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Abdominal Imaging 2

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sihirlifil's version from 2017-11-02 20:08

Liver

Question Answer
Which part of the liver is visible?Caudo-ventral margin
Location is inferred byAssessing position of the gastric axis (too far cranial = small liver, vice versa)
How does the liver look on lateral view?Triangular area between diaphragm & ventral body wall, falciform ligament, & stomach
Almost entirely within costal arch
Sharp outline
+/- Mild extension beyond costal arch
Arrows show?
Normal gastric axis (usually parallel to 10th ICS/rib)
NORMAL: line going where?
Gastric axis: line from fundus through body to pylorus. ALMOST VERTICAL!
Can see liver within costal arch ventrally
How does the gastric axis vary between breeds?
Describe US techniqueClip widely! (warn owners)
Probe at xiphyisternum
Angle cranio-dorsally
Fan from left to right to image entire liver; trace in long plane (nose to tail long axis)
IF SMALL LIVER: need to scan intercostally
What are the planes of scan?
Top arrow showing? Bottom?
Top: moderately echogenic with granular appearance
Bottom: Portal vessels hyperechoic parallel lines
Lobes are smooth in outline, sharply pointed
T/F The hepatic arteries are hyperintense on USFALSE! Can't see hepatic arteries!
How should the liver lobes look?
Sharp, not rounded
Shouldn't extend further caudal than costal arch
How does the gall bladder look?Anechoic, rounded or pear-shaped
Where can you see the common bile duct on US in a dog?YOU CAN'T!
On a sagittal sonogram of the abdomen, which tissue is anechoic? Hyperechoic?Gall bladder hypoechoic (contains bile)
SPLEEN = hyperechoic

(D = diaphragm)
Arrows? (transverse US of NORMAL liver)
Left: Hepatic veins (NOT ARTERIES!) hypoechoic, walls not visible
Right: Portal vessles with hyperechoic walls
US: Assess the liver for overallSize
Echogenicity
Changes in contour & architecture
Biliary abnormalities
What is the mirror image artifact? What does it tell us?Light hits curved surface, reflected sound from particular wave goes back to transducer, machine calculated how long it took to get back, overcorrects and puts it on the OTHER SIDE of the diaphragm
Tells us diaphragm is intact
What's going on here?
Mirror image artifact
Machine puts gall bladder on other side of diaphragm
What's this again?
Acoustic enhancement between small arrows (not as much absorbed coming through tissues)
More echogenic = DEFINTELY fluid, probably gall bladder. If 4, 5, 6 etc: hepatic cysts
Is this normal?
Hepatomegaly
Gastric axis displaced caudally and left. Not parallel with ribs or perpendicular to spine
Something on R side pushing everything to left
Is this normal?
Hepatomegaly with caudal displacement of gastric axis (small arrow) & poor serosal detail in cranioventral abdomen (long arrow)
Liver mass with local peritoneal seeding
Is this normal
MILD hepatomegaly: this is an INSPIRATORY image, so the projection of liver (arrow) is not as bad as it seems!
Is this normal?
Hepatomegaly: rounded edges of margin and lies beyond costal arch
Echogenicity of the liver: types (4)Diffuse/Multifocal hypoechoic/hyperechoic
Echogenicity?
Diffuse hyperechoic
Echogenicity?
Diffuse hypoechoic
Possible causes of diffusely hypoechoic liverLymphoma
Congestion
Acute hepatitis (Lepto)
Possible causes of diffusely hyperechoic liverHAC (↑ glycogen in hepatocytes bc stimulates gluconeogenesis)
Hypothyroidism
Non-specific hepatopathies
Fatty infiltration
IF SMALL LIVER: can be fibrosis (cirrhosis)
(rarely lymphoma)
If you see round hypoechoic spots, what are you thinking?May be masses but could be NORMAL! Need FNA to work out cause
Multifocal nodules look (3)Hypoechoic
Hyperechoic
Mixed
Arrows?
Nodule off tip of lobe, surrounded ominously by large body of fluid (probably transudate)
How does this mass look?
Deforming the normal sharp liver edge
(L = liver, f = fluid, g = gall bladder)
Heterogenicity of mass suggests malignancy
How are the echogenicities of these nodules?
Left arrow: Hyopechoic
Right arrow: Anechoic
Lower: fluid & tissue
(ideally needle each one)
Possible causes of liver nodulesBenign nodular hyperplasia
Primary liver neoplasia
Metastatic nodule
Hematomas
What's going on?
Benign nodular hyperplasia
Not all nodules or margin irregularities are associated with neoplasia or cirrhosis; FNA and biopsy required

(BNH in spleen: looks worse than it is)
Liver neoplasia
Arrows
Multiple hypoechoic nodules in liver neoplasia
Metastatic neoplasia
CLASSIC Target lesion
Is this normal?
Microhepatica: portocaval anomaly
Gastric axis displaced CRANIALLY
Cirrhosis = small nodular liver (usually end-stage))
Arrows?
Cirrhosis
Anechoic fluid surrounds irregular lobes
Normal fetal and adult portal system:Fetus: umbilical vein (u) perfuses liver, most of volume diverted through ductus venosus (d) to fetal heart. u & d atrophy soon after birth, then portal vein blood (p) perfuses hepatic sinusoids completely and collected by hepatic veins
Patent ductus venosus (d) +/- hypoplastic portal system
Intrahepatic PSS
Portal vein atresia, associated with development of multiple portopostcaval anastomoses
Major solitary portopostcaval anastomosis
Most common
Isolated, major portal azygous shunt
Dx with US
Portal azygous shunt with discontinuation of prerenal segment of CVC
Is this normal?
Microhepatica from PSS
Liver well within costal arch, stomach axis displaced cranially
(Sagittal sonogram CFD) Arrow?
Ascites in near field surrounding intestines
Blue = CVC
Red = Aorta
Portal vein missing (often find between CVC & Ao)
(Sagittal image) Turbulence = ?
Anomalous vessel exiting portal vein in PSS
CAn see entry into CVC
((CA = celiac artery, CMA = cr mesenteric a.
(Sagittal image) Turbulence = ?
PSS: Vessel entering CVC
This mesenteric portography is showing? (which type?)
PSS
Positive contrast injected into jejunal vessel (mesenteric vein), contrast bypasses liver & passes through PDV into CVC
Intrahepatic PSS
Is this cat's gall bladder normal?
YES! Bilobed often seen. Normal variation
Biliary abnormalities (5)Sludge: sand, sediment move to dependent side (pic)
Calculi
Inc/Dec thickness (should be no more than 2mm)
Cystic mucinous hyperplasia (can't dx on US)
GB mucocoele
Marked distention of common bile duct. Should run straight line to duodenum
Pancreatic disease (neoplasia, infection) or bile duct carcinoma (d = bile duct)
NOT CYSTS!
Long arrow? short?
Long: Cholelith
Short: ACOUSTIC SHADOW!
memorize

Spleen

Question Answer
Where is the spleen located?L cranial abdomen
Approx parallel to greater curvature of stomach
How is the head attached to the stomach?Gastrosplenic ligament
What are these images demonstrating? (Top RLR, bottom LLR)
More consistently seen in Right lateral view
Left lateral view: may or may not be seen
Why is hx of sedation important?Certain anesthetic agents can cause splenomegaly (barbiturates)
Which breed tends to have big spleen?GSD (can go all the way to bladder!)
Can you usually see the spleen on a cat?No
Arrow pointing at what part?
Tail of the spleen (flips upward)
Arrow pointing at what part?
Head of spleen
Lateral to fundus of stomach, curls along abd wall
Difference between these 2 images?
Top: can see triangular ST opacity on left side, cd & lat to stomach, cr to left kidney
Bottom: Cat thinner and smaller. Can only see because it’s outlined by fat
Arrows? whats going on?
Splenomegaly Arrows = head & tail
May be physological (sedation) or pathological
Arrow? whats going on?
Splenomegaly Arrow = TAIL of spleen, extending along floor of abdomen
Pathological causes of splenomegalyAnemia
Neoplasia
Hematomas
Cysts/abscesses
Association w/ GDV
Splenomegaly due to neoplasia or huge hematoma
Large ST mass in mid-ventral abdomen. High potential for rupture (better out than in)
On US, how should the spleen look compared to the liver and kidneys?Spleen should be hyperechoic
How is the splenic echotexture on US?Hyperechoic, densely packed tissue, granular, can see blood vessels
Describe the mass
Hypoechoic in tail of spleen (+ splenomegaly)
Could be tumor, hyperplasia, hematoma…
Describe the mass
Mixed echogenic = more likely to be neoplastic
memorize

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