a dog?
Up to two B lines
What are the key signs of lung consolidation on ultrasound?
Normal lung parenchyma is gas filled which will result in reverberation lines, preventing the assessment of the normal lung architecture. However, when there is lung consolidation, the air is replaced by soft tissue/fluid, resulting in the lung appearing homogenously echogenic with visible pulmonary vessels - the lung will resemble the liver. Furthermore, lung consolidation is associated with the ‘shred’ sign
What is the ‘shred’ sign on ultrasound?
The ‘shred’ sign is a sign of lung consolidation. The lung with appear hypoechoic, accompanied by an irregular border in contact with normal, aerated lung
What is the costal ‘step’ sign on ultrasound?
The costal ‘step’ sign on ultrasound is an irregular pleural line which is indicative of thoracic wall injury (i.e rib fractures)
How do transudate pleural effusions appear on ultrasound?
Transudate pleural effusions appear as anechoic on ultrasound
How do modified transudate pleural effusions appear on ultrasound?
Modified transudate pleural effusions appear as hypoechoic on ultrasound
How do exudate pleural effusions appear on ultrasound?
Exudate pleural effusions appear as hyperechoic on ultrasound
How do you differentiate between a pleural and pericardial effusion?
To differentiate between a pleural and pericardial effusion, assess the pericardium. The pericardium is represented by a hyperechoic line around the myocardium, if there is no seperation between the pericardium and myocardium, then it is not a pericardial effusion
When is ultrasound the most useful when it comes to assessing thoracic masses?
Ultrasound is particularly useful if the mass is located in close contact with the thoracic wall and if they have already been identified using radiography. Ultrasound can also be used to guide fine needle aspirates (FNAs) of the mass to avoid accidentally hitting large vessels and the heart
When is colour flow doppler useful when assessing thoracic masses?
Colour flow doppler allows for the assessment of blood flow within the mass
What are the two most common locations for cardiac masses?
Heart base
Right atrium
How should your patient be positioned for echocardiography?
The patient should be positioned in right lateral recumbency and the probe should be placed over the right beat on the right side of the chest
What is the conventional orientation for the short axis views of the heart?
For the short axis views, the left atrium will be on the left side of the screen
How should the ultrasound probe be orientated for short axis views of the heart?
For short axis views, the probe marker should be orientated towards the cranial end of the patient
Which short axis view of the heart is this?
Short axis view of the left ventricle
Identify the structures on this short axis view of the left ventricle
Which short axis view of the heart is this?
Short axis view of the mitral valve
Identify the structures on this short axis view of the mitral valve
Which short axis view of the heart is this?
Short axis view of the heart base
Identify the structures on this short axis view of the heart base
What is the conventional orientation for the long axis views of the heart?
For long axis views, the apex of the heart will be on the left side of the screen
How should the ultrasound probe be orientated for long axis views of the heart?
For long axis views of the heart, the probe marker should be orientated towards the operator
Which long axis view of the heart is this?
Long axis 4 chamber view
Identify the structures on this long axis 4 chamber view
Which long axis view of the heart is this?
Long axis 5 chamber view
Identify the structures on this long axis 5 chamber view
Which view is used to assess left atrial/aortic ratio?
Short axis view of the heart base
What should the normal left atrial/aortic ratio be in a dog?
Less than 1.7
What should the normal left atrial/aortic ratio be in a cat?
1 to 1.2
Which view is used to assess left atrial size?
Long axis 4 chamber view
What should the normal atrial size be on a long axis 4 chamber view in a dog?
10 to 15mm
What should the normal atrial size be on a long axis 4 chamber view in a cat?
14mm
What can be used to assess left ventricular contractility on B mode?
Ejection fraction
What can be used to assess cardiac function on M mode?
Fractional shortening
What is the normal fractional shortening reference range?
33 to 46%
However can be down to 26% in very fit dogs
What is E-point to septal separation (EPSS)?
What is the normal E-point to septal separation (EPSS) value in a healthy animal?
The E-point to septal separation (EPSS) value should be no more than 7mm in a healthy animal
What is indicated by a E-point to septal separation (EPSS) value above 7mm?
Indicative of left ventricular volume overload
What does blue represent on colour flow doppler?
Blue represents blood moving away from the ultrasound probe
What does red represent on colour flow doppler?
Red represents blood moving towards the ultrasound probe
What does green represent on colour flow doppler?
Green represents turbulent blood flow
What is pulse-wave doppler?
Pulse wave doppler uses short burst of ultrasound waves to measure the velocity of blood flow at a specific point. This technique allows for the precise measurement of blood flow in a specific area with can distinguish between laminar and turbulent blood flow, however it has a limitation which restricts the maximum measurable velocity, if the blood flow exceeds this maximum, this can cause the blood flow to appear to be in the opposite direction
What is continuous wave doppler?
Continuous wave doppler continuously emits ultrasound waves allowing for the measurement of higher velocities, which is especially useful in assessing high-velocity blood flow, such as in cases of stenosis. However, continuous wave doppler does not provide information on the exact location of the flow and cannot distinguish between laminar and turbulent blood flow, as it measures the average velocity along the entire path of the ultrasound beam
