Small animal abdomen radiographs Flashcards
Effacement/silhouetting
Allows you to tell apart different structures if they have different opacities or if there is something else in between them
Abdomen image optimization
-Abdomen has low intrinsic contrast (fat in mesentery/omentum surrounding soft tissue visceral organs)
*low kVp and high mAs= narrow scale of grey to exaggerates intrinsic contrast
Thoracic image optimization
high kVp, low mAs
Standard views of abdominal radiographs
At least 2 views, but commonly 3 views
-left lateral, right lateral, VD
Size of abdominal radiographs
Few cm cranial to diaphragm to few cm caudal to the coxofemoral joints
*large dogs may need 2 images per view
Positioning tips for the abdomen
-keep pelvic limbs relaxed allowing expansion of abdominal cavity and prevent skin folds
-take exposure at end expiration to allow expansion of abdominal cavity and reduce organ crowding
How to tell if radiographs are straight
Lateral views- check transverse processes for check marks
VD views- spinous processes should be end on
Systemic approach to interpretation of abdominal rads (example)
Normal abdominal organ visibility
Organs that are not normally visible in abdominal radiographs
Peritoneal organs
Anything covered by visceral peritoneum
-liver
-gallbladder
-spleen
-pancreas
-GIT
-mesenteric lymph nodes
-blood vessels
Retroperitoneal organs
Organs only partially covered by visceral peritoneal
-kidneys
-ureters
-adrenal glands
-blood vessels
-aortic lymph nodes
**communicates with mediastinum through aortic hiatus
Serosal detail or contrast
The ability to see the margins of abdominal organs
-often occurs because the present of fat in the peritoneal and retroperitoneal space
*will be altered when other opacity enters the areas= decreased with fluid or increased with gas
Decreased in serosal detail
-Lack of intraabdominal fat (emaciated or young animals)
-presence of brown fat in young animals (higher water content)
-superimposed external material (debris, wet hair, US gel)
-underexposure
-diseases (eg. ureter rupture=fluid accumulation)
Increase in serosal detail
-due to free gas within the peritoneal/retroperitoneal space = pneumoperitoneum/pneumoretroperitoneum
-pathological
-post-operative (can be up to around 3 wks, volume should gradually decrease over time)
Identifying pneumoperitoneum
Use horizontal beam
-free gas will collect in the highest point of the abdomen
-look under the ribs on a horizontal beam VD and look under the xyphoid on a horizontal beam lateral view
GI tract abdominal view
Pylorus differences between cats and dogs
Rugal folds
Folds within the fundus area
-can see them when gas is present
Fat opacity within feline gastric wall
Normal fat deposits in cats
Types of gastric appearance
-Depends on content
Purpose of the 2 lateral views for stomach
- Fundus in left dorsal abdomen
- Pylorus= right ventral abdomen
*Gravity effects gas and fluid
-left lateral=fluid fills fundus, gas fills pylorus
-right lateral= fluid fills the pylorus, gas fills fundus
Duodenum
-fairly consistent position along right side of abdomen
-diameter sometimes larger than jejunum
Parts of the duodenum
- duodenum bulb/cranial duodenal flexure
- descending duodenum
- caudal duodenal flexure
- ascending duodenum
Canine peyer’s patches
Normal finding (often young dogs)
-lymphoid aggregates alone the anti-mesenteric border of the GI
*dont mistake for ulcers
String of pearls presence in cats
Normal peristalsis present in feline small intestines
Small intestinal distribution in fat cats
Commonly see small intestines centralized in one area due to presence of fat
Small intestinal luminal gas
-Normal
-typically more in dogs than cats
-post-prandial GIT tends to contain more gas
-distressed or dyspneic patient can have more gas due to aerophagia
Large intestine components
-cecum (often seen in dogs, but not cats)
-colon (ascending, transverse, descending)
-rectum
Cecum in dogs
-distinct
-right cranial to mid abdomen
-blind ended, coiled, gas filled
Cat cecum
-less developed than dogs
-no cecocolic sphincter
-rarely seen as small blind pouch
Normal intestinal diameters
- small intestines
-dogs= less than 1.6x height of L5 on lateral
-cats= less than 12mm on lateral - Colon
-no reference value for dogs
-cats= less than 1.28x L5 length on lateral
Can you measure GI wall thickness on radiographs?
No, wall thickness and fluid around will appear the same and make it seem thicker
Contrast studies
- positive contrast (barium)= increased opacity compared to GI
- Negative contrast (Gas)= agents more lucent than normal GI
When are contrast studies used?
-esophagraphy
-gastrography
-upper GI studies
-Colonography
**location of bowel, GI transit times, ID obstruction, mucosal interface lesions, abnormal luminal content
Contraindications for contrast studies
-when lesion visible on normal radiographs
-when GIT perforation is suspected
Small intestines ultrasound
*mucosa is the thickest
Pancreas
-normally not seen on radiographs; except left lobe sometimes seen in cats
Pancreas
-difficult to see because no capsule
Liver
Liver on radiographs
-lies between diaphragm and stomach
-homogeneous soft tissues
-sharp triangle within costochondral arches; assess liver size based on position of stomach
Feline liver
-consistent size
-large fat opacity ventral to liver showing sharp margin along border
-will also sit more towards the right side than dogs
What species is which?
Gastric axis
Used to determine liver size
-normal range between perpendicular to vertebral column to the parallel intercostal spaces
Liver on ultrasound
-course texture
-portal veins with hyperechoic walls
-hepatic veins
Gallbladder
-right cranial abdomen
-seen in cats rarely
Gallbladder on radiographs
-located right of midline
-homogenous fluid opaque
-often not visible because liver covers it
*exception= cats- it can protrude slightly beyond liver border on lateral view
Gallbladder on ultrasound
-contained anechoic bile
-thin walled
-surrounded by liver parenchyma
Canine spleen
-head of spleen is fixed to dorsal left abdomen by the gastrosplenic ligament
-tail of the spleen is moveable and can fold on itself
Splenomegaly
Feline spleen
-thinner and smaller than dogs
-splenic tail less variable in location= often sits along left abdomen
**should not be seen on lateral rad
Spleen on ultrasound
-fine echotexture
-splenic veins at hilus
-more echogenic than liver
Kidneys
-Left kidney is lagging (caudal)
-cranial pole of Right kidney effaces with Right liver
Normal Renal length
Measured on VD projection
Dog: 2.5-3.5 xL2 length
Cat: 2-3 x L2 length
Fat opacity in cat kidney
-radiolucent fat in renal hilus
*normal finding
Kidneys on ultrasounds
-smooth margination
-well defined corticomedullary distinction (medulla more hypoechoic than cortex)
-collapsed renal pelvis without fluid dilation
Ureters
-not visible on radiographs or US when normal
What is this nodular like structure?
Often mistaken for ureters with stone present
**But not stones, these are just vessels
Excretory urography
Positive iodine contrast given IV
-used to visualize urinary structures that are normally not seen
-evaluate kidney function
Contraindications for excretory urography
-dehydration
-hypotension
-renal failure
-known hypersensitivity to contrast (because can lead to swelling, hives, nausea)
Normal phases of excretory urogram
- Vascular phase
- Nephrogram phase
- Pyelogram
Vascular phase
5-7s after injection, hard to capture
-see renal arteries
Nephrogram phase
10s to 2 mins after injection
-renal parenchyma, cortex first than medulla
Pyelogram phase
Last a variable amount of time and allows you to see renal perfusion, GFR, hydration status. patency of urinary system
Normal excretory urogram
Urinary bladder and urethra
-visibility depends on size
-urethra normally not visible unless using special procedure (retrograde cystourethrogram)
Urinary bladder on ultrasound
-anechoic urine
-wall thickness varies with distension but should always be smooth
Retrograde cystourethrogram
Positive contrasts (iodine) given retrograde via urethra
-used to located lower urinary tract, check for leakage/rupture, intraluminal and intramural disease
Complications from retrograde cystourethrogram
-iatrogenic trauma to lover urinary tract from catheter
-knotting of urinary catheter within bladder
-rare- gas embolized in vascular system= pulmonary embolism
Retrograde cystourethrogram
Flexed hip (butt shot) radiographs
-used in male dog to evaluate the penile urethra
Pitfalls of male dogs
-nipples on prepuce
-secondary ossification of the os penis
Pitfall for male cats
Mineralized os penis
-do not mistake for a urolith/calculi
Prostate
Visibility depends on reproductive status
-large and more visible in intact male (benign hyperplasia)
-atrophied and not visible in neutered dogs unless diseased
-not visible in cats
Prostate
Prostate on ultrasound
-small in neutered males
-large, bilobed, symmetrical, smooth margination in intact males
Uterus
Visibility depends on reproductive status
-not seen in spayed or anestrus animals
-more visible with distension (preg, disease)
Pregnancy on radiographs
Can be seen after fetal mineralization
Dogs= 43 days
Cats= 38days
Distended uterus= Tubular structure in caudal peritoneum coursing between colon and urinary bladder
Uterus on ultrasound
Mickey mouse sign=distended uterus
