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Abdominal Imaging 1

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sihirlifil's version from 2017-10-28 19:20

Intro & Fluid

Question Answer
What are the normal abdominal regions on the lateral view? VD?Lat: 1) Craniodorsal 2) Cranioventral 3) Midabdomen 4) Caudodorsal 5) Caudoventral
VD: 1) L cranial 2) R cranial 3) Mid-abdomen 4) Caudal
Normal anatomy: arrows pointing at?
Maroon: gastric fundus
Light blue: R kidney (esp in fat dog)
Dark blue: L kidney
Yellow: colon (gas & feces ~1/3 up the abd)
White: urinary bladder (can see if full of urine)
Orange: givaway :) (tend to move if mass)
Lavender: Spleen (more reliably seen RRL)
Black: liver
Red: pylorus
(Can also ID cecum, intra-abd prostate)
How are things arranged on VD view?Liver intercostal, peaks either side
Stomach caudal to liver (gas in it)
Gastrosplenic ligament soft tissue triangle
Transverse colon immediately caudal to somach
Good serosal detail means?Well defined organ margins (perceive eternal surfaces of structures within the abdomen)
Poor serosal detail means?Organ margins obscured by presence of fluid/not well defined
What is the difference between these 2 projections?
Left: Good serosal detail!
Right: Decreased serosal detail. Can only really ID gas in the intestines
What influences serosal detail?Difference in opacity between 1 organ and another
Amout of intra-abd fat present (falciform, retroperitoneal, mesenteric & omental)
Content of abdominal organs e.g. gas
Left image: arrows pointing at (3)? Right image (1)?
Left: Fat in falciform ligament (bottom left), retroperitoneal fat (top blue), mesenteric fat (bottom right)
RightL Mesenteric fat
T/F the spleen is easier to ID in a cat than a dogFalse. unusual to see spleen in cat
NORMAL: arrows pointing at?
Liver (left) and spleen (right)
(image slightly underexposed, also was EXPIRATORY study which we don’t want)
NORMAL: arrows pointing at?
Large fat deposits in very… well-endowed… cat
NORMAL: 8-wk-old puppy. How is the serosal detail? why?
Poor serosal detail due to brown fat in young animals having relatively high fluid content
As animal grows and develops white fat, serosal detail improves. Can start to differentiate spleen, bladder, etc
(look at the growh plates :))
NORMAL: Greyhound. How is the serosal detail?
POOR! Very little fat to create contrast
NORMAL: what’s going on with this cat? (hint: arrow)
Ate like 2 cans of food before radiographs. Can see granular material in stomach
What’s going on here (Arrow)?
whopping Right cranioventral midabdominal ST mass from T11-L4
Lose serosal detail
Possible types of peritoneal fluidBlood
Urine
Bile
Transudate
Exudate (peritonitis, e.g. FB perforation)
How do we get a definitive dx of peritoneal fluid?Cytological analysis TAP TAP TAP! ABDOMINOCENTESIS NECESSARY
Can ID presence of fluid with imaging, but not the type
How does peritoneal fluid look on radiographs?Poor abdominal contrast: border effacement of liver, spleen, bladder
Serosal detail indistinct
May be localized or generalized
Homogenous ST opacity throughout abdomen
Intestinal gas shadows lie in center of adb (floating)
Penulous abd wall margins
Abdominal free fluid in a cat
Problem? Top arrow pointing at?
Abdominal fluid
Arrow = kidney! So retroperitoneal space is normal
What’s wrong here? (also look at spine!)
HBC dog --> peritoneal fluid could be hemorrhage or any other fluid type (in this case ruptured bladder)
Fracture of L6!
Imaging method of choice for peritoneal fluid =Ultrasonography
Small volumes of fluid can be identified
Guided aspiration of fluid from specific site is possible
Peritoneal fluid US: transducer type? Positioning?3.5–7.5MHz depending on size; up to 10MHz for small
Lat/Dors recumbency, or standing if necessary
How does peritoneal fluid look on US?Anechoic outlines around serosal surfaces if no cells/protein
Swirling/snowy appearance if chronic due to cells/protein (e.g. FIP)
Fibrin tags can be IDd (look like moving seaweed fronds)
What kind of fluid is this?
Transudate Anechoic = no fluid or cells
Which kind of fluid at arrow?
Cellular Echogenic, snowy (can see kidney, intestine loops also)
Causes of peritoneal fluidNeoplasia: Carcinomatosis, mesothelioma
Peritoneal seeding: Splenic neoplasia
Pancreatitis: local inflammation (focal loss of serosal detail)
Free urine or bile in abd
Intestinal perforation
Which is worse, free urine or bile?BILE --> chemical peritonitis
Bile peritonitis may bce caused by?Trauma or result of chronic obstruction to outflow into duodenum
2 types of peritonitisSeptic or aseptic (can’t tell diff with imaging. must tap!!!)
How does peritonitis look on radiographs?Ground glass appearance (granular/patchy increase in opacity)
Generalized poor serosal detail (e.g. bladder or GB rupture); usually localized with intestinal perforation or pancreatitis (b/c mesentery contains infection, but still become generalized when chronic)
+/- free abd air (perforated ulcer/intestine/body wall)
Static of intestinal contents (regional ileus at site of perforation) & buildup proximal
Arrows?
Ground glass = lack of serosal in cranioventral abdomen due to pancreatitis
Can see both kidneys in retroperitoneal space, colon, bladder; poor detail everywhere else
With pancreatitis, loss of serosal detail is usually where?Cranioventral and Right cranial
How does pancreatitis look on US?Regional ileus in proximal duodenum (local inflammation)
Hypo/anechoid fluid around duodenum (R cranioventral)
Swollen pancreatic tissue (medial to duodenum)
Signs of abscessation, swelling, +/- mass
Causes of uroperitoneum: rupture of what 3 things?Bladder
Ureters within peritoneal cavity (proximal part is retroperitoneal)
Urethra
How’s the serosal detail?
Generalized widespread lack, due to ruptured bladder
(negative contrast in bladder CONTRAINDICATED if suspect rupture! soapbox)
This positive contrast regrograd cystogram demonstrates?
Bladder rupture contrast introduced through urethra, leaked into abdominal cavity (arrow)
Better diagnositc method for uroperitoneum?Positive contrast radiography
For bladder rupture, pos contrast cystography reliable for dx rupture (abdominocentesis & fluid analysis too)
Blank arrows?
Echogenic fluid in case of uroperitoneum (snowstorm effect)
How does the bladder look?
Small with thickened wall; could be misdiagnosed as cystitis, or just an empty bladder (wall is thicker when empty)
How does peritonitis look on US?May be localized or generalized
Fluid usually echogenic
Large number of oscillating fibrin tags
Adhesions between organs or intestines (esp chronic), ileus of adjacent intestines
May see hyperechoic gas bubbles
If you’re gonna do abdcentesis and US, which first? why?ALWAYS US BEFORE ABDOMINOCENTESIS
Centesis introduces air into abd cavity, whcich can be misinterpreted as focal hyperechoic gas bubbles of peritonitis (false pos)
Causes of perionteal hemorrhageRuptured spleen/liver
Avulsed blood vessel
Erosion of vial structure by neoplasm
Peritoneal hemorrhage
Highly echogenic patchy fluid/material, and clots
Fluid at left arrow compared to right?
L: echogenic fluid
R: Less echoic, fluid-filled intestines
How does a retroperitoneal mass appear on radiographs?Mass effect in dorsal abdomen
Ventral displacement of abdominal structures (or to side)
Displacement of kidneys
How do you identify a ruptured kidney, ureter or vessel?IV positive contrast!
Arrows pointing to? What’s going on?
Retroperitoneal ST masses Arrows = Colon (displaced ventrally)
Lack of renal definition (can see L, not R)
Renal rupture (avulsed R side: urine & blood)
How is US used for retroperitoneal mass/fluid?Helps ddx mass from fluid (can be difficult to ddx from intra-abd fluid, esp if large volume of asictes)
US-guided aspiration & FNA
Causes of intra-abdominal air/gasDirect perforating abdominal injury
GI perforation/rupture
Post pneumocystography in animal with bladder rupture/iatrogenic (overenthusiastic catheterization)
Post laparotomy/coeliotomy most common
How does intra-abdomina air/gas look on radiographs?Serosal surfaces (liver, diaphragm) outlined by gas opacity
Gas rises, seen under right costal arch (use horizontal beam with animal in LLR)
Unusualy gas patterns (bubbles, streaks) not associated with lumen of GI tract
Intra-abdominal air in cat
Air surrounds kidneys, cd L diaphragmatic crus
Why is the patient positioned like this?
LEFT lateral recumbent (decbitus) view using horizontal beam, with cassette along dorsum
LLR to keep fundus out of the way! (Gas in funus = can’t outline intra-abd gas as well as it rises)
Used in cases where free intra-abd gas suspected and requires confirmation
Gas under costal arch = free air
Dog was in LLR ~10 min, using horizontal beam. Good to pick up small volumes of air
Can we use US for intra-abd air?Difficult to appreciate… scan upper/non-dependent region, may see reflective hyperechoic area
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