Diagnostic Imaging of Digestive Tract Flashcards
in what situations does serosal detail decreases (3)
- decreased fat (immaturity, emaciation)
- increased soft tissue opacity in/around mesentery (free fluids, peritonitis, carcinomatosis, severe mesenteric lymphadenopathy)
- large abdominal masses
what allows delineation of serosal margins of abdominal organs
mesenteric fat
what can increase serosal detail
pneumoperitoneum will increase clarity of serosal markings
around caudal margin of diaphragm
what would ddx be for increased serosal detail (3)
- recent surgery or abdominal penetration
- GIT perforation
- iatrogenic (ex. during pneumocystogram)
what is shown here

pneumoperitoneum
caudal margin of diaphragm
what is the normal appearance of the liver
even soft tissue opacity
triangular shape on lateral
what is the shape of the liver on lateral
triangular shape
sharp margin caudoventrally
extends to caudal aspect of costal arch
what is the gastric axis
used to assess the size of the liver
normal: parallel to ribs or perpindicular to spine

what is the appearance of the liver on VD
triangular, more to the right
tip is at the level of the costal arch
what are the signs of hepatomegaly
- caudal rotation of gastric axis
- liver extends caudally beyond costal arch
- rounding of caudal border
what is shown here

hepatomegaly
what is the ddx for hepatomegaly (4)
- hepatitis
- neoplasia
- cushings
- steroid use
what are the signs of microhepatica
- cranial rotation of gastric axis
- reduced size or herniation
what is shown here

microhepatica
what can be the ddx of microhepatica (2)
- portosystemic shunt (PSS)
- diaphragmatic rupture
identify the organs

red: stomach
pink: small intestine
orange: large intestine
can intestinal wall thickness be assessed on radiograph accurately
no
interfeace between gas the fluid –> wall is not actually thickened, it could be fluid that makes it look thickened

what is the appearance of the stomach on RLR
lying with right side down gas will collect in the fundus
left side of abdomen is highest

what is the appearance of the stomach on LLR
when dog is turned over the pylorus is the highest part of the stomach and gas will sit and give the stomach a dumbell appearance

what is shown here and what is the ddx

enlarged abnormal shape
GDV
what is the normal diameter of small intestine in canines
<1x height of lumbar vertabral body

what is the normal diameter of small intestine in felines
~<12mm
where are the small intestines located in the abdomen
generally ventral mid abdomen
what a small intestine obstruction appear on radiograph
single or few dilated or thickened loops
may be easier to see when gassy
foreign body may not be clearly seen
what is shown here

foreign body

what is ileus
general dilation of small intestine
what can cause ileus
- peritonitis
- GDV
- dysautonomia
how could you diagnose a small intestinal mass on rads (3)
may not be clear but
- diffuse mild thickening
- mass (obscured by other loops)
- evidence of obstruction
what is the gravel sign
collection of mineralized matieral immediately above partial GI obstruction
indicates chronic partial obstruction
must be persistent
what is shown here

gravel sign
partial pyloric outflow obstruction
where is the large intestine present
dorsal abdomen
what is the diameter of normal large intestine
<1.5x length of L7

what is shown here

large intestine
what is shown here

megacolon
dense radioopaque fecal material
twice length of L7
what can GI contrast studies be used to diagnose (3)
- identify obstruction
- assess mucosal surface (neoplasia, etc)
- intestinal function (transit times)
what is the diagnosis

serosal detail is very poor (skeletal mature –> free fluid)
distended intestinal loop that looks like there is fecal material to ventral to large colon –> has to be a distended small intestine
foriegn body in the small intestine
free gas –> perforated intestine and septic peritonitis
what are the pros of ultrasound (4)
- major diagnostic tool
- good for soft tissues (assess internal structure/parenchyma)
- safe, non-invasive, cheap, rapid
- real-time imaging (functional assessment –> cardiac, peristalsis, guidance for FNA/biopsy)
what are the cons of ultrasound (3)
- poor for bone and gas (lung, GI tract)
- need to clip hair
- operator (and machine) dependent
what is the ultrasound appearance of the normal liver
hypoechoic to spleen (slightly grainy texture)
vascular structures: hepatic viens and portal veins
gall bladder
sharp margins

where is the gall bladder on ultrasound
right to midline –> fluid filled, anaechoic
how is liver size assess on US
subjective
rads easier
does it extend too far caudally?
is liver too small?
what would diffuse hyperechoic changes in the liver be caused by (4)
- steroid hepatopathy including cushings
- chronic hepatitis
- fatty liver
- fibrosis
what would diffuse hypoechoic changes be due to (4)
- acute inflamamtion
- edema
- lymphoma
- congestion
what could focal abnormalities be due to in the liver (5)
- masses, cysts, etc
- neoplasia
- regenerative hyperplasia
- granulomas
- abscess
what vascular abnormalities can be seen on US in the liver
- venous congestion with right heart failure
- portosystemic shunts
what are billiary abnormalities seen on US (3)
- gall bladder sludge
- cholecystitis
- biliary obstruction
what are the layers of the GI tract (5)
- serosa
- muscularis
- submucosa
- mucosa
- lumen
what is the approx thickness of the stomach in the long axis US view in dogs
3-5mm
what is the approx thickness of the stomach in the long axis US view in cats
1.1-3.6mm
what is the approx thickness of the duodenum in the long axis US view in dogs
5.1-6.0mm
what is the approx thickness of the duodenum in the long axis US view in cats
1.3-3.8mm
what is the approx thickness of the jejunum in the long axis US view in dogs
4.1-4.7mm
what is the approx thickness of the jejunum in the long axis US view in cats
1.6-3.6mm
what is the approx thickness of the colon in the long axis US view in dogs
2.0-3.0mm
what is the approx thickness of the colon in the long axis US view in cats
1.1-2.5mm
what does the stomach look like on long axis view US
kiwi fruit appearance

where can the duodenum be scanned
right dorsal flank
what is the duodenum a landmark for on US
pancreas and pylorus
what is the appearance of the duodenum on US
coffee bean appearance

where is the jejunum scanned
mid abdomen
what is the appearance of the ileum on US
prominent submucosal layer
where is the ileo-cecal junction
right mid abdomen
what is the approx wall thickness of the colon on US
2-3mm
what does an US GI tract assessment include (5)
- function
- obstruction (intussusceptions, contents, foreign material)
- wall thickness and layers
- neoplasia
- enteritis
how can a GIT obstruction be seen on US
distention proximal and empty distal (two populations)
what is seen here

distended and fluid filled
obstruction
how are solid foreign materials seen on US
often hyperechoic + shadowing
distinct shape
GIT conforms to shape
how are linear foreign bodies seen on US
short angular turns
bunching of SI
what is shown here

foreign material in SI
peach stem
what is shown here

linear foreign body
string
what is the appearance of an intussusception on US
mutliple wall layers
hyperechoic mesenteric fat
what is shown here

intussusception
what is the appearance of neoplasia on the GI tract (6)
- loss of wall layers
- markedly thickened walls
- irregular lumen
- lack of peristalsis
- focal vs. generalized
- continuity with adjacent GI tract
what changes can be subjectively seen with enteritis on US (5)
- abnormal content
- altered peristalsis
- increased wall thickness
- increased mucosal echogenicity
- irregular lumenal interface
what is shown here

neoplasia
what is seen here

free fluid around intestinal loops
enteritis
what are the landmarks for the pancreas on US (3)
- stomach
- transverse colon
- spleen
what are the differences in the left and right limbs of the pancreas
left limb is bigger in cats and smaller in dogs
right limb is bigger in dogs and smaller in cats
what is shown here

left limb of pancreas

what is the landmark of the right limb of the pancreas
duodenum
what is the appearance of the right limb of pancreas
similar/hypoechoic to surrounding fat
may not be visible
what is shown here

right limb of pancreas

what is shown here

right limb of pancreas
how does pancreatitis change the appearance on US
- edematous (hyperechoic)
- surrounding peritonitis and free fluid
how does pancreatic neoplasia change the appearance on US (2)
- mass/nodule
- may appear similar to pancreatitis
what is shown here

pancreatitis
edematous
surroudning peritonitis and free fluid
what is shown here

pancreatic neoplasia