GI Imaging

Question 1

What are the different imaging modalities used for the liver?

Answer 1

1st line - Ultrasound.
CT is often used but the sensitivity is reduced if there is fatty liver.
MRI is the most sensitive and specific but less consistent image quality

Question 2

What are the different imaging modalities for the biliary tree?

Answer 2

1st line is ultrasound, useful for looking for stones, gall bladder inflammation and bile duct dilitation.
2nd line is MRI/CT. MRI tends to be used for benign causes of biliary obstruction and CT for malignancy

Question 3

What imaging techniques is specifically used to look for gall stones IN the ducts?

Answer 3

MRCP. This is because ultrasound imaging cant visualise the bile ducts. It can also be used to look for primary sclerosing cholangitis

Question 4

What imaging modalities are used for the small bowel?

Answer 4

Both CT and MRI enterography are used. MRI enterography is often the first line for young patients. MRI also allows for multiple images to be taken. CT is quick but only one image can be taken

Question 5

What imaging modality is used for the large bowel?

Answer 5

CT colonoscopy or standard CT.
This gives an alternative for colonoscopy and allows for a virtual CT colonoscopy.

Question 6

Explain the procedure of a CT colonoscopy

Answer 6

• Bowel is cleansed and tagged with iodine.
• The bowel is distended with CO2.
• IV contrast is injected and supine and prone CT scans are taken.

Question 7

What is the radiological appearence of liver cirrhosis?

Answer 7

• Hypertrophy of the caudate lobe and left lobe along with atrophy of the right lobe.
• Irregular boarder and nodules

Question 8

What is a specific feature of hepatocellular carcinoma on MRI scans?

Answer 8

• Hypervascularity followed by washout when contrast is used. This can differentiate HCC from cholangiocarcinoma

Question 9

What is the appearence of a small bowel obstruction on abdo X ray?

Answer 9

• Dilation of the small bowel (over 3cm) and a coiled spring appearence. Straight lines across the bowel (valvulae conniventes) make it identifiable as small bowel.

Question 10

What is the appearence of a sigmoid volvulus and a caecal volvulus

Answer 10

Sigmoid - Coffee bean appearence
Caecal - fetal appearence

Question 11

What is a Rigler’s sign?

Answer 11

This occurs when there is free fluid in the abdomen resulting in both sides of the bowel becoming visrable

Question 12

What are the abdominal X ray appearances of inflammatory bowel diseases

Answer 12

• Thumbprinting - mucosal thickening of haustra due to inflammation and oedema.
• Lead-pipe colon: loss of normal haustral markings secondary to chronic colitis.
• Toxic megacolon

Question 13

What is a volvulus and its complications

Answer 13

It is a twisting of a loop of intestine. Most commonly this occurs at the sigmoid colon. It will present with clinical features of bowel obstruction (colicky pain, abdo distention and absoloute constipation). Complications include nectotic bowel, perforation