abdomen Flashcards
EFFACEMENT/ SILHOUETTING
- We can only tell the margins of two contacting structures apart if they are of different opacities, or if they are spaced apart by a different opacity in between
- If two structures of the same opacity are contacting, we can no longer tell their margins apart
image optimization of the abdomen
- kVp = the energy of the X-ray photons
- mAs = the amount of X-ray photons
- The thorax has high intrinsic contrast
- Abdomen has low intrinsic contrast (fat in mesentery/ omentum surrounding soft tissue visceral organs)
- Uses a lower kVp and higher mAs – show narrow scale of grey,
thus able to exaggerate the intrinsic contrast of abdominal content
STANDARD VIEWS FOR ABDOMINAL
RADIOGRAPHS
- At least two views, but commonly perform three views as a standard practice
- Left lateral
- Right lateral
- Ventrodorsal
- Include the entire abdomen
- Few cm cranial to the diaphragam to few cm caudal to the coxofemoral joints**
- Large dogs may need two images per view
positioning tips for abdominal rads
- Keep the pelvic limbs relax to allow expansion of abdominal cavity and prevent skin folds (frog leg in VD view)
- Take exposure at end expiration to allow expansion
of abdominal cavity and reduce organ crowding
how to tell if you took straight/ proper ab rads
how to interpret rads
- first step Are the radiographs diagnostic?
* Views
* Positioning
* Technique - then Systematic approach (adopt a search pattern) same everytime
normally visible structures on ab rads
NORMALLY NOT VISIBLE on ab rads
adrenals
pancrease
GB
uteters
lymph nodes
uterus
decrease in serosal detail causes
increase in serosal detail causes
HORIZONTAL BEAM RADIOGRAPHY
CAN HELP TO IDENTIFY
PNEUMOPERITONEUM
the purpose of two lateral views
- To help us evaluate different
parts of the stomach - Fundus sits in the left dorsal
abdomen - Pylorus sites in the right ventral
abdomen - Gravity effects gas and fluid
distribution in the gastric
lumen**
o On left lateral view, fluid fills the
fundus, and gas fills the pylorus
o On right lateral view, fluid fills the
pylorus, and gas fills the fundus **
L vs right lateral views for evaluating the pylorus
On RL the pyloris is fluid filled
On LL the pyloris is full of air
ORMAL CANINE DUODENAL PEYER’S
PATCHES (“PSEUDOULCERS”)
normal feline intestinal appearance
SI distribution in fat cats
-the intestines look gathered which is normal
cecum dogs
-distinct cecum more than cats
-right cranial to mid abdomen
-blind ended coiled, gas filled commonly
normal intestine diameter
-measured serosa to serosa
- Small intestines
o Dogs: <1.6 times L5 height (at
mid body) on lateral radiographs
o Cats: <12mm; or <2 times L2
endplate height on lateral
radiographs - Colon
o Cats: <1.28 times L5 length on
lateral radiographs
DO NOT MEASURE GI WALL
THICKNESS ON RADIOGRAPHS!
contrast studies
-always normal rads first
-Positive contrast: agents more opaque than normal GI content (Barium, iodine)
- Negative contrast: agents more lucent than normal GI content (Room air, CO2)
- Types of studies:
- Esophagraphy
- Gastrography
- Upper GI study (for small intestines)
- Colonography
indications and contraindications for contrast studies
- Indications:
- To determine location of the bowel
- To evaluate gastrointestinal motility (GI transit time)
- To identify obstruction, abnormal luminal content, or mucosal interface lesions
- Contraindications:
- When lesion is visible on plain radiographs
- When GIT perforation is suspected
liver on rads
- Lies between the diaphragm (cranially) and
stomach (caudally) - Homogeneously soft tissue opaque
- Assessment of liver size best made by noting the
position of the stomach (“gastric axis”) - Caudoventral liver margin should be a sharp
triangle, without extend much beyond the
costochondral arches on the lateral view
-can change with different canine body conformation
species differences: On VD view, cat liver sits more towards the right side than in dogs
dog liver
normal feline liver
gastric axis
-line along long axis of the stomach, should be paralelle or close to that to the ribs
gastric axis shifted caudally
hepatomegaly
liver is round, and extends past the ribs
gastric axis cranially
microhepatia (small liver)
-hard to see triagnl liver shape margination and cranial deviation
canine spleen
feline spleen
kidneys
- L Kidney is left behind (caudal)
- Cranial pole of R kidney effaces with
R liver (renal fossa of caudate lobe)
-normal fat opacity in feline renal plevis/ hilus (radiolucent fat opaque area in renal hilus)
normal renal length dogs and cats
ureters
-not normally seen
-sometimes able to see opaque nodule like structures in plane of LV by l5/l6 which is the end on circumfluence iliac vessels not ureter or stones
EXCRETORY UROGRAPHY
-positive contrast administered IV (iodine) NOT barium.
-* Indications:
* To visualize urinary structures that are normally not visible (renal
pelvis, ureters)
* Can indirectly evaluate renal function
- Risks:
- Uncommonly may have immediate adverse reactions to iodinated contrast (eg. Nausea, hives
Contraindications:
* Dehydration, hypotension, anuric renal failure, known hypersensitivity to contrast
RETROGRADE
(VAGINO)CYSTOURETHROGRAM
- Imaging studies after a positive contrast agent is administered retrograde via the urethra
-use IODINE only - Indications:
- To locate the lower urinary tract
- To look for leakage/ rupture
- Evaluate intraluminal and intramural diseases
- Potential complications:
- Iatrogenic trauma
additional view for male dog urethra
-dogs nipples are seen by prepuce
-prepuce is secondary ossification center usually at proximal end of os penis (not a stone or fracture)
mineralized os penis in cats
prostate
double bubble appearance, prostate is 2nd bubble, bladder is 1st
distended uterus
