imaging digestive system Flashcards
how do we image digestive system?
XRs
Fluoroscopy- barium swallows, meals, defaecating proctograms
CT- abdominal / pelvis CT. CT colonography
MRI- MR enterography
Ultrasound - abdominal ultrasound, small bowel ultrasound
Nuclear medicine- gastric emptying scans, meckel scans.
how to see small and large bowel on a AXR
How do we look at bowel on a AXR?
Remember the 3,6,9 rule
It can be really hard to differentiate between large and small bowel on an AXR
Look for valvular conniventes and the teniae coli
Small bowel is normally more central
Large bowel often has a mottled appearance due to gas within faeces
AXR stomach
The stomach may be visible if it contains gas. However, if it is completely empty or completely fluid filled you may not see it.
Generally, lies at around T10 level
AXR liver
Liver – the liver lies in the right upper quadrant and is a generally homogenous grey density
The superior edge forms the contour of the right hemidiaphragm
Sometimes breast shadow can overlie and make it difficult to see
You will generally only see the gallbladder if its abnormal or absent!
The liver doesn’t normally extend lower than the lower pole of the kidney
AXR liver normal variant
riedel lobe
Common anatomical variant of the liver
Can be mistaken for a mass
It is where the right lobe of the liver is larger than normal and extends caudally in the abdomen
Seen in up to 31% of patients, with a female predominance
CT colonography
Screening test for colorectal cancer
After failed or unsuitable endoscopy or patient choice
Shows the colon in much more detail than a normal CT
Patient drinks contrast – generally gastrografin
Gas is inserted to inflate the bowel
CT scan of the liver
Generally done as a triple phase scan
Looks for liver lesions and metastases
3 phase
Late arterial
Portal venous phase
Delayed phase
There can also be an additional non contrast scan
The liver gets approximately 25% of its blood supply from the hepatic artery and 75% from the portal vein so needs many phases for accurate assessment
what are the 3 phases in CT scan of the liver, and what can you see
It can be hard to work out what a liver lesion is, but this helps.
Late arterial
Will see the portal vein, not the hepatic vein
Good to look for hepatocellular cancer
Portal venous
Will see portal veins and the hepatic vein
Will see if the liver is fatty
Good to look for very vascular liver tumours
Delayed phase
Some tumours may enhance compared to the rest of the liver in this late stage
MRI enterography
Non invasive technique for assessing the small bowel
Why is this good for patients with inflammatory bowel diseases?
It can demonstrate acute inflammation from disease exacerbation and complications
Patients have to drink mannitol
what are advantages and disadvantages of MRI enterography
Advantages
noionising radiation
excellent soft tissue contrast resolution
images can be acquired in customised planes
Disadvantages
longer scanning time
more susceptible to motion and breathing artifacts
MRI incompatible implants or devices may preclude the scan
contraindicated to claustrophic patients
fluoroscopy- barium swallow
Barium swallow
Dedicated test of the pharynx, oesophagus and proximal stomach
Patient drinks barium when instructed
Dynamic so good for functional disorders
Can be used to help patients rehabilitating after stroke or with neuro or muscular degenerative disorders
fluoroscopy- small bowel follow through
Small bowel follow through
Evaluates the small bowel dynamically
Patient drinks barium and water
Sometimes ant sickness medication is given
Is being less utilised in favour of CT or MRI
fluoro- defecating proctograms
Defecating proctograms
Evaluates the pelvic floor in patients with difficulties in defaecation or with constipation
normal variants and different appearances in imaging the digestive system
Reidel’s lobe
Surgery
Cholecystectomy
Weight loss procedures
what is a cholecystectomies
Nearly all laparoscopic
Gallbladder removed due to stones or polyps
what is a weight loss procedure commonly used?
Gastric band
Performed laparoscopically, a silicone band device is placed around thestomachto reduce its volume. The band is adjustable via a port placed in the subcutaneous tissues of the abdomen, which can be filled with a variable volume of liquid to tighten or release the band constriction.
