Imaging of the GI tract

Question 1

Why aren’t X-rays very useful for imaging the GI tract?

Answer 1

• Can’t see much
• Still useful in determining bowel obstructions and flare ups of IBD

Question 2

What does ABDO X stand for when looking at abdominal X-rays?

Answer 2

• A = Air
• B = Bowel
• D = Dense structures and calcification
• O = Organs and soft tissues
• X = eXternal objects & lines & tubes

Question 3

How do we differentiate between small and large bowel on an X-ray?

Answer 3

• Small bowel is central
• Valvulae conniventes
• Contains air or fluid
• Large bowel is peripheral
• Haustral folds
• Contains air or faeces

Question 4

What indicates bowel obstruction on an abdominal X-ray?

Answer 4

• Small bowel diameter greater than 3cm
• Large bowel diameter greater than 6cm (9cm for caecum)

Question 5

What are the most common causes of bowel obstruction?

Answer 5

• Sigmoid volvulus - appears like a large coffee bean
• Caecal volvulus

Question 6

What are the signs of colitis that can be seen on an X-ray?

Answer 6

• Thumb print sign
• Bowel wall thickened and oedematous

Question 7

How does toxic megacolon appear on an X-ray?

Answer 7

• Colonic dilatation
• Oedema
• Pseudopolyps

Question 8

What pathologies caused by calcification can be seen on X-ray?

Answer 8

• Renal calculi
• Vascular calcification
• Calcification of the pancreas following chronic inflammation

Question 9

What are common GI contrast studies?

Answer 9

• Swallow test
• Can highlight problems/anatomical variance with stages of swallowing
• And a follow-through which allows contrast to pass into small intestine

Question 10

What is used as a contrast for GI studies?

Answer 10

• Water soluble contrast
• Barium contrast

Question 11

What is ERCP?

Answer 11

• Endoscopic retrograde cholangiopancreatography
• Can be used to image biliary tree
• Can see gallstones

Question 12

What allows the large intestine to be imaged?

Answer 12

• Contrast enema

Question 13

What kind of scan allows us to look at motion of the GI tract?

Answer 13

• Doppler imaging using ultrasound
• Can see peristalsis of bowel
• Can see ulceration

Question 14

What are the pros and cons of using ultrasound for imaging of the GI tract?

Answer 14

• Cheap and portable
• Used to visualise biliary tree (for gallstones and dilated bile ducts)
• Very user dependent

Question 15

What are the pros and cons of using CT to image the GI tract?

Answer 15

• Produces high resolution images of abdomen
• Individual images can be reformatted and combined to produce 3D representation of scanned anatomy
• High dose of radiation

Question 16

What are the pros and cons of abdominal MRI?

Answer 16

• Gives detailed and high contrast images of abdomen
• Can be used with contrast to enhance images
• Very time-consuming

Question 17

What is angiography interventional radiology?

Answer 17

• Used to visualise the inside of blood vessels
• Feed wires into arterial system via femoral vessels
• Contrast blush indicates where bleeding is occurring