Imaging of gastrointestinal disease

Question 1

Why would you not radiograph the pancreas?

Answer 1

• Normal pancreas is not observed on plain radiographs
• Medial to duodenum, between gastric body and transverse colon, medial to spleen and cranial to left kidney
• US much more useful

Question 2

What is seen with pancreatic enlargement?

Answer 2

• Due to pancreatitis or neoplasia
• Mass effect
  -local loss of serosal detail

Question 3

What is seen with megaoesophagus?

Answer 3

• Segmental or generalised dilation
• May cause ventral deviation of the trachea and widening of the mediastinum.
• Tracheo-oesophageal stripe sign (summation of tracheal wall and oesophageal wall).
• Think about disease secondary to oesophageal disease (aspiration pneumonia)

Question 4

What suggests foreign body in oesophagus?

Answer 4

• Highly suggestive history
• Predelection sites: Thoracic inlet, heart base and cranial to the diaphragm/cardia.
• Well-defined “mass” where bordered by lung/gas (orthogonal views)

Question 5

Why would you not use barium contrast with foreign body?

Answer 5

• Suspected perforation - would leak to mediastinum
• use non-ionic iodine contrast

Question 6

What is seen with the stomach on radiograph?

Answer 6

• Positioned within the costal arch in the cranial abdomen, directly caudal to the liver.
• Divided into several compartments: cardia, fundus, body, pyloric antrum/pylorus.
• Gas distribution will change with recumbency.
• Do not mistake fluid filled pyloric antrum for a mass

Question 7

What are the 5 layers from outside to in on ultrasound of the stomach?

Answer 7

• Serosa
• Muscularis (hypoechoic-dark)
• Submucosa
• Mucosa (hypoechoic-dark)
• Lumen

Question 8

What can cause gastric dilation?

Answer 8

Gas dilation (darker - larger volume of gas) =
* Aerophagia
* GD/ GDV

Fluid + gas dilation =
* Pyloric outflow obstruction
* Functional ileus

Question 9

What is seen with GDV on radiography?

Answer 9

• Marked gas dilation and displacement of gastric compartments
• Fundus displaced caudoventrally and right.
• Pyloric antrum displaced craniodorsal and left.
• Compartmentalisation with a dividing soft tissue band (“shelf”)
• Mass effect on other organs

Question 10

What is GDV if no rotation around longitudinal axis?

Answer 10

• Just gastric dilation

Question 11

What can cause small intestinal dilation?

Answer 11

• Mechanical obstruction = foreign body / tumour
• Functional ileus = severe inflammation, toxic, stress
• No 1 loop should be more than 2x diameter of any other loops

Question 12

What is obstructive pattern of the SI?

Answer 12

• Fluid and/or gas dilation proximal to the obstruction.
• Creates “two populations of intestine”
• one abnormal proximal and
• one normal distal population to obstruction
• Take care not to confuse large and small intestinal loops

Question 13

What is seen with linear foreign body?

Answer 13

• Plication/hair-pin bends, bunching
• Triangular/tear-drop shaped gas bubbles
• +/- localised peritonitis (loss of serosal detail, streaky
  appearance
• Signs of obstruction

Question 14

What is seen with intussusception?

Answer 14

• Most commonly in young dogs and cats, in older patients usually secondary to other pathology
• Ovoid/elongated ST mass/dilation
• Possibly crescent shaped gas opacity between intussusceptum (inner) and intussuscipiens (outer)
• No “normal” caecal gas, shortened colon

Question 15

What is seen with intussusception on ultrasound?

Answer 15

• Onion ring / bullseye appearance

Question 16

What is seen with SI neoplasia?

Answer 16

US
* Most commonly seen with neoplasia (lymphoma, adenocarcinoma, leiomyosarcoma, GIST, in cats MCT)
* Loss of wall layering
* May have central gas containing lumen (distal shadowing)
* May see signs of obstruction
* Assess local lymph node