Imaging of the GI Tract Flashcards
Name some imaging methods for looking at the GI tract
Conventional X-ray, ultrasound, CT, MRI and others which include nuclear medicine and hybrid imaging
What is first line imaging in case of an acute abdomen and what are you looking for?
- X-ray;
Looking for gas, soft tissue, calcium or foregin object
What is the normal gas distribution in the GI tract?
- Portion of upper stomach,
- Small intestines have 2/3 gas filled loops and,
- Distal portion of the large intestine
How can you tell if gas is in the small or large intestine?
Small - central thin folds across entire circumference.
Large - On the periphery, thicker and incomplete folds
What would indicate small intestine obstruction?
- Distention (over 2.5cm)
- Multiple central fluid levels,
- Less gas or no gas in large intestines
What would indicate large intestine obstruction?
- Distended gas filled loop or air fluid levels at periphery,
- Caecum over 9cm and the rest over 5/6cm,
- Look for haustra to differentiate,
- Less or no gas beyond the level of obstruction
Gas outside of the intestine or stomach could indicate?
Intestinal perforation which could be induced by injury or operations
Where should you look for gas in the wrong place?
- Below diaphragm in errect films,
- Surrounding the intestines,
- Gas collection which looks of different shapes,
- Gas outlining ligaments and muscles
Abnormal calcifications can be due to?
- Stones in the gallbladder, kidneys, ureteric or bladder.
- Calcification in the vessel wall,
- Calcification in organs
What does fluoroscopy involve?
Contrast (barium or thin water soluble contrast) via a meal, follow through or enema
What are some advantages of ultrasoun?
No radiation so can be used on pregnant women and children, easily available, can be done at patient bedside , used for quick assessment of the abdomen in trauma, and with the help of Doppler the blood supply to an organ can be assessed.
What scanning method is first line to image uterus and ovaries
Ultrasound
What are the important clinical features of a CT scan
- It is commonly 2nd line imaging for further imaging but can be 1st line if clinical suspicion is high.
- Can pick up cancer early,
- Allows for cross sectional evaluation
- Cons = radiation
What are some of the pros of MRI scanning
- No radiation,
- Cross sectional imaging,
- Better soft tissue resolution,
- Can be used on children and pregnant women after 1st trimester
What are some of the cons of MRI scanning
- Availability,
- Length of time,
- Not safe for some patients (aneurysm clips, pacemakers ect)
- Some patients may find it difficult,
- Safety in pregnant is not proven
