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Flashcards in Imaging the GI tract Deck (22)

When would you use an ultrasound to image the GI tract?

cholelithiasis, acute cholecystitis


When are nuclear medicine scans helpful?

bile leaks
cystic duct obstruction


When should you get a KUB? What will it tell you?

Indicated for abdominal pain. Can rule out obstruction/perforation.


Why is an upright image required with a KUB?

Will show you air fluid levels in the bowel. If uneven, this tells you that PERISTALSIS is INTACT


When would you use fluoroscopy?

Pain, dysphagia, diarrhea, colon cancer screening


What are the two main methods with fluoroscopy?

1. double contrast: air and barium shows mucosal detail, i.e. ulcerations, neoplasms

2. Single contrast: Barium only shows peristalsis , walls, folds, caliber


When would you order an abdominal CT?

pain, bowel pathology, tumors, weight loss, vague symptoms


When would you use positive contrast (barium)?

To differentiate fluid collections from bowel


When would you use negative contrast (water, low density)

Good for evaluating bowel mucosa and wall


If you wanted to evaluate a liver met, what would you order?

CT with contrast, and "prescribed" attenuation time


When would you order an MRI to evaluate the abdomen?

AFTER an US or CT has detected an abnormality which needs more detail. OR if there are contraindications.

Exception: MRCP for Crohns


What are causes of bowel wall thickening?


Will see thickening of wall or loss of haustra/circularis plicae


What does CT show you with bowel thickening?

It's sensitive, but not that specific. Can show you inflammation


Can radiography show you bowel thickening?

Yes if air filled.


What does inflamed mesenteric fat look like on CT?

"fat stranding"
Sometimes enlargement. Can see this with pancreatitis


What are the imaging changes you would see with vasodilitation?

1. Increased size of vessels in fat
2. Bowel Mucosal hyperenhancem
3. Organs have variable enhancement


What imaging changes would you see with increased extra-vascular fluid?

Increased density of fat
Decreased density or organs
Thick bowel wall folds


What are the benefits of each of the following in evaluating an inflammatory process in the abdomen?

1. CT with contrast
2. Radiography
3. US
4. MRI

CT: fast, sensitive
Xray: Non specific inflammation of organs. May see mass effect from adjacent inflammation
US: Cannot see through fat. Bad choice
MRI: expensive/costly


What will you see on imaging with obstruction?

Dilation above
Decompression below
Also, little or no air in colon seen because cannot move contents along!
Strings of pearls: air trapped in plica circularis


What is a diffuse ileus?

Absence of peristalsis, with accumulation of secretions and air in both small and large bowel. Will see air fluid levels


What are causes of a diffuse ileus?

1. Post operative
2. Drugs
3. Adjacent inflammatory process


How will hypervascular tumors show up on CT?

earlier than the liver. Tumor will have max attenuation before the liver.

Hypovascular tumors will show up as opposite of that.