2. ANATOMY
The liver is the largest solid organ in the normal abdomen,
occupying much of the right upper quadrant.
The liver is divided into eight functional segments based on
vascular and biliary anatomy.
3.
The middle hepatic vein marks the division between the right
and left hemiliver.
The right hepatic vein divides the right hemiliver into an
anterior and posterior section.
The left hepatic vein divides the left hemiliver into a medial
and lateral section.
Hepatic veins separate the hepatic segments, major portal
vein run through the middle of the segments
4. Hepatomegaly (>17 cm) are extension of the right lobe below
the lower pole of the kidney, rounding of the inferior tip of
the liver, and extension of the left lobe into the left upper
quadrant above the spleen.
The liver parenchyma is normally homogeneous and is
interrupted only by the portal triads and hepatic veins.
Echogenicity of the liver should be slightly greater than or
equal to that of the right kidney but less than that of the
spleen. The liver is usually less echogenic than pancreas.
6. The middle and left hepatic veins usually join together just
before entering the inferior vena cava (IVC).
Smaller, dorsal hepatic veins from the posterior right lobe and
the caudate lobe often drain into the vena cava below the
level of the three main veins.
7. Normal liver anatomy.
A, Transverse view of the hepatic vein confluence shows the
right (R), middle (M), and left (L) hepatic veins.
The segments of the liver are also shown. The superior left
hemiliver includes segments 2 and 4A and the right hemiliver
includes segments 7 and 8.
Two portal vein branches (P) in the right anterior segment differ
from the hepatic veins by the echogenic fibrofatty tissue
surrounding the vessel.
8.
9.
10.
11. B, Transverse view at the level of the umbilical portion of the
left portal vein (U) shows the fissure for the ligamentum
venosum (FL) separating segment 1 (the caudate lobe) and the
left lateral section (LL).
The fissure for the ligamentum venosum connects to the
umbilical portion of the left portal vein. The inferior vena cava
(VC) is also seen.
12.
13.
14. C, Transverse view just inferior to B shows the ligamentum
teres (LT) immediately below the anterior aspect of the
umbilical segment of the left portal vein. The interlobar
fissure (IF) is seen posteriorly.
Segments 3 and 4B are separated by the LT. Segments 5 and 6
are posterior to the IF.
15.
16. D, Transverse view just inferior to C shows the gallbladder (GB)
immediately below the IF. The IF (interlobar fissure) and the
GB fossa separate segments 4B and 5. The LT separates
segments 3 and 4B. A gallstone is present in the gallbladder.
E, Longitudinal view from the midline of the abdomen shows the
fissure for the ligamentum venosum (FL), which separates
segment 1 from segments 2 and 3.
17.
18. F, Longitudinal view through the left lobe shows the umbilical
segment of the left portal vein (U) and the LT.
Note that the LT connects to the anterior most aspect of the
umbilical segment of the left portal vein.
The remnant of the umbilical vein is seen as a hypoechoic band in
the middle of the otherwise fat-containing ligament.
19.
20. Normal hepatic artery anatomy.
Both views of the normal celiac axis show the celiac artery (C)
arising from the aorta (A). On the transverse view the
common hepatic artery (H) is seen traveling anterior to the
portal vein (P). The splenic artery (SP) and inferior vena cava
(V) are also seen.
On longitudinal view, the superior mesenteric artery (S), left
renal vein (LRV), pancreas (P), distal esophagus (E), and the
crus of the diaphragm (D) are also seen.
21.
22.
23.
24.
25.
26. Hepatic artery variants. Longitudinal (A) and transverse (B)
views of a replaced left hepatic artery (arrows). On the
longitudinal
view, the artery is seen as a small round dot within the echogenic
linear fissure for the ligamentum venosum. Transverse (C) and
longitudinal
27. (D) views of a replaced right hepatic (RH) artery. On the
transverse view, the replaced RH artery is seen arising from the
superior mesenteric artery (S). Also seen is the aorta (A), vena
cava (V), left renal vein (RV), and portal vein (P). The longitudinal
view shows the replaced RH artery posterior to the portal vein
and the proper hepatic artery (PH) anterior to the portal vein.
E, Transverse view shows the right (R) and left (L) hepatic arteries
arising as separate vessels from the celiac artery (C). The aorta
(A) and vena cava (V) are also seen.
28. F, Transverse view shows the hepatic artery (H) and the splenic
artery (S) arising as separate branches from the aorta (A). In
this case the hepatic artery is passing behind the portal vein
(P). The vena cava (V) is also seen.
29. Diaphragmatic fissures. A common variation that is seen in the
periphery of the liver is deep fissures caused by hypertrophied
diaphragmatic muscle bundles.
A, Two adjacent echogenic triangular-shaped defects are
identified on the surface of the liver. These represent two
external fissures caused by the diaphragm (D).
B, View 90 degrees of A shows, these two defects as an elongated
band of diaphragmatic muscle external to the liver.
30. TECHNIQUE
The liver is usually best scanned with a sector or a curved Array
transducer. Linear-array transducers of even higher frequencies
are useful for imaging superficial abnormalities.
The left hemiliver can be imaged effectively in most patients from an
anterior subxiphoid approach. Right hemiliver should be scanned
from both subcostal and intercostal approaches
31. Intercostal scans are most effective with the patient in supine
position and provide best results during normal respiration
when the right lung base and its associated shadowing are not
obscuring the superior aspects of the liver.
Rib shadowing can be minimized by imaging in an oblique plane that
is parallel to the long axis of the intercostal spaces.
32. Subcostal scanning should be performed with the patient in
a left lateral decubitus or left posterior oblique position so
that the liver shifts slightly medial and inferior.
angle the transducer superiorly while scanning from a subcostal
approach so that the dome of the liver can be visualized.
33. 1. CYSTS
Simple hepatic cysts are the most common focal liver lesion.
Because the liver is such a homogeneous organ, cysts are
usually easy to detect.
Fig., A, Hepatic cyst shows classic findings and obvious
increased through transmission
34. B, Hepatic cyst shows peripheral puckering, which is
frequently seen in otherwise simple hepatic cysts.
(C), Transverse sonogram show a subcentimeter hepatic cyst
(arrow). Despite its small size, the cyst is anechoic with a
well-defined back wall
35. Complex cystic lesions are most often due to hemorrhage they
have internal echoes, a thick wall, septations that are
numerous or thick, solid elements, or calcification.
Hemorrhagic cysts:
A, Cyst with fluid cellular layer (cursors). B, Cyst with
solid retracting internal clot (cursors).
36. C, Cyst with multiple internal membranes and solid mural
thrombus (cursors).
D, Cyst with diffuse low-level echoes (cursors) and obvious
through transmission.
37. Vascular lesions such as aneurysms, can simulate cysts on
grayscale sonography but are easily distinguished with
Doppler analysis. Pseudoaneurysm simulating a hepatic cyst.
A, Gray-scale view of the liver shows an anechoic structure
(cursors) with a welldefined back wall and increased through
transmission. This has a typical appearance of a hepatic cyst.
B, Doppler analysis shows swirling flow throughout the lesion,
consistent with a pseudoaneurysm.
38. 2. BENIGN TUMORS
Hemangiomas are the most common benign liver neoplasm, found
more often in women than in men. Structurally, they are much
like a sponge filled with blood. Multiple, small, blood-filled
spaces are separated by fibrous septations. The typical
appearance is a homogeneous, hyperechoic mass that is usually
less than 3 cm in size.
39.
40. Fig., A and B, Typical homogeneous, hyperechoic, well-defined
masses (cursors). C, Lesion with isoechoic center and a thick
peripheral hyperechoic halo.
41. Focal nodular hyperplasia (FNH) is a benign tumor of the liver
FNHs are isoechoic or nearly isoechoic to liver parenchyma
42. Hepatic Adenoma
Simple, small uncomplicated adenomas tend to be homogeneous and
are often hypoechoic. Internal hemorrhage or necrosis usually
produces a heterogeneous appearance and/or complex cystic
components.
A, Solid, hypoechoic mass. B, Two homogeneous, hyperechoic
masses. C, Heterogeneous mass with both hypoechoic and
hyperechoic components
43.
44. MALIGNANT TUMORS
Metastases: The majority of metastatic lesions have a target
appearance with an echogenic or isoechoic center and a
hypoechoic halo.
Fig., Target lesions secondary to hepatic metastases in
different patients. The central aspect of the tumor ranges
from isoechoic to hyperechoic and the hypoechoic halo ranges
from thick to thin
45.
46. Hepatocellular Carcinoma: it may be solitary, multifocal, or
diffuse and infiltrating. It is a large dominant lesion with
scattered smaller satellite lesions. Echogenicity is also variable
and are hypervascular.
Fig.,Standard (A) and high-resolution (B) views of the liver show
a solid, homogeneous, hypoechoic lesion and a diffusely nodular
liver parenchyma. C, Slightly hyperechoic target lesion.
47.
48. Lymphoma is a very homogeneous tumor, it may generate few
internal reflections. It is typically hypoechoic. In rare
instances, it can appear anechoic and simulate a cyst. It may
also have some detectable posterior enhancement.
Fig., A, Multiple homogeneous, hypoechoic, solid liver lesions. B,
Classic target lesions.
49.
50. INFECTIONS
Hepatic abscesses typically appear as complex fluid collections
with a mixed echogenicity, as thick-walled cystic lesions or
as cysts with fluid–fluid levels.
A, Complex cystic lesion with multiple locules typical of a
hepatic abscess.
B, Irregular cystic lesion with a thick nodular wall.
C, Hypoechoic lesion with cystic and solid elements
51.
52. DIFFUSE PARENCHYMAL DISEASE
Hepatitis usually results in no detectable sonographic
abnormality.
In a limited number of patients it can cause increased
echogenicity of the portal triads, which appear as small bright
areas on views of the liver periphery.
This appearance has been referred to as the starry sky sign.
Unfortunately, it can be seen in the absence of hepatitis, and
when present, it is often subtle. Hepatitis can also produce
marked thickening of the gallbladder wall, contraction of the
gallbladder lumen.
53.
54. Hepatitis. A, Transverse view through the mid aspect of
the liver shows multiple portal triads that stand out because
of their unusually echogenic borders.
B, Longitudinal view of the gallbladder shows a thick wall
and a contracted lumen.
C, Longitudinal view of the porta hepatis shows multiple
prominent periportal lymph nodes (asterisks).
A
55. Cirrhosis
Cirrhosis is caused by hepatocellular death and resulting
fibrosis and regeneration. It occurs most commonly due to
alcohol abuse, which causes micronodular changes (<1 cm in
size). Hepatitis is the next most common cause and results
in macronodular cirrhosis (size of nodules between 1 and
5 cm). Surface nodularity is a sonographic sign of cirrhosis.
When there is only a trace amount of perihepatic ascites, it
is important to avoid heavy pressure with the transducer
because it can displace the ascites away from the liver
surface.
56.
57. Cirrhosis in different patients. Standard view (A) and high-
resolution views with normal transducer pressure (B) and with
minimal transducer pressure (C). Parenchymal coarsening is
questionable on the standard view but is easily seen on the
high-resolution views.
With minimal transducer pressure, a trace amount of ascites
flows over the liver surface allowing excellent visualization of
surface nodularity.
