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Y4 - Small Animals > Approach to abdominal imaging and imaging of parenchymal organs > Flashcards

Approach to abdominal imaging and imaging of parenchymal organs Flashcards

1
Q

Why would be want to image the abdomen?

A
  • Biopsy
  • Hernias
  • Stomach torsion
  • Pregnancy
  • RTAs
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2
Q

‘What are radiographic considerations?

A
  • Low kV-high mAs technique to avoid scatter radiation and improve contrast resolution
  • Intrinsically poor contrast mostly soft tissue with only
    a little fat to give contrast
  • High/long mAs increases susceptibility to motion artefact
  • Expose during expiratory pause (end of expiration)
  • VD instead of DV view to “spead out” organs
  • reduce superimposition
  • Remember: “One view is one view too few!”
  • Take a right lateral and ventrodorsal projection
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3
Q

What is contrast medium - advantages/disadvantages?

A
  • Helpful for urinary tract studies
  • Rarely useful in gastrointestinal tract studies (use ultrasound)
  • Essential for abdominal CT
  • Require good preparation and time and money!
  • Correct contrast medium for the right indication
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4
Q

What are positive contrast media (bright)

A
  • Iodine containing - GIT, urinary tract + myelography = SAFEST
  • Barium - GI only
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5
Q

What are negative contrast media? (dark)

A
  • Room air - limited use
  • CO2 or N2O
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6
Q

What happens if barium escapes?

A
  • Severe granulomatous inflammation + death
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7
Q

What can use of gas / air cause?

A
  • Fatal air embolism - on rare occasions
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8
Q

What are ultrasound considerations?

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

For best results:
* Perform AFTER radiography (gel artefact)
* Sedate
* Well set-up and quiet, dark room
* Clip widely
* Use plenty of gel

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9
Q

Where are blind spots with ultrasound or radiography?

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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10
Q

What are Rontgen signs?

A
  • Number
  • Size
  • Shape
  • Margination
  • Opacity - (gas, fat, soft tissue, bone/mineral, metal)
  • Location
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11
Q

What would you consider before diagnosis?

A
  • normal anatomy
  • Pattern of pathology
  • Radiological findings
  • CLinical history + signalment
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12
Q

What are the different opacities?

A
  • Gas = darkest
  • Fat
  • Fluid + soft tissue
  • Mineral
  • Metal = brightest
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13
Q

What is mass effect?

A
  • Gives clues about the origin of masses/space- occupying lesions or in some cases that there is a mass at all
  • Displacement of other organs
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14
Q

What are 3 forms of mineralisation?

A
  • Dystrophic - secondary to tissue damage
  • Metastatic - secondary to hypercalcaemia
  • Other
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15
Q

What are examples of dystrophic mineralisation?

A

PREVIOUS PROBLEM
* Adrenal (cats)
* Fat necrosis (bates bodies)
* Of tumour, abscesses …

  • Usually see a focal lesion
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16
Q

What are examples of metastatic mineralisation?

A

CURRENT PROBLEM
* Toxic
* Uremia (gastric)
* Paraneoplastic - secondary to a tumour - lymphoma

  • Usually see mineralisation of gastric wall
17
Q

What are examples of other mineralisation?

A
  • Urinary calculi
  • Ingesta
  • Osseous neoplasia
18
Q

What can cause loss of serosal detail?

A
  • lack of fat = effacement - no margination of organs
  • Peritoneal fluid - secondary to R-CHF
  • Brown fat / young animals - contains a lot of water
  • Peritonitis
  • Carcinomatosis / sarcomatosis - micronodules in organs replace fat
  • Visceral crowding
19
Q

What causes pneumoperitoneum?

A
  • Post surgery - up to 4 weeks
  • Ruptured GIT - septic abdomen
  • Penetrating trauma
20
Q

What is seen with pneumoperitoneum?

A

Increased contrast between gas + soft tissue
- diaphragm + intestinal walls more obvious to see
* Gas bubbles not within GIT
* Loss of serosal detail

21
Q

What is seen with the liver on radiograph?

A
  • Most cranial organ
  • Acute ventrocaudal angle
  • Just poking past the costal arch
  • Gastric axis:
    -Fix a point in the middle of the fundus
    -Draw a line to the middle of the pylorus
22
Q

What is seen with hepatomegaly?

A

Generalised
* Rounded margins
* Extending further caudal to the costal arch
* Caudally displaced gastric axis
e.g. nodular hyperplasia, lymphoma, acute hepatitis, metabolic hepatopathy

Focal
* Mass effect depending on which part is affected
e.g neoplasia, abscess

23
Q

What is small liver called? What is seen?

A

MICROHEPATIA

  • Contained within the costal arch
  • Little soft tissue cranial to the stomach
  • Cranially displaced gastric
24
Q

What can cause microhepatia?

A
  • Vascular - portosystemic shunt / primary portal vein hypoplasia
  • Inflammatory - chronic hepatitis with fibrosis/cirrhosis
25
Q

What does the normal spleen look like?

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
26
Q

What is seen with splenomegaly?

A
  • Subjective assessment of size
  • Often rounding of the margins
  • Tail caudally displaced
  • In cats: Tail visible ventrally!
27
Q

What is seen with a 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)
28
Q

What can cause splenic masses? (abnormal shape)

A
  • Neoplasia (dog = haemangiosarc, cat = MCT)
  • Haematoma
  • Nodular hyperplasia
29
Q

What can cause generalised splenomegaly? (normal shape)

A
  • Sedation / GA
  • Infiltration - lymphoma
  • Inflammation - hyperplasia + splenitis
30
Q

What are 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
31
Q

Adrenal glands are not visible on radiographs, when might you see them in cats?

A
  • Old cats = mineralised adrenal glands
32
Q

What are adrenal masses?

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
33
Q

What is seen with lymph nodes on radiograph?
What are the retroperitoneal + peritoneal lymph nodes?

A
  • Normally not visible on radiographs
  • Mass effect when enlarged
  • Soft tissue mass
  • Retroperitoneal lymph nodes
    para-aortic (including renal), medial iliac, internal iliac, sacral
  • Peritoneal lymph nodes
    gastric, pancreaticoduodenal, splenic, jejunal and colic
34
Q
A

Y4 - Small Animals (105 decks)

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