Imaging of the GI Tract Flashcards
What are some ways of imaging the GI tract?
- conventional x-ray
- ultrasound
- CT
- MRI
- nuclear medicine imaging
- hybrid imaging
What would the first line imaging be for an acute abdomen case? What would you be looking for on imaging?
- x-ray
- looking for soft tissue, gas, calcium or foreign object
What is the normal gas distribution in an abdominal x-ray?
- upper portion of stomach
- 2/3 gas filled loops in small intestines
- peripheral and lower portion of large intestines
How do you distinguish between small and large intestines?
- small intestine: central, thin folds over entire circumference
- large intestines: around periphery of abdomen, thicker, incomplete folds
Describe what you would see in an x-ray of a small intestines obstruction
- dilation of small intestines (>2.5cm)
- more prominent folds
- ‘coiled spring appearance’
- less or no gas in large intestine
Describe what you would see in an x-ray of a large intestines obstruction
- distended gas filled loop
- air-fluid levels at periphery
- caecum distended most
- less/no gas beyond level of obstruction
What can cause gas to be outside the intestine or stomach?
- intestinal perforation
- introduced from outside by injury or operation
Where would you look on a film to see if there is any gas in the wrong place?
- below diaphragm (in erect)
- surrounded intestines (rigler’s sign: has within and outside intestine outlining wall)
- gas collection in different shape
- gas outlining ligaments and uscles
Describe what you would see in a film of a patient with sigmoid volvulus?
a characterisic ‘coffee bean’ appearance
What are some abnormal calcifications?
- stones (gall, renal, ureteric, bladder)
- in vessel wall (atherosclerosis, diabetes, aneurysm)
- in organs (pancreas, renal cyst, uterine fibrinoids)
What does fluoroscopy involve?
contrast barium or thin water soluble contrast swallowed
- barium meal (if looking at stomach)
- follow through (if looking at small intestines)
- enema (if looking at large intestines - in this case, contrast is not swallowed but inserted para-rectally)
What are the general advantages of ultrasound?
- no radiation (good for children and pregnant ladies)
- easily available
- can be done at bedside
- can use color doppler to look at blood supply to organ as well
What are the abdominal imaging advantages of ultrasound?
- can be used for quick assessment of abdomen in trauma cases
- best test for gall stones and gallbladder inflammation
- well-known for use of assesment of foetal well-being
- useful in assessing complications related to pregnancy (first line viewing uterus and ovaries)
What stage is a CT scan used for abdo imaging?
- 2nd line imaging investigation after X-ray and ultrasound to clarify findings further
- sometimes used as 1st line if clinical suspicion is high
What are the advantages of CT scan?
- can pick up cancer early
- allows for cross-sectional evaluation unlike x-ray
- gives definitive diagnosis in most cases with positive findings on x-ray/ultrasound
