IMAGING - Gastrointestinal Tract Flashcards
1
Q
Identify the different anatomical components of the abdomen on this ventrodorsal radiograph
A
2
Q
Identify the different anatomical components of the abdomen on this lateral radiograph
A
3
Q
What are the advantages of radiography when imaging the abdomen?
A
Widely available
Good to visualise organ position
Good to visualise changes in organ size/diameter
Good to visualise gas/mineral opacities
4
Q
What are the disadvantages of radiography when imaging the abdomen?
A
- Any loss of serosal detailing will hinder organ identification and interpretation
- Several views are required which requires patient sedation or general anaesthetic
- Not all organs can be visualised
- Can’t differentiate between soft tissue and fluid opacity
5
Q
Which abdominal organs cannot be visualised using radiography?
A
Pancreas
Adrenal glands
Gall bladder
6
Q
Which contrast mediums can you use for contrast radiography of the abdomen?
A
Barium based contrast
7
Q
What are the advantages of ultrasound when imaging the abdomen?
A
Widely available
Good to visualise free fluid
Good to visualise changes in organ architecture
Good to visualise changes in organ diameter
Real-time imaging
Assessment of motility
Guides fine needle aspirates and biopsies
8
Q
What are the disadvantages of ultrasound when imaging the abdomen?
A
Requires experience
Poor modality for bone and gas
9
Q
What are the advantages of endoscopy when imaging the abdomen?
A
Endoscopy allows for direct visualisation of the gastrointestinal tract
10
Q
What are the disadvantages of endoscopy when imaging the abdomen?
A
Endoscopy is limited to visualisation of the stomach, duodenum and colon
11
Q
Describe the normal anatomical appearance of the liver on radiography
A
Located in the cranial abdomen
Usually contained within the costal arch
Triangular shape on lateral view
Even soft tissue opacity
Sharp caudal-ventral margin
Falciform fat (fat opacity) ventral to the liver on lateral view
12
Q
What is indicated when the liver does not have a sharp caudo-ventral margin?
A
Hepatomegaly
13
Q
What is the gastric axis?
A
The gastric axis is an imaginary line parallel to the ribs, drawn where the stomach overlaps the liver on a lateral radiograph. The gastric axis can be used to evaluate liver size and the position of the stomach relative to other organs
14
Q
How does the normal appaerance of the liver on radiographs differn in young patients?
A
Larger liver relative to their body size
Little serosal fat
15
Q
What are the key signs of hepatomegaly on a radiograph?
A
Rounding of the caudo-ventral margin
Caudo-medial displacement of the gastric axis
Projection beyond the costal arch
16
Q
What are the key signs of microhepatica on a radiograph?
A
Cranial rotation of the gastric axis
17
Q
(T/F) Microhepatica can be a normal breed variation
A
TRUE.
18
Q
What are possible differentials of true microhepatica?
A
Portosystemic shunt
Chronic hepatitis
19
Q
What is a postosystemic shunt?
A
A portosystemic shunt is an abnormal vascular connection that allows blood from the hepatic portal system to bypass the liver and flow into the systemic circulation, allowing metabolic byproducts that are usually removed and detoxified by the liver to accumulate in the circulation
20
Q
How can a portosystemic shunt cause microhepatica?
A
A portosystemic shunt causes blood from the hepatic portal system to bypass the liver resulting in hepatic atrophy due to decreased blood flow
21
Q
Describe the normal anatomical appearance of the liver on ultrasound
A
Generally contained within the costal arch
Sharp margins
Architecture consisting of homogenous parenchyma, portal veins and hepatic veins
Can visualise the gallbladder
22
Q
What is the main differentiating feature between portal veins and hepatic veins on ultrasound?
A
Portal veins have hyperechoic walls whereas hepatic veins have hypoechoic walls
23
Q
Describe the normal anatomical appearance of the gallbladder on ultrasound
A
The gallbladder has a hyperechoic wall with anechoic contents
24
Q
What are the key signs of hepatomegaly on ultrasound?
A
Rounded margins
Projection beyond the costal arch
25
What are the key signs of microhepatica on ultrasound?
Liver deep within the costal arch
26
What is the key sign of liver hyperechogenicity on ultrasound?
Loss of clarity of the portal vessels indicates liver hyperechogenicity
27
Which differentials can be indicated by a hyperechoic liver on ultrasound?
Steroid hepatopathy
Chronic hepatitis
Hepatic lipidosis
Hepatic fibrosis
28
What are two possible causes of steroid hepatopathy?
Cushing's syndrome
Iatrogenic (drug-induced)
29
What is the key sign of liver hypoechogenicity on ultrasound?
Increased contrast between the parenchyma and the portal vessels indicates liver hypogenicity
30
Which differentials can be indicated by a hypoechoic liver on ultrasound?
Acute inflammation
Hepatic oedema
Hepatic lymphoma
Hepatic congestion
31
Identify this hepatic abnormality on ultrasound
Hyperechoic, heterogenous hepatic mass
32
Identify this hepatic abnormality on ultrasound
Hyperechoic, heterogenous hepatic mass
33
What are some of the differentials that can be indicated by a focal hepatic abnormality?
Neoplasia
Granulomas
Abscesses
Regenerative hyperplasia
Cysts
34
What is required for definitive diagnosis of a focal hepatic abnormality?
Fine needle aspirate (FNA)/biopsy
35
Which differentials should be considered when you see hepatic vascular abnormalities on ultrasound?
Hepatic venous congestion
Portosystemic shunt
36
What is the clinical significance of gallbladder sludge in dogs?
Gallbladder sludge in dogs is often an incidental finding
37
What is the clinical significance of gallbladder sludge in cats?
Gallbladder sludge in cats is more significant and can indicate cholestasis, cholangitis etc
38
What is a key sign of cholecystitis on ultrasound?
Gall bladder wall oedema/thickening
39
What is a gallbladder mucocoele?
A gallbladder mucocoele is gallbladder distension with accumulated mucoid secretions which may progress to semi-solid material
40
How can you differentiate between a mild and severe gallbladder mucocoele on ultrasound?
A mild gallbladder mucocoele is non-distinguishable from sludge however a severe gallbladder mucocoele has a striated appearance
41
Which dog breeds are particularly prone to gallbladder mucocoeles?
Border Terrier
Shetland Sheepdog
42
How do you treat a gallbladder mucocoele?
Some gallbadder mucocoeles can be treated medically however most gallbladder mucocoeles require surgical removal of the gallbladder as the mucus becomes adhered to the gallbladder wall
43
Which differentials can decrease serosal demarcation of the abdominal organs?
Decreased serosal fat
Increased soft tissue/fluid opacity
44
What can cause decreased serosal fat?
Young animals
Thin/emaciated patients
45
What can cause increased soft tissue/fluid opacity resulting in decreased serosal detailing?
Free fluid
Peritonitis
Carcinomatosis
Severe mesenteric lymphadenopathy
Abdominal masses
46
What are some normal anatomical change seen in obese cats on radiographs?
Bunching up of the intestines
Dorsal displacement of the liver due to excess falciform fat
47
Describe the normal anatomical appearance of the stomach on a radiograph
The size and content *(gas, fluid or ingesta)* of the stomach is variable and can even not be visible when empty
48
How is gas distributed within the stomach when the patient is in left lateral recumbency?
When the patient is in left lateral recumbency, gas in the stomach distributes to the antrum
49
How is gas distributed within the stomach when the patient is in right lateral recumbency?
When the patient is in right lateral recumbency, gas in the stomach distributes to the fundus
50
How can the appearance of the stomach change in dyspnoiec or aerophagic patients?
In dyspnoeic or aerophagic patients, the stomach can become gas filled
51
What is required to diagnose a gastric dilatation volvulus (GDV)?
To diagnose a gastric dilatation volvulus (GDV), there needs rotation of the antrum and duodenum into the dorsal portion of the abdomen
52
Which three factors should you assess when assessing the gastrointestinal tract on ultrasound?
Motility
Layering
Contents
53
How motile should a fasted gastrointestinal tract be?
A fasted gastrointestinal tract should have 1 to 2 movements per second
54
What are the different layers of the gastrointestinal tract that can be seen on ultrasound?
Serosa
Muscularis
Submucosa
Mucosa
Lumen
55
Which ultrasound view should you use to measure the wall thickness of the gastrointestinal tract?
You should measure the wall thickness of the gastrointestinal tract in long axis view
56
How thick should the wall of the canine stomach be on ultrasound?
3 - 5 mm
57
How thick should the wall of the feline stomach be on ultrasound?
1.1 - 3.6 mm
58
Why is it important to fast patients patients prior to an ultrasound of the stomach?
Ideally patients should be fasted prior to an ultrasound of the stomach as ingesta gas will result in acoustic shadowing which will obscure visualisation
59
How long should you fast a patient prior to an ultrasound of the stomach?
Fast the patient for 4 hours prior to the ultrasound
60
Describe the normal anatomical appearance of the stomach on ultrasound
The stomach will have a cartwheel appearance when empty due to the rugal folds and will often have a small amount of gas which will block the visualisation of part of the stomach wall due to acoustic shadowing. The stomach can vary in size and contents *(gas, fluid or ingesta)*
61
What can you do to get better visualisation of the stomach on ultrasound when there is gas in the lumen?
You can scan the patient standing or give them water to create an acoustic window which may improve visualisation
62
What are three common gastric lesions that can be seen on ultrasound?
Gastric ulcers
Gastric masses
Gastric outflow obstruction
63
What can gastric ulcers progress to?
Gastric ulcers can progress to gastric perforation
64
Describe the normal anatomical appearance of the small intestine on a radiograph
The small intestine is located in the mid abdomen and the content *(gas, fluid or both)* of the small intestine is variable, however the diameter of the loops of small intestine should be consistent
65
What is the normal diameter of the small intestine on a radiograph in dogs?
1 - 1.5 x height of the L5 vertebral body
66
What is the most common cause of intestinal dilation?
Obstruction
67
What is the normal diameter of the small intestine on a radiograph in cats?
12mm
68
Which species small intestine can appear bunched up on radiographs?
Cats
69
What are the key features of a small intestinal obstruction on radiography?
Dilation of the small intestinal loops
Foreign body may be visible
Colon may be empty and not visible *(if the patient has been obstructed for several days)*
70
Which imaging techniques can be useful when investigating a foreign body obstruction of the small intestine?
Take several radiograph views
Contrast radiography
Ultrasound
Negative contrast colography
71
What is negative contrast colography/pneumocologram?
Negative contrast colography/pneumocologram is a technique used to differentiate between the colon and small intestine when investigating a small intestinal mechanical obstruction, by introducing air into the colon via a rectally inserted urinary catheter to help visualise the colon
72
Identify the key features of this small intestinal obstruction
73
What is the key sign of ileus on radiography?
General dilation of the small intestine *(the whole small intestine will be dilated and there will be no normal small intestinal loops)*
74
What are four possible causes of ileus?
Gastric dilatation volvulus (GDV)
Peritonitis
Dysautonomia
Mechanical obstruction of the distal gastrointestinal tract
75
What are some of the potential signs of small intestinal neoplasia on radiography?
May be masses visible *(however these are often obscured by intestinal loops)*
Dilation of the small intestine
May be evidence of mechanical obstruction
## Footnote
Intestinal neoplasia can present similarly to mechanical obstruction on radiograph so if you have older patients with signs of obstruction on radiograph, you may want to do further investigation
76
Which imaging modality should you use to help diagnose small intestinal neoplasia?
Ultrasound
## Footnote
If you see signs of small intestinal obstruction in older patients, it is important to consider neoplasia and do an ultrasound
77
What are some key signs of gastrointestinal neoplasia on ultrasound?
Mass may be visible
Thickening of the wall layers
Loss of clearly defined wall layers
Irregular lumen
Signs of mechanical obstruction
78
What is the gravel sign on radiography?
The gravel sign is an accumulation of mineralised material directly above a partial, chronic, gastrointestinal mechanical obstruction
## Footnote
Be aware dogs fed raw food, bones etc can have normal digestion of mineralised material
79
Where should you place the ultrasound probe to assess the duodenum?
To assess the duodenum, place the ultrasound probe on the right flank
80
Identify the layers of the duodenum on this long axis ultrasound view
81
How thick should the wall of the feline duodenum be on ultrasound?
1.3 - 3.8mm
82
How thick should the wall of the canine duodenum be on ultrasound?
5.1 - 6mm
83
Where should you place the ultrasound probe to assess the jejunum?
To assess the jejunum, place the ultrasound probe on the mid abdomen
84
Identify the layers of the jejunum on this short axis ultrasound view
85
How thick should the wall of the canine jejunum be on ultrasound?
4.1 - 4.7mm
86
How thick should the wall of the feline jejunum be on ultrasound?
1.6 - 3.6mm
87
What is a distinguishing feature of the iluem when assessing the gastrointestinal tract on ultrasound?
The ileum has a prominent submucosal layer, differentiating it from the other regions of the gastrointestinal tract
88
What are some of the key signs of gastrointestinal mechanical obstruction on ultrasound?
- Distention proximal to the obstruction
- Stomach and intestine proximal to the obstruction can be fluid filled indicating outflow obstruction
- Intestinal walls are generally normal
- Foreign body may be identifiable
- Increased or absent gastrointestinal motility
89
How does a solid foreign body typically appear on ultrasound?
Often hyperechoic with strong acoustic shadowing, and the gastrointestinal tract will conform to the shape of the foreign body
90
What is a linear foreign body?
A linear foreign body describes long thin objects *(such as string etc)* which can become anchored under the tongue and swallowed into the gastrointestinal tract where the intestines can become bunched up around the linear foreign body
91
What are the risks of a linear foreign body?
Perforation
Peritonitis
92
What are the key signs of a linear foreign body on radiography?
Intestines appear bunched up with an undulating outline
'Comma shaped' gas bubbles
93
What are the key signs of a linear foreign body on ultrasound?
Intestinal plication
Foreign body material usually appears centrally
94
What is intestinal plication?
Intestinal plication refers to the folding of the intestinal wall
95
What is intussusception?
Intussusception is the invagaination of a portion of the intestine into the lumen of another
96
What is intussusception associated with?
Intussusception is associated with any gastrointestinal disease which causes hypermotility
97
What are the key signs of intussusception on ultrasound?
Intussusception has an 'onion-like' appearance on ultrasound due to the multiple layers of intestinal wall due to the telescoping of the intestine. Furthermore, there will be regions of mesenteric fat that have been pulled into the intestine
98
Which signalement is most prone to intussusception?
Typically younger animals are prone to intusussception due to hyperperiatalsis due to diarrhoea, however older animals can also present with intusussception
99
What are the key signs of enteritis on ultrasound?
Generally there will be no changes
Abnormal content in the lumen
Altered peristalsis
Increased gastrointestinal wall thickness
Increased mucosal echogenicity
Wall layering is typically normal
Intestinal corrugation
100
What is intestinal corrugation?
Intestinal corrugation refers to the wavy or ridged appearance of the muscularis, the serosa will remain smooth
101
What is typically indicated by intestinal corrugation?
Intestinal corrugation typically indicates inflammation however it is quite non-specific
102
Describe the normal anatomical appearance of the large intestine on radiography
The large intestine is located in the dorsal abdomen and the size and content *(gas, fluid or both)* of the large intestine is variable, it may not be visible when empty
103
What is the normal diameter of the large intestine on a radiograph in dogs?
Less than 1.5x the length of L7
104
What typically prevents full assessment of the colon on ultrasound?
Faeces cast an acoustic shadow and typically prevent full assessment of the colon on ultrasound
105
How thick should the wall of the canine colon be on ultrasound?
2 - 3mm
106
What can be done to allow for more accurate assessment of the colon?
Endoscopy can be done or an enema to remove the faeces from the colon followed by re-scanning with ultrasound
107
How thick should the wall of the feline colon be on ultrasound?
1.1 - 2.5mm
108
Which imaging modality is best for assessing the pancreas?
Ultrasound
109
What are the anatomical landmarks for the pancreas?
The left limb of the pancreas lies between the large curvature of the stomach and the transverse colon, the body of the pancreas lies at the pyloro-duodenal junction and the right limb of the pancreas runs along the duodenum
110
Describe the normal anatomical appearance of the pancreas on ultrasound
On ultrasound, the pancreas is hypoechoic and appears similar to fat, making it challenging to visualise. The pancreas should be equal to or smaller than the diameter of the duodenum
| Be aware the pancreas is challenging to visualise
111
What are the key signs of acute pancreatitis on ultrasound?
Decreased echogenicity of the pancreas (appears more hypoechoic) due to oedema
Pancreas has tiger striped appearance
Surrounding signs of pancreatitis *(hyperechoic hazy looking fat and free fluid)
112
Which disease can often look similar to pancreatitis?
Pancreatic neoplasia
