Abdominal Radiographs Flashcards
what are the standard projections for abdominal radiographs
right lateral
ventrodorsal
what provides contrast to see the outlines of organs within the abdominal cavity
fat (fat in omentum and falciform ligament)
what provides contrast to see the outlines of things within the GI tract
gas
what machine settings are best for abdominal radiographs
low kVp and high mAs
summation
overlapping structures with a different opacity in between makes the area brighter
silhouette
overlapping structures of same opacity makes the margins indistinct
(ex fluid in the abdomen)
what are the boundaries of the abdomen
- diaphragm (cranial border)
- spinal (dorsal border)
- body wall (ventral border)
which crus of the diaphragm is more cranial in right lateral
right crus
which crus of the diaphragm is more caudal in right lateral
left crus
what is the normal appearance of the ventral body wall
extends from liver to pubis in a shallow convexity
deep chest: may appear concave
overweight: may appear distended
peritoneal detail
the visibility of serous surfaces of organs
- surrounded by fat, should normally have distinct margins
what view is best for evaluating peritoneal detail
lateral because the animal is at its thinnest
what does good peritoneal detail mean
sharp/clear serosal margins
what does increased peritoneal detail mean
air in the peritoneum
(pneumoperitoneum)
what does poor peritoneal detail mean
- young (normal)
- thin (normal)
- diseased (abnormal)
categories of poor detail
- focal
- mottled
- generalized/diffuse
focal area of poor detail
- mass
- focal peritonitis
- small effusion
mottled area of poor detail
- severe peritonitis
- carcinomatosis
generalized/diffuse area of poor detail
- effusion
- young/thin
types of effusion
transudate
exudate
blood
urine
(all appear soft tissue opaque)
how to diagnose free air in the abdomen
positional radiographs
- upright and cross table studies
- expect gas to rise to right underneath diaphragm in upright
- expect gas to rise to under the ribs in cross table
what side of the patient is the fundus on
left side; located in left crus of diaphragm
large compartment
where is the body of the stomach
across/intersecting the spine
more dorsally located
what side of the patient is the pylorus on
right side; located more ventrally
small compartment
how to localize stomach in radiographs
take multiple positions to see where the gas moves
will move to the highest compartment in the stomach
where does gas move in left lateral
pylorus
where does gas move in right lateral
fundus
where does gas move in dv
fundus
where does gas move in vd
body
causes of gastric enlargement
- gas
- fluid
- food
gastric dilation
enlarged, gas filled stomach in normal position
may extend past ribs - use location of fundus/pylorus
gastric torsion
enlarged, gas filled stomach in abnormal position
how to ID gastric torsion on radiographs
right lateral: gas will go to pylorus and pylorus will be dorsal to fundus
vd: pylorus will be on the left
soft tissue shelf
soft tissue shelf
ST opaque line between fundus and pylorus that indicates GDV
gastric obstruction
fluid filled stomach
- difficult to locate stomach/indistinct margins
- enlarged, fluid opaque stomach with small gas bubble inside
what is the normal diameter of a small intestine
less than two ribs OR height of vertebral body
should be uniform across all loops
categories of small intestine obstruction
- generalized
- focal intraluminal
- intramural
generalized SI obstruction
uniform enlargement along entire SI tract
indicates functional obstruction (enteritis)
focal intraluminal SI obstruction
areas of distention upstream of obstruction with normal areas downstream
indicates mechanical obstruction (foreign body)
linear foreign bodies
strings, socks, etc
causes plication of SI along the object (U turn bulges of the SI)
may see crescent shaped gas bubbles
left lateral: gas and ST opacity in pylorus
intramural SI obstruction
obstruction originating from the wall of the SI that causes narrowing of the lumen
causes gravel sign
gravel sign
particles accumulate in narrowed lumen where they are unable to pass –> creates mineral intensity in SI
how can you determine if an obstruction is acute or chronic
degree of dilation
smaller = acute
larger = chronic
how to locate colon on radiographs
trace backward from pelvis
may contain gas, fluid or feces
descending colon may shift to right (normal)
colon obstruction
enlargement of the colon
functional obstruction most common
mechanical obstruction unlikely due to ability to reach colon - can usually pass
where is the liver located
most cranial organ in abdomen
borders:
1. diaphragm (cranial)
2. falciform fat (ventral)
3. stomach (caudal)
criteria for determining normal liver size
- should not extend beyond costal arch
- margins should be sharp
- normal distance between stomach and liver
- gastric axis should be at a normal angle (slight caudal)
hepatomegaly
enlargement of the liver; alters some or all 4 size criteria
- liver extends beyond costal arch
- rounded margins
- large distance between stomach and liver (caudal displacement of stomach)
- caudally angled gastric axis
what direction does enlarged liver push the stomach
caudal
fundus is attached to gastrosplenic ligament; body/pylorus rest on the liver
focal enlargement of the liver
masses, granulomas, abscesses, cysts
changes the normal contour of the liver
- pushes on the stomach –> abnormal curvature but NOT displaced
when is hepatomegaly normal
young animals
(larger liver size in proportion to their bodies)
microhepatica
small liver
causes cranial displacement of the stomach/gastric axis
when is micro-hepatica normal
cats (smaller liver in proportion to falciform fat)
deep chested dogs
biliary mineralization
tree shaped mineral opacities within the liver
choleliths
stones in the gallbladder
appear as circular mineral opacity in RIGHT VENTRAL part of liver
localizing the spleen on radiographs
dogs: proximal and distal part
(proximal is caudal to fundus; distal is mobile)
cats: proximal part only
normal spleen appearance
sharp margins
triangular
splenomegaly
generalized enlargement of the spleen
- rounded margins
- retains triangular shape
confirm with vd
focal enlargement of the spleen
distorts the contour of the spleen
- rounded margins
- loss of triangular shape (becomes rounded)
splenic masses
displace the kidneys and stomach
- kidneys: caudal
- stomach: mass effect; pushes stomach cranially
can cause effusion –> poor peritoneal detail
normal pancreas on radiographs
not visible
body is located in gastroduodenal angle (between pylorus, duodenum, and transverse colon)
enlarged pancreas
only visible if severe enlargement
- focal poor peritoneal detail in cranial abdomen (gastroduodenal angle)
- may see mass effect
- widens gastroduodenal angle
