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CVSOH 4 > Diagnostic Imaging > Flashcards

Diagnostic Imaging Flashcards

1
Q

Why are abdominal boundaries assessed on diagnostic imaging?

A

Checking for evidence of rupture or herniation and if boundaries are intact.

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2
Q

What are the differences between imaging cats and dog abdomens?

A
  • Cats have quite prominent areas of falciform and retroperitoneal fat that isn’t so common in a dog
  • In the dog, the spleen lies in a slightly different position to the cat and tail of the spleen usually curls around in the mid-ventral abdomen
  • Spleen less commonly visible in cats
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3
Q

What is indicated by serosal detail in the peritoneal cavity?

A

Good if fat
Poor if young/thin, peritonitis, fluid or neoplasia

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4
Q

How is serosal detail assessed?

A
  • Check body condition – intra-abdominal fat, fat over spinous processes
  • Distension of abdomen – unlikely if very thin animal
  • Free gas – possible GI rupture, previous surgery/trauma
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5
Q

Why do puppies and kittens have little serosal detail?

A

Have rounded bellies but have a general lack of fat and increased proportions of brown fat so little serosal detail.

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6
Q

Where is the spleen visualised on radiographs?

A
  • Head to caudal to stomach on left (see on VD)
  • Tail usually mid ventral abdomen (lateral view)
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7
Q

What does the size of the spleen on diagnostic imaging depend on?

A

Sedation, position, individual/breed variation

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8
Q

Where is the splenic head visualised on radiographs?

A
  • Smooth triangle in left cranial abdomen
  • Caudal to stomach
  • Cranial to left kidney
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9
Q

Why is diffuse splenomegaly hard to assess radiographically?

A

Wide normal range, overlap maximum normal/minimum pathological size, subjective

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10
Q

What is the appearance of diffuse splenomegaly?

A
  • Rounded edges
  • Displacement of other viscera
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11
Q

What is the appearance of splenic masses?

A
  • Generally quite visible radiographically
  • Small intestine displaced caudally or dorsally
  • Very vascular so may bleed causing free fluid and so poor detail
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12
Q

What is the appearance of the liver on radiogrpahs?

A
  • Roughly triangular in shape
  • Soft tissue opacity
  • Smooth distinct margins
  • Ventral lobe – not too rounded, approximately at level of costal arch
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13
Q

How is the gastric axis used to assess liver size?

A

Normal is perpendicular to spine and parallel to the ribs, breed variation in dogs, so if liver falls between these lines it is likely to be normal

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14
Q

When might the gall bladder be visualised on radiographs?

A

In cats

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15
Q

What are the differential diagnoses of small livers?

A
  • Portosystemic shunt – which may be associated with large kidneys in dogs
  • Cirrhosis
  • Chronic hepatitis
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16
Q

What are the differential diagnoses of large livers?

A
  • Acute hepatitis
  • Endocrine hepatopathy – such as cushing’s
  • Congestion
  • Infiltrative neoplasia
  • Focal mass lesion
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17
Q

What is the appearance of the stomach on radiographs?

A
  • Lies in cranial abdomen
  • Caudal to liver
  • Long axis – parallel to ribs
  • Fluid/gas distribution varies with position
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18
Q

Where is the stomach located on radiographs?

A
  • Hiatal hernia
  • Gastro-oesophageal intussusception
  • Diaphragmatic rupture
  • Dilation vs volvulus
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19
Q

What does content and transit time from a radiograph indicate about the stomach?

A

Contents – radiopaque foreign material?

Transit time of food/liquid – outflow obstruction?

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20
Q

Why are plain radiographs often unrewarding?

A

Wall can’t be delineated from fluid content unless there is rugal calcification

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21
Q

What does a single stricture without subdivision suggest about the stomach?

A

Tells us it is dilation rather than a volvulus

22
Q

What are the measurements for the small intestine on radiographs?

A

Variable diameter loops usually around twice the width of a rib and equal to the depth of a vertebral end plate

23
Q

What are the measurements for dilated small intestine on radiographs?

A

Ratio of width SI to heigh of mid-body of L5 – SI:L5 < 1.4 = very unlikely to be obstructed, SI:L5 > 2.4 = very likely to be obstructed

Ratio of width of largest and smallest loops - <2 very unlikely to be obstructed, >3.4 very likely to be obstructed

24
Q

Why are chronic partial small intestinal obstructions harder to diagnose?

A

As there is some obstruction of width but contents can still past through

25
Q

What are the clinical signs of chronic partial small intestinal obstructions?

A
  • Gravel sign
  • Chronic build up of ingesta over time
  • Contents looks like faeces but not in colon
26
Q

What are the differential diagnoses of chronic partial small intestinal obstructions?

A

Intussusception, foreign body, tumour, stricture

27
Q

Where is the colon located in the abdomen?

A
  • Ascending – right mid/abdomen
  • Transverse – crosses caudal to stomach
  • Descending – left abdomen
  • Rectum – within pelvic canal
28
Q

What are the measurements of the colon in cats and dogs?

A

In dogs, the colonic width should not exceed 3 times that of normal small intestine, the length of the body of L7, >1.5 x is likely to indicate dysfunction

In cats, colonic width - <1.3 x length of L5 suggests normal, >1.5 x length is a good indicator of megacolon

29
Q

What are plain radiographs useful for assessed in the colon?

A

Size (megacolon?), shape, contents, position

30
Q

What are contrast media?

A

Agents that are more or less opaque than surrounding tissue. They delineate organs/cavities within the body

31
Q

What are the purposes of contrast media?

A
  • To see structures not normally visible or poorly visible – ureters, urethra, spinal cord
  • To gain more information about soft tissue structures – bladder, kidneys, GI tract
32
Q

Distinguish positive and negative contrast media?

A

Positive contrast – high atomic number

Negative contrast – low density

33
Q

What are 2 positive contrast media?

A

Barium
Iodine

34
Q

What are the advantages of barium contrast media?

A
  • Used in GI tract
  • Inert, non-toxic
  • Reasonably palatable
  • Cheap
  • Good mucosal detail – liquid barium
  • No osmotic effect
35
Q

What are the advantages of iodine contrast media?

A
  • Water soluble organic iodine containing preparations
  • 2 main groups – ionic, non-ionic
  • Intravenous use
  • Renal excretion
36
Q

What are the disadvantages of non-ionic water soluble iodinated contrast media?

A
  • Slightly more expensive
  • Viscous
  • Side effects may still occur, although rare – anaphylaxis, nephrotoxicity, urticaria, vomiting, pyrexia
37
Q

What are the negative contrast media? What is their appearance?

A

Air
CO2

Black on radiograph

38
Q

What are the advantages of negative contrast media?

A
  • Cheap/free
  • Simple to use
  • Relatively safe
  • Can combine with positive contrast agents – double contrast study
39
Q

What are the disadvantages of negative contrast media?

A
  • Very small risk of air embolism – possible reduced by performing study in left rather than right lateral recumbency
  • Poor mucosal detail
  • Produce less contrast than positive contrast agents
40
Q

What is portovenography used to assess?

A

Portal vein and tributaries

41
Q

What is arthrography used to assess?

A

Joints

42
Q

What is angiography used to assess?

A

Blood vessels

43
Q

What is fistulography used to assess?

A

Sinus tracts

44
Q

What are the indications of barium swallow?

A

Dysphagia
Regurgitation
Suspected rupture
Liquid barium and/or barium food – iodinated contrast if suspected rupture

45
Q

When is there is a risk of aspiration of barium swallow?

A

If swallowing problem, struggling, respiratory stress, weak

46
Q

What is a barium follow through study?

A
  • Evaluates stomach and small intestine
  • Liquid barium
  • By mouth or stomach tube
  • Radiographs taken immediately and then at intervals depending on transit time
  • Final images at 24 hours or when all barium in colon
47
Q

What are the indications for barium GI tract studies?

A
  • Vomiting – persistent, recurrent, haematemesis
  • Palpable mass
  • Abnormality suggested by survey films
48
Q

What are the complications of barium GI tract studies?

A

Constipation – rare

Aspiration – if given by mouth

49
Q

What are barium enemas?

A
  • Evaluates the large intestine
  • Need to do a full enema before hand
  • Liquid barium infused into rectum post enema – can follow with air (double contrast)
  • Messy and difficult to interpret
  • Ultrasound can be used to assess colonic wall
  • Technique superseded by ultrasound and colonoscopy – could modify to identify colon with small volume contrast if unclear on plain radiograph
50
Q

What are the minimal complications of barium enemas?

A

Leakage, rarely over-inflation with air causes rupture

CVSOH 4 (13 decks)

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