Ultrasound examination Flashcards
What are key considerations for ultrasound positioning in different species?
Can examine large animals in standing position
Equine stocks
- Rectal exam – consider height of rear door
- Limb exam – ensure access & operator safety
Farm animal stall
Small animals may lie in recumbency
Consider need for analgesia, sedation or anaesthesia
Pressing on tendon with injury = horse might not stand still
Drugs may affect organ perfusion & thus appearance
How do you ensure optimal image quality in ultrasound exams?
Reduce ambient light (dark room improves visibility)
Clip hair over area of interest
Clean skin (remove dirt & oils using alcohol)
Apply ultrasound gel for proper sound conduction
Ensure full transducer-to-skin contact
What kind of transducer is this?
Linear
What kind of transducer is this?
Curved
Describe linear transducers
Fire multiple lines of sound that are parallel to each other so rectangular beam is created
Requires full contact along surface of transducer to get full cross sectional image
Describe curved transducers
Fire multiple lines of sound that diverge from each other so that triangular beam is created
Requires only small contact area & as beam diverges a large cross section is achieved within body
- good for looking between ribs
What is a standoff, and when should you use one?
standoff moves superficial structures away from near-field noise
Placed between transducer & skin
Commonly used in:
- Equine tendon imaging
- Ophthalmic (eye) ultrasound (gel blob as a standoff)
Allow better visualisation of superficial tissues
How do you choose the right ultrasound frequency?
Higher frequency = Better resolution, but poor depth
Lower frequency = Better depth, but lower resolution
Examples:
- Eye scan: 10 MHz (high resolution, shallow depth)
- Sheep pregnancy diagnosis: 3 MHz (low resolution, deep penetration)
How is transducer orientation standardised for ultrasound imaging?
Notch on transducer marks leading edge of beam
Conventions:
- Longitudinal/Dorsal views → Notch points cranially
- Transverse views → Notch points to the right
Screen display conventions:
- Cranial → Left side of screen
- Right side of body → Left side of screen
- Limb exams → Proximal is left
- Cardiology (heart scans) → Opposite orientation
What are key principles of a systematic ultrasound exam?
Use standard imaging views
Scan in at least two planes
Adjust positioning if needed (e.g., gas interference in the gut)
Understand knobology (machine settings) to optimise images
Recognise artifacts & compare to normal anatomy
Store images for medical records & review
Why is selecting the correct ultrasound preset important?
Ultrasound machines start with pre-set settings (e.g., cardiac, abdominal, superficial)
Using wrong preset can result in poor image quality
Always enter patient details & confirm preset before scanning
What should be adjusted before placing the transducer on the animal?
- Select depth of penetration (may be labeled as magnification or arrows in/out)
- Set overall gain & power to mid/low levels
- Ensure correct transducer type & frequency are selected
- Turn down ambient lighting for better visibility
What should be adjusted after placing the transducer on the animal?
- Adjust depth of penetration so organ fills screen
- adjust focal zone to middle of organ
- adjust overall gain & power so picture quality is good
Describe these gains
What does gain adjustment do, and how do you set it correctly?
Controls brightness of image
Too low = Image too dark, loss of detail
Too high = Image too bright, loss of contrast
Optimal = Balanced brightness with clear echotexture
What is Time Gain Compensation (TGC) and why is it important?
Sound weakens (attenuates) as it penetrates deeper → deeper tissues may appear too dark
TGC allows separate gain adjustment at different depths to ensure uniform echotexture
What are the five key transducer movements to optimise an image?
Sliding (move forward/backward, left/right)
Angling (tilt transducer up/down, side to side)
Rotating (twist transducer for different angles)
Imaging in different planes (longitudinal, transverse, oblique)
Maintaining correct orientation (leading edge should always be known)
What does “knobology” mean in ultrasound scanning?
Adjusting settings dynamically during exam to optimise image quality
Key adjustments:
- Frequency
- Depth
- Focal depth
- TGC (not typically adjusted during scan)
How do you correctly capture and store ultrasound images?
Press Freeze to capture still image
Use tracker ball to scroll back through previous frames if timing is missed
Label image (e.g. left/right, orientation)
Press “Store” or “Print” to save image
If stored while live scanning → short video clip is recorded
What are these arrows pointing at?
- depth of penetration
2/3. gain and power settings
What is this arrow pointing at?
adjust focal zone
What is this arrow pointing at?
Time gain compensation
What are these arrows pointing at?
- freeze
- label
- save
