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S3: Gastrointestinal > 10a.) Imaging of GI Tract > Flashcards

10a.) Imaging of GI Tract Flashcards

1
Q

State 5 generic ways of imaging the GI tract; provide some examples for each

A
  • Plain x-rays
    • Abdominal x-ray (AXR)
    • Chest x-ray (CXR)
  • Contrast studies
    • Barium swallow
    • Barium enema
    • Barium meal/follow through
    • Water soluble contrast studies
  • Ultrasound
  • Cross sectional imaging
    • Computed tonography (CT)
    • Magnetic resonance imaging (MRI)
    • PET-CT
  • Angiography
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2
Q

State 3 reasons why a doctor may request an AXR

A
  • Acute abdo pain
  • Small or large bowel obstruction
  • Acute excerbation of IBD

NOTE: used to use for renal colic but now CT is first line

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3
Q

What projection do we use on an AXR?

A

Anterior-posterior

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4
Q

State what features you can see on AXR

Think ABCDE

A
  • Bowel gas
  • Soft tissue structures
  • Bones

OR…

  • A= air/gas
  • B= bowel
  • C= calcification & stones
  • D= dem bones
  • E= everything else

Or…. ABDOX

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5
Q

Describe the ABDOX mnemonic in full

A

Used as a checklist of thing to look for on an AXR:

  • A= air: where it should and shouldn’t be
  • B= bowel: size and wall thickness
  • D= dense structures: calcification, bones
  • O= organs & soft tissues: liver, spleen, kidneys
  • X= eXternal: objects & artefacts
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6
Q

Describe whether the hollow part of GI tract would be visible if filled with:

  • Gas
  • Gas & fluid
  • Fully fluid
A
  • Gas= visible
  • Gas & fluid= visible
  • Fully fluid= not visible
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7
Q

State what each of the following contains in terms of solid, liquid and gas and also state whether transit time is slow, medium or fast?

  • Stomach
  • Small bowel
  • Colon
A
  • Stomach: fluid & lots of gas- medium
  • Small bowel: fluid - fast
  • Colon: faeces & gas - slow
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8
Q

Describe the appearance of small bowel on AXR

A
  • Central position
  • Valvulae conniventes (lines that cross entire bowel wall)
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9
Q

Describe the apperance of large bowel on AXR

A
  • Peripheral position
  • Haustra (seen as incomplete lines across bowel wall)
  • Faeces & gas present dueto slow transit time of large bowel
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10
Q

Transverse colon can hang down into pelvis; true or false?

A

True

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11
Q

State the diameter of:

  • Small bowel
  • Large bowel
  • Caecum

… if there is a bowel obsturction in each of these areas

A
  • Small bowel obstruction: >3cm
  • Large bowel obstruction (with incompetent ileocaecal valve): >6cm
  • Large bowel obstruction (with competent ileocaecal valve): caecum >9cm

RULE OF 3’s: 3, 6, 9

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12
Q

What does this image show?

A

Small bowel >3cm therefore small bowel obstruction

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13
Q

Describe how someone with a small bowel obstruction may present

A
  • Nausea & vomitting (EARLY)
  • Distentsion (mild)
  • Absolute constipation (LATE)
  • Colicky pain
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14
Q

State some possible causes of smal bowel obstruction

A
  • Adhesions
  • Hernias (inguinal, femoral, incisional)
  • Tumours
  • Inflammation
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15
Q

What does this image show?

A

Large bowel obstruction

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16
Q

Describe how someone with a large bowel obstruction may present

A
  • Vomitting (late, faeculant)
  • Distensionn (significant)
  • Pain
  • Absolute constipation
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17
Q

State some possible causes of large bowel obstruction

A
  • Colorectal cancers
  • Diverticular stricture
  • Hernia
  • Volvulus
  • Pseudo-obstruction
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18
Q

What is volvulus?

Which part of bowel is it common in?

Describe appearance on AXR

A
  • Twisting of bowel its mesentery (the enclosed bowel loops then dilates which can lead to perforatin or ischaemia. Bowel proximal also dilates)
  • Sigmoid colon
  • Coffee bean sign that starts in left iliac fossa and goes towards right upper quadrant
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19
Q

What does this AXR show?

A

Sigmoid volvulus (coffee bean sign starting in LIF towards RUQ)

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20
Q

Is AXR the gold standard for infection and inflammation? Discuss

A
  • Not the gold standard. But may see acute or chronic changes e.g.:
    • Mucosal thickening
    • Featureless colon
    • Bowel wall thickening
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21
Q

What is toxic megacolon?

Who is it common in?

What are some complications of toxic megacolon?

A
  • Abnormal dilation of colon (megacolon part) that is very serious/can be life threatening (toxic part)
  • Common in IBD patients (more so in UC)
  • Complications: sepsis, perforation,
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22
Q

State some features of toxic megacolon on AXR (3)

A
  • Colonic dilation
  • Oedema
  • Pseudopolyps
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23
Q

What is meant by ‘lead pipe colon’ and who is it comon in?

A
  • Featureless colon with lack of haustra
  • Common in UC patients
24
Q

What does this AXR show?

A

Lead pipe colon

25
Q

What is meant by thumb printing and what does it suggest?

A
  • Oedematous thickened haustra and bowel wall
  • Suggests active inflammation (often in UC)
26
Q

Where is the liver on this AXR?

A
27
Q

State some of the organs you can see on AXR

State some of the bones you can see on AXR

A
28
Q

Where is the spleen on this AXR?

A
29
Q

Where are the kidneys on this AXR?

A
30
Q

Where is the bladder on this AXR?

A
31
Q

On AXR you can see 3 types of calcification; state these

A
  • Renal canaliculi
  • Vascular calcification
  • Calcification of pancreas following chronic inflammation
32
Q

What does this image show?

A
33
Q

State some causes of perforation

A
  • Peptic ulcer
  • Diverticular
  • Tumour
  • Obstruction
  • Trauma
  • Iatrogenic
34
Q

What is the imaging of choice for perforation?

A

Erect chest x-ray- see gas under diaphragm (pneumoperitoneum)

35
Q

What does this abdominal CT show?

A

Pneumoperitoneum

36
Q

Foreign bodies are also visible on AXR; true or false?

A

True

37
Q

What two contrasts can be used to define hollow viscera?

A
  • Water soluble
  • Barium
38
Q

Describe the difference between a barium swallow, meal, follow through

A

Drink barium then take x-rays:

  • Swallow: looks at how it moves through oesophagus
  • Meal: looks at stomach
  • Follow through: looks at small intestine
39
Q

Describe a barium enema

A

Barium liquid passed into large bowel through anus then x-rays taken

40
Q

Discuss the advantages and disadvantages of an abodminal CT

A

Advantages

  • High resolution
  • Can add contrast to get btter image

Disadvantages

  • High dose radiation
41
Q

Individual images from a CT scan can be reformatted and combined to produce a 3D representatoin of the scanned anatomy e.g. a virtual colonscopy; true or false?

A

True

42
Q

What is contrast induced nephropathy?

A

Impairment of renal function- measured as either a 25% increase in serum creatinine from baseline or a 0.5mg/dL increase in absolute SCr value within 38-72 hours after intravenous contrast administration

43
Q

Does MRI use ionising radiation?

A

No

44
Q

Discuss advantages and disadvantages of abdo CT

A

Advantages

  • Detailed, high contrast image
  • No radiation

Disadvantages

  • Time consumiing
  • Expensive
45
Q

Discuss the advantages and disadvantages of abdominal ultrasound

A

Advantages

  • Cheap
  • Portable (fast)
  • No radiation

Disadvantages

  • Highly user dependent
46
Q

What is abdominal ultrasound often used to visualise?

A

Biliary tree (for gallstones and dilated bile duct)

47
Q

What are abodminal angiograms used for?

A

To detect:

  • Aneuryseums
  • Stenosis
  • Blockage of vessel
48
Q

Be able to label CT of abdo

A
49
Q

Be able to label MRI of abdo

A
50
Q

Be able to lable MRI of abdo

A
51
Q

Be able to label MRI of abdo

(L1)

A
52
Q

Be able to label CT of abdo

(T12)

A
53
Q

Be able to label MRI of abdo

(L4)

A
54
Q

What is paralytic ileus?

A

Intestinal blockage in the absence of an actual physical obstruction; due to malfunction in nerves and muscles that impairs digestive movements

55
Q

What organ is this an AXR?

A

Stomach

S3: Gastrointestinal (18 decks)

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