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Y4 SA - Internal medicine > Approach to abdominal imaging and imaging of parenchymal organs > Flashcards

Approach to abdominal imaging and imaging of parenchymal organs Flashcards

1
Q

How is radiography used as an imagine modality for the abdomen, pros and cons

A
  • Good overview
  • Better to assess size and shape
  • Poor at assessing GIT wall changes or internal architecture of organs
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2
Q

How is ultrasound used as an imagine modality for the abdomen, pros and cons

A
  • Excellent to assess internal architecture and luminal spaces (unless gas filled)
  • Operator dependant
  • Poor in presence of extensive gas
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3
Q

Why would we want to image the abdomen?

A

Aid diagnostics
Foreign bodies
Masses
View any abnormalities
Distention/enlargement
Fluid

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4
Q

Which radiography technique is used to avoid scatter and improve contrast resolution?

A

Low kV, high mAs technique

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5
Q

High/long mAs increase susceptibility to…?

A

Motion artefacts

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6
Q

Which radiographic views do you want to take to visualise the abdomen?

A

Right lateral
Ventro-dorsal

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7
Q

When is contrast used?

A
  • Urinary tract studies
  • Less useful in the GIT
  • Essential for abdominal CT
  • Require good preparation and time …and money!
  • Correct contrast medium for the right indication
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8
Q

Describe barium as a contrast medium

A

Used for GI studies only
- If escapes into body cavities: severe granulomatous inflammation, depending on amount: death

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9
Q

Describe iodinated contrast media

A
  • Can be used for GIT, urinary tract, IV and for myelography.
  • Safest: non-ionic and low osmolar iodinated contrast media
  • Anaphylaxis, shock if escapes into body cavities (however of limited duration and considered the best alternative), local irritant, kidney failure for IV
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10
Q

Describe gas/air as a contrast media

A

Limited use, can cause fatal air embolism on rare occasions

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11
Q

What are the main considerations of using ultrasound?

A
  • Great soft tissue contrast shows internal architecture
  • Operator dependent experience necessary
  • Gas is the death of US
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12
Q

How can you maximise the results of ultrasound?

A
  • Perform AFTER radiography (gel artefact)
  • Sedate
  • Well set-up and quiet, dark room
  • Clip widely
  • Use plenty of gel
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13
Q

Describe blind spot considerations on ultrasound

A
  • Organs within the pelvic canal
  • Assessment of surgical accessibility
  • Vascular malformations (e.g. portosystemic shunts)
  • Ectopic ureters
  • Refer for CT
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14
Q

You can feel multiple masses in different locations in the abdomen of a dog, which modality do you choose?

A

Radiography

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15
Q

You diagnosed a dog with anal sac adenocarcinoma. You want to asses for sacral lymph node metastasis, which modality?

A

CT

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16
Q

You have the suspicion of an intraluminal bladder mass, which modality do you choose?

A

Ultrasound

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17
Q

List the Rontgen signs

A

Number
Size
Shape
Margination
Opacity
Location

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18
Q

Fluid has the same opacity as…?

A

Soft tissue

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19
Q

What is the mass effect?

A

Gives clues about the origin of masses/space-occupying lesions or in some cases that there is a mass at all

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20
Q

Describe dystrophic mineralisation

A

Secondary to tissue damage - focal lesion
- Adrenal (cats)
- Fat necrosis
- Tumours, abscesses

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21
Q

Describe metastatic mineralisation

A

Secondary to hypercalcaemia - mineralisation of gastric mucosa, aortic wall, etc
- Toxic
- Uraemia
- Paraneoplastic

22
Q

Describe the normal peritoneum

A
  • Space around the organs lined by serous membrane
  • Contains a tiny bit of fluid
23
Q

What is the key role of the omentum in abdominal radiography?

A

Contains fat - key to abdominal contrast and serosal detail

24
Q

What are some causes of a loss of serosal detail in the abdomen?

A
  • Lack of fat: no contrast in the animal e.g. emaciated animals
  • Brown fat/young animal
  • Peritoneal fluid
  • Perintonitis
  • Carcinoma-tosis/sarcoma-tosis
  • Visceral crowding
25
Q

Why is there a loss of serosal detail in brown fat/younger animals?

A

Has a higher water content so has a soft tissue opacity on radiograph so young animals will have a lack of detail

26
Q

How does peritonitis cause a loss of serosal detail?

A

Due to inflammatory cell infiltration of fat

27
Q

How does a carcinoma-tosis/sarcoma-tosis lead to a loss of serosal detail?

A

Metastases of lots of small nodules within the mesentery which are displacing the normal fat content – too small to be appreciated as nodules

28
Q

How does visceral crowding lead to a loss of serosal detail?

A

If you have a large mass everything will be displaced

29
Q

What is a pneumoperitoneum?

A

Gas within the peritoneal space

30
Q

What are the 3 DDx of a pneumoperitoneum?

A
  1. Most common = ruptured GIT = septic abdomen - Emergency – need to be treated immediately
  2. Post surgery (up to 4 weeks)
  3. Penetrating trauma
31
Q

How does a pneumoperitoneum appear on radiography?

A
  • Increased contrast between gas and soft tissue
  • Highlighting of the serosal surface of organ
  • Gas bubbles that do not conform to GIT
  • Usually in conjunction with loss of serosal detail (peritonitis/fluid)
32
Q

Describe the normal appearance of the liver on radiography

A

Most cranial organ in the abdomen
Acute ventrocaudal angle
Just poking past the costal arch

33
Q

Describe why you would assess the gastric axis on radiography

A
  • Fix a point in the middle of the fundus
  • Draw a line to the middle of the pylorus
  • Axis should be parallel to the last rib or roughly perpendicular to the spine
34
Q

Describe the features of a generalised hepatomegaly on radiography

A

Rounded margins
Extending further caudal to the costal arch
Caudally displaced gastric axis

35
Q

List the potential causes of a generalised hepatomegaly

A

Nodular hyperplasia
Lymphoma
Diffuse mets
Acute hepatitis
Metabolic hepatopathy (e.g. diabetes, steroid therapy)

36
Q

Describe the features of a focal hepatomegaly on radiography

A

Mass effect depending on which part is affected

37
Q

List the potential causes of a focal hepatomegaly

A

Neoplasia
Other mass (e.g. abscess)

38
Q

What are the major DDx of Microhepatia

A

Vascular:
- Portosystemic shunt
- Primary portal vein hypoplasia
Inflammatory:
- Chronic hepatitis with fibrosis/cirrhosis

39
Q

What are the major DDx of Microhepatia

A

Vascular:
- Portosystemic shunt
- Primary portal vein hypoplasia
Inflammatory:
- Chronic hepatitis with fibrosis/cirrhosis

40
Q

Describe how Microhepatia presents on radiography

A

Contained within the costal arch
Little soft tissue cranial to the stomach
Cranially displaced gastric axis

41
Q

Describe the normal appearance of the spleen on radiography

A

Tail: Flat triangle just caudal to the liver ventrally - mobile
Head: Flat triangle on the left, ‘superimposing’ the right kidney - fixed to stomach
Body: connecting both, left, often not clearly visible

42
Q

Describe the appearance of splenomegaly on radiography

A

Subjective assessment of size
Often rounding of the margins
Tail caudally displaced (?)
In cats: Tail visible ventrally!
Mass effect

43
Q

Describe the causes of splenomegaly due to a splenic mass

A

Neoplasia: dogs - haemangiosarcoma, cats - mast cell tumour
Haematoma
Nodular hyperplasia

44
Q

List some causes of generalised splenomegaly

A
  • Sedation/GA
  • Infiltration (lymphoma)
  • Inflammation (hyperplasia, splenitis)
45
Q

Describe the features of the normal retroperitoneum

A
  • Dorsal to the peritoneal cavity
  • Contains kidneys and ureters, bladder neck, great vessels, adrenal glands and lymph nodes, prostate etc.
  • Continuous with mediastinum cranially
  • Normal fat opacity (often streaky)
46
Q

Describe the features of the normal retroperitoneum

A
  • Dorsal to the peritoneal cavity
  • Contains kidneys and ureters, bladder neck, great vessels, adrenal glands and lymph nodes, prostate etc.
  • Continuous with mediastinum cranially
  • Normal fat opacity (often streaky)
47
Q

Describe the features of retroperitoneal masses

A
  • Can arise from any retroperitoneal organ (common kidneys and lymph nodes)
  • Or can be fluid (effusion/haemorrhage)
  • Mass effect: Displacing peritoneal organs ventrally
  • Abnormal soft tissue opacity
48
Q

Describe the features of the adrenal glands on radiography

A

Normally not visible on radiographs
Retroperitoneal
May mineralised in old cats (incidental)

49
Q

How to adrenal masses appear on radiography?

A
  • Mineralisation in dogs is associated with neoplasia (but not all tumour mineralise)
  • Mass effect: displace kidney laterally and/or ventrally
  • Common neoplasia: adenoma/-carcinoma and phaeochromocytoma
50
Q

Describe the normal and abnormal appearance of abdominal LNs on radiography

A
  • Normally not visible on radiographs
  • Mass effect when enlarged
  • Soft tissue mass

Y4 SA - Internal medicine (7 decks)

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