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Year 4 > SA Imaging > Flashcards

SA Imaging Flashcards

1
Q

Define collimation

A

Restriction of the beam size to the area under investigation. Good collimation limits scatter

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2
Q

Define exposure

A

Amount of radiation used to generate the image
Under= too white
Over= too black

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3
Q

How is a radiograph generated?

A 
Electromagnetic radiation (x-rays) are produced by electrons colliding with a tungsten anode
A beam of x-rays is directed through the anatomy of interest to a digital plate
The beam is attenuated to varying extents by the tissues it passes through -> image on plate
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4
Q

Give the 5 opacities seen on a radiograph

A 
Air (black; most radiolucent)
Fat
Soft tissue/fluid
Bone (mineral)
Metal (white; most radiopaque)
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5
Q

What does opacity of a tissue depend on?

A

Tissue’s atomic number and physical density

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6
Q

How can you differentiate between fluid and soft tissue on a radiograph?

A

Contrast

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7
Q

How are you able to see margins of organs in the abdomen on a radiograph?

A

Surrounding fat

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8
Q

How do you assess a radiograph?

A 
Identify species and view
Is it correctly labelled?
Is it correctly positioned?
Is the centre of the image the area of interest?
Is it collimated correctly?
Is the exposure adequate?
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9
Q

What is ‘mass effect’?

A

The effects of a growing mass that results in secondary pathological effects by pushing on or displacing surrounding tissue

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10
Q

How do cat skulls differ from dog skulls

A

Greater doming on the frontal and nasal bones
Smaller frontal sinuses (may be absent in Persians)
More complete bony orbits
Wider skulls due to wider zygomatic arches

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11
Q

What is ‘mediastinal shift’?

A

Deviation of the mediastinal structures towards one side of the chest cavity
Causes: volume expansion on one side of the thorax, volume loss on one side of the thorax, mediastinal masses, vertebral/chest wall abnormalities

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12
Q 
What is the normal thickness of the following structures:
Stomach wall
Small and large bowel
Duodenum
Jejunum
Large intestine
A 
Stomach wall: 3-5mm
Small and large bowel: 2-3mm
Duodenum: 3-4mm
Jejunum: 2-3mm
Large intestine: <1.5mm
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13
Q

What is the difference between atelectasis and consolidation?

A

Atelectasis: collapse of one or more areas of lung
Consolidation: swelling and hardening of lung tissue due to the presence of fluid in the alveoli and smaller airways

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14
Q

When is atelectasis seen?

A

After surgery- air sacs collapse as a side effect of anaesthesia.
May also be caused by obstruction of airways (mucus plug/ FB/ tumour)
Pneumothorax
Pleural effusion

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15
Q

When is lung consolidation seen?

A

Pneumonia
Pulmonary oedema
Neoplasia

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16
Q

How do you classify a fracture on a radiograph?

A

Open/closed
Which bone/s?
Position: articular/epiphyseal/growth plate/diaphyseal
Fracture line: transverse/oblique/spiral/comminuted/segmental
Degree of displacement
Reconstructable?

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17
Q

What is border effacement?

A

Borders of an organ are lost due to loss of normal contrasting opacity

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18
Q

What is an air bronchogram?

A 
Black bronchi ('trees') within surrounding white alveoli (filled with fluid or inflammatory exudates)
Seen with alveolar patterns
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19
Q

What can cause osteophytes to form in the stifle joint?

A

Rupture of the cranial cruciate ligament

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20
Q

What is spondylosis deformans?

A

Bony spurs along the bottom, sides and upper aspects of the vertebrae of the spinal column
Response to ageing/ injury/ trauma

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21
Q

What is osteochondritis dessicans?

A

Disturbance of normal endochondral ossification
Often due to disruption in blood supply to the bone
Results in excess cartilage at the site -> abnormally thick, weaker regions of cartilage -> cartilage flap

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22
Q

Which dog breeds are most affected by Ostechondritis dessicans?

A

Large breed dogs eg Great Danes, Labradors, Rottweilers

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23
Q

What is an ‘alveolar pattern’ and when does it occur?

What are the radiographic signs?

A

Occurs when air in alveoli is replaced by fluid or cells, or not replaced at all (atelectasis)
Radiographic signs:
-White fluid opacity, varying from faint or fluffy, to solid, complete opacification
-Border effacement
-Lobar sign (only one lobe is affected)
-Air bronchogram (black bronchi against surrounding white alveoli)
-Effaced vessels

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24
Q

What is a ‘lobar sign’?

A

Only one lung lobe affected by an alveolar pattern

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25
Q

How do you differentiate between a DV and VD thoracic radiograph?

A

VD: diaphragm is flat with ‘Mickey Mouse’ ears
DV: diaphragm is rounded. Heart appears rounder and is displaced into left hemithorax. Fundus visible on the left of the radiograph

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26
Q

How could you tell if a thoracic radiograph is right or left lateral?

A

Right lateral:

  • Can’t see caudal vena cava reaching the 2nd crus of the diaphragm
  • 2 crura of diaphragm run parallel to each other
  • Gas accumulation in fundus of stomach (will be in pylorus on LHS)
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27
Q

Which position should you place the patient in if you want to radiograph a mass on the left lung?

A

Right lateral

Will be harder to see in left lateral as the left lung will be collapsed

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28
Q

How big should a normal heart be on a radiograph?

A

2.5-3.5 intercostal spaces wide, 2/3 the height of the thorax

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29
Q

Why should you always take DV views before laterals?

A

To prevent mediastinal shift

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30
Q

Which is the best radiographic view for evaluating the cardiac silhouette and caudal pulmonary vessels?

A

DV

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31
Q

What would you think if you saw mineralisation in the adrenal glands in cats and dogs?

A

Cats: normal
Dogs: suspect adenocarcinoma

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32
Q

What are the Rontgen signs when looking at a radiograph?

A 
Size
Shape inc margins
Number
Opacity
Location/position
Margination
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33
Q

Why is it hard to differentiate between abdominal organs on a radiograph?

A

Fluid in abdomen -> border effacement

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34
Q

What is a ‘bucky’?

A

Used when radiographing thicker things (>10cm), has a grid on to reduce scatter

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35
Q

When taking a lateral radiograph of the abdomen, what should you centre on?
Where should you collimate?
How should you position the legs?

A

Centre on last rib
Collimate from just cranial to xiphisternum, to greater trochanter
Extend FLs cranially and secure with sandbags/rope ties
Extend HLs caudally and secure with sandbags/rope ties
Place foam pad between FLs and HLs so they are parallel to one another
Check sternum to spine height-should be level. If not, place a foam wedge under the sternum or spine to correct (not under ventrla abdomen as can alter how the abdominal contents lies)

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36
Q

When taking a lateral radiograph of the thorax, what should you centre on?
Where should you collimate?
How should you position the legs?

A

Centre on mid thorax/caudal border of scapula for cats and small dogs
Centre on mid thorax/caudal to caudal border of scapula for larger dogs
Collimate to include the thoracic inlet cranially, and the last rib caudally
Extend FLs cranially and secure with sandbags/rope ties
Extend HLs caudally and secure with sandbags/rope ties
Place foam pad between FLs and HLs so they are parallel with each other
Check sternum to spine height, should be level- if not, place foam pad under sternum or spine

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37
Q

How do you position for a VD thoracic radiograph?
What do you centre on?
How should you collimate?

A

Dorsal recumbency, supported by foam wedges/sandbags
Extend FLs cranially and secure with rope ties
HLs can remain neutral
Check for axial rotation
Centre on sternum/caudal border of scapula for cats and small dogs (caudal to caudal border in larger patients)
Collimation: include thoracic inlet cranially and last rib caudally

38
Q

How do you position for a DV thoracic radiograph?
What do you centre on?
How should you collimate?

A

Sternal recumbency
Place head on foam pad
Place sandbag over neck
Partially extend FLs cranially
Palpate spine to ensure it’s straight, scapulae should be equal height
Centre on spine/caudal border of scapula for cats and small dogs (caudal to caudal border for larger patients)
Collimation: include thoracic inlet cranially and last rib caudally

39
Q

How are veins positioned on a radiograph?

A

Ventral and central

40
Q

Give some differentials for free gas in the abdomen on a radiograph

A

GI perforation eg ulcer, sepsis (gas produced by bateria)

41
Q

How big should a kidney be on a radiograph?

A

<2.5 x length of L2 on VD/DV

42
Q

Why may a kidney be enlarged on a radiograph?

A

Acute renal injury, hydronephrosis (eg obstruction, congenital), polycystic kidneys, neoplasia (lymphoma if bilateral, carcinoma if unilateral), peri-renal pseudocyst

43
Q

Give a differential for seeing a small kidney on a radiograph

A

CKD

44
Q

What do you see with a bronchial pattern on a radiograph?

Why does it occur?

A

Caused by thickening and increased prominence of bronchial walls, usually secondary to chronic inflammation.
Radiographic changes:
-Bronchial walls are visible further out in the periphery compared to normal
-‘Tram lines’ (thickened bronchi seen longitudinally as parallel radiopaque lines)
-End-on bronchi (‘donuts’)

45
Q

What is penumbra?

A

Edge shadowing seen on radiographs

46
Q

When would you use high and low frequency US probes?

A

High frequency: superficial structures

Low frequency: deeper structures

47
Q

How do you differentiate between the liver and spleen on US?

A

Liver is hypo-echoic (more black) compared to spleen

48
Q

How do you differentiate between hepatic and portal vessels on US?

A

Portal vessels have white borders (like ‘portholes’), hepatic vessels do not

49
Q

What may you see in a normal bladder of a cat on US?

A

Floating speckles of sediment or fat

50
Q

The trachea naturally runs on which side of the body?

A

Right

51
Q

How wide should the mediastinum be on a radiograph?

A

No more than 2 x width of thoracic vertebrae

If wide with a soft tissue opacity -> mediastinal mass

52
Q

Give some common diseases associated with an alveolar pattern

A 
Pneumonia
Pulmonary oedema (eg L-CHF)
Haemorrhage
Atelectasis
Neoplasia
53
Q

What is an ‘interstitial pattern’ and when does it occur?

What are the radiographic signs?

A

Occurs when there is thickening, fluid or cellular infiltrate into the interstitial space
Radiographic signs:
-Overall increase in hazy, linear opacities
-Vasculature is ‘smudged’ but still visible

54
Q

Give some causes of an interstitial pattern on a radiograph

A 
Geriatric fibrosis (benign, 'old age' change)
Interstitial pulmonary oedema
Haemorrhage
Interstitial pneumonia
Pulmonary fibrosis
Neoplasia
55
Q

Give some causes of a bronchial pattern on a radiograph

A

Chronic bronchitis
Feline asthma
Bronchiectasis (irreversible dilation of bronchi due to very chronic inflammation)
Pulmonary infiltrates with eosinophilia (severe hypersensitivity reaction)

56
Q

When are ‘vascular patterns’ seen on a radiograph?

Where are the vessels visible on lateral and DV/VD views?

A

Present when pulmonary arteries and/or veins increase in prominence.
Causes: heartworm, L-CHF, left-to-right shunt (PDA, VSD)
Lateral: vessels seen best in cranial lobes
DV/VD: vessels seen best in caudal lobes

57
Q

Which lung lobes does aspiration pneumonia tend to affect?

A

Cranial and right middle

58
Q

Give some causes of megaoesophagus

A 
Hyperthyroid
Myasthenia gravis
Addisons
Idiopathic
Lead toxicity
Mechanical obstruction
Stricture
59
Q

When do growth plates close in cats and dogs?

A

Dogs: 18 months in large/giant breeds,10-12 months in other breeds
Cats: begins at 4 months, usually complete by 7-9 months

60
Q

What do the red and blue colours represent when using Doppler with US?

A

Red: blood flowing towards the probe
Blue: blood flowing away from the probe
(vessel must be running at an angle to the probe therefore angle the probe at least 60 degrees to the vessel)

61
Q

What size needle should you use for US-guided FNA?

A

22G, 1.5” needle

62
Q

When might you use aspiration when taking an US-guided FNA?

A

Lymph nodes, poorly exfoliative masses

63
Q

What should the thickness of the bladder wall be on US?

A

2-3mm

64
Q

Where would transitional cell carcinomas be located within the bladder?

A

Bladder neck

65
Q

How do nasal turbinates differ in appearance from ethmoturbinates?

A

Nasal turbinates are very linear, whereas ethmoturbinates are more tortuous

66
Q

How does the tympanic bulla differ between cats and dogs?

A

Cats: have a septum when separates them into 2 compartments

67
Q

Why may you see dorsal displacement of the trachea on a radiograph?

A

LA enlargement

68
Q

Why may you see ventral displacement of the trachea on a radiograph?

A

Megaoesophagus

69
Q

What might you suspect if you see thickening of the gallbladder wall on US?

A

Start of cholestasis

70
Q

How does the location of gas within the stomach vary with radiographic positioning?

A

RL: gas is located within the body and fundus
LL: gas is located within the pyloric antrum
VD: gas is located within the centre of the stomach
DV: gas is located mainly at the body and fundus, with a small amount at the pyloric antrum

71
Q

How thick should the stomach wall be on US?

A

3-5mm

72
Q

Is mucosa and muscularis hypo- or hyper-echoic on US?

What about submucosa and serosa?

A

Mucosa and muscularis: hypoechoic (more black)

Submucosa and serosa: hyperechoic (more white)

73
Q

What is the normal diameter of the intestines on a radiograph in cats and dogs?

A

Dogs: <1.6 x depth of L5
Cats: 12mm

74
Q

What is functional ileus?

How does it look on a radiograph?

A

Absent peristalsis with no mechanical obstruction

Appears as uniform intestinal dilation, mostly filled with gas

75
Q

What should the diameter of the colon be on a radiograph?

A

<1.5 x length of L7

76
Q

How thick should the wall of the large intestine be on US in dogs and cats?

A

Dogs: 2-3mm
Cats: 1.5-2mm

77
Q

How would you identify megacolon on a radiograph?

A

Partial/generalised enlargement of the colon

Large amount of faecal material is usually present in affected areas

78
Q

Give some causes of megacolon

A

Idiopathic
Neurologic disease
Chronic constipation
Chronic inflammation

79
Q

Give some differentials for pneumoperitoneum (free gas in the peritoneal space)

A

Penetrating trauma
Rupture of a hollow viscus
Iatrogenic (eg secondary to laparotomy)

80
Q

Are lymph nodes visible radiographically?

A

NO, unless enlarged or mineralized

81
Q

How do we assess liver size on a radiograph?

A

By evaluating position of gastric axis on a lateral radiograph (normal= somewhere between parallel to ribs and perpendicular to spine)

82
Q

How would we identify hepatomegaly on a radiograph?

A

Anticlockwise rotation of the gastric axis

Rounded liver margins

83
Q

Give some differentials for hepatomegaly on a radiograph

A 
Endocrine disease
Hepatic lipidosis (cats)
Neoplasia
Venous congestion
Inflammatory/infectious
Severe nodular hyperplasia
84
Q

How would we identify microhepatica (small liver) on a radiograph?

A

Clockwise rotation of the gastric axis

Decreased distance between stomach and diaphragm

85
Q

What would we suspect as a cause of microhepatica on a radiograph?

A

Vascular shunt

Chronic inflammation

86
Q

How would we identify splenomegaly on a radiograph?

A

Thickened, rounded, blunted margins

Dorsal and caudal displacement of the jejunum

87
Q

Give some differentials for splenomegaly on a radiograph

A 
Inflammation/infection
Hyperplasia
Congestion
Neoplasia
GA/sedation (ACP/Thio)
88
Q

How might we see an adrenal mass on a radiograph?

A

Soft tissue/partially mineralised mass craniomedial to a kidney
May displace kidneys ventrolaterally if large enough

89
Q

How would you identify benign prostatic hypertrophy on a radiograph?

A

Symmetric enlargement with smooth, well-defined margins
Cranial displacement of the bladder
Dorsal displacement of the rectum

90
Q

How would you identify prostatitis on a radiograph?

A

Symmetrical/asymmetrical prostatomegaly

Often ill-defined margins

91
Q

When may you see mineralisation of the prostate?

A

Neoplasia

Year 4 (51 decks)

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