Equine Diagnostic Imaging Flashcards Preview

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Flashcards in Equine Diagnostic Imaging Deck (30)
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1
Q

Name 5 diagnostic imaging modalities

A
  • Radiography
  • Ultrasonography
  • MRI
  • Computed tomography
  • Nuclear scintigraphy
2
Q

What is kVp?

A

Speed of electrons (energy of photons)

3
Q

What is mA?

A

Number of electrons released

4
Q

What is s?

A

Time

5
Q

What are radiographs?

A
  • Static image of dynamic tissue

- 2-D representation of 3-D object

6
Q

How can you help stop superimposition of structures?

A

Obtain different views

7
Q

What are the 3 phases of film reading/reporting?

A
  1. Recognition phase (Search)
  2. Descriptive Phase (report)
  3. Interpretation Phase (Differential diagnoses)
8
Q

Describe the recognition phase

A
  • Systematic search pattern
  • Which structures are visible?- soft tissue, bone, articulations
  • Abnormal findings
  • Normal findings
  • Normal variations
9
Q

Describe the descriptive phase

A

Categorise according to radiographic (Rὃntgen) signs

10
Q

Describe the radiographic (Rὃntgen) signs

A
  • Size: Objective measurements or subjectively compared with other normal structures
  • Shape
  • Position
  • Number
  • Margination: well defined, poorly defined, sharp or blunt margins etc.
  • Opacity : Gas, Fat, Fluid/Soft tissue, Mineral, Metal
11
Q

Describe the Interpretation Phase (Differential diagnoses)

A
  • History
  • Signalment
  • Clinical signs
  • Diagnostic tests
12
Q

What factors make up film quality?

A
  • Positioning
  • Collimation
  • Contrast
  • Exposure
  • Labelling
  • Artefacts
    Pink Camels Collect Extra Large Apples
13
Q

Describe the features of ultrasonography

A

• Non-invasive imaging modality
• Sound wave produced by piezoelectric crystal:
- Reflected from tissue interface
- The ultrasound probe receives the waves back and displays it as a pictorial image on a digital screen
- Degree of reflection determined by tissue density
• No ionising radiation

14
Q

The US wave can either be?

A

Reflected
Absorbed
Scattered

15
Q

Attenuation is increased with?

A

Depth

16
Q

How does air appear on ultrasound?

A

White

17
Q

How can air affect an image?

A

Air appears white on an ultrasound image and can affect the image seen – ultrasound gel used to stop this

18
Q

How is contact of the ultrasound improved?

A
  • Clip and clean skin
  • Ultrasound gel
  • Standoff
  • Alcohol: not clipped
19
Q

Describe the ultrasound examination technique?

A
Systematic
- Proximal to distal
- Transverse and Longitudinal
Comparison 
- To opposite “normal” limb/structure
- To “normal” scan of single structure (liver, kidney, heart)
20
Q

How does bone affect ultrasound?

A

Bone is a reflector of ultrasound waves so cannot see any structures below this

21
Q

How are lesions describes on ultrasound?

A
  • Size: actual size or CSA %
  • Shape, Position, Number
  • Margination: Fibre alignment
  • Echogenicity
  • Assess in transverse and longitudinal images
22
Q

What is the function of gamma scintigraphy

A

Basis of the machine is to try and detect areas of actively turning over bone

23
Q

What are the 3 phases of gamma scintigraphy scanning?

A
Phase I – blood pool:
- Rarely used in equine
- immediate
Phase II – soft tissue:
- 2-15 minutes
- Diffusion to extracellular fluid
Phase III – bone:
- 2-3 hours
- Bound to HAP
24
Q

Increased binding on gamma scintigraphy occurs in areas of…?

A
  • Inflammation
  • Bone repair/remodelling
  • Osteomyelitis
  • Neoplasia
25
Q

Describe the main features of radiation safety

A
  • Minimise contact with radioactive horse
  • Wear gloves when handling
  • Contain urine and faeces
  • Monitor radiation exposure
26
Q

What are the advantages and disadvantages of gamma scintigraphy?

A
  • Useful addition to the diagnostic work up
  • Not to be used as a replacement for nerve blocks or thorough clinical examination.
  • Conditions that have primarily soft tissue pathology will not be identified
  • Sensitive but not very specific
  • Use in combination with other imaging modalities and diagnostic analgesia
27
Q

What does MRI stand for?

A

Magnetic resonance imaging

28
Q

What are the advantages of MRI?

A
  • Detail +++
  • Diagnosis: specific and sensitive
  • Treatment options: directed treatment versus lesions
  • Prognosis: single vs multiple lesions
29
Q

What are the limitations of MRI?

A
  • Multiple findings: significance of each/primary finding
  • Aging of lesions?
  • Prognosis?
  • What will happen to the lesion with time?
  • Will the lesion resolve or not?
30
Q

Describe equine CT

A
  • Standing or GA
  • Standing CT – only really practical for heads and some parts of the cervical spine
  • GA – distal limbs and head and cervical spine
  • As with MRI examinations, CT examination of other parts of the body is not really possible