Download cross-sectional-anatomy-liver-part-1

HHHoldorf
 Portal
Vein: Collects blood from the
digestive tract and empties into the liver
and is formed by the junction of the
splenic vein and the superior mesenteric
vein. A large left branch supplies the left
lobe of the liver. The right portal vein has a
major branch coming off just superior to
the
gallbladder.
Portal
veins
have
echogenic borders and branch away from
the porta hepatic.
 Portal
veins have echogenic borders
 Portal veins converge at the portal hepatis
 Portal veins demonstrate hepato-petal blood
flow
 Hepatic Veins do not have echogenic borders
 Hepatic Veins converge at the IVC
 Hepatic Veins demonstrate hepto-fugal blood
flow.
 Main
lobar fissure: Fissure between the
right and left lobes of the liver: seen only
between the gallbladder and the right
portal vein.
 Ligamentum
Teres: Echogenic structure in
the left lobe of the liver (a remnant of the
ductus venosum) in which the umbilical
vein runs.
 Ligamentum
venosum: Echogenic line
anterior to the caudate lobe of the liver.
 The
ligamentum teres represents the
inferior end of the separation between the
medical and laterals segments of the left
lobe.
 A.K.A. The Round Ligament
 The
round ligament represents the
remnant of the fetal umbilical vein. For a
month or two after birth, the umbilical
vein is patent, subsequently degenerating
to fibrous tissue, the round ligament.
 Define

Ligamentum Venosus
Draw a cartoon of fetal circulation as it relates
to the liver
 Define
Riedel’s lobe
 Porta
Hepatis: Echogenic region
surrounding the portal veins, hepatic
artery, and common bile duct where all
these structures enter the liver.
 The
hepatic veins represent the divisions
between the lobes and segments of the
liver. The middle hepatic vein divides the
right and left lobes of the liver. The left
hepatic vein separates the medical and
lateral segments of the left lobe: the right
hepatic vein separates the anterior and
posterior segments of the right lobe of the
liver.
 The
gallbladder represents the inferior end
of the separation between right and left
lobes of the liver.
 Technique
A
real-time scanner with a small foot print
and a wide field of view is generally the
preferred equipment. This enables easy sub
costal and intercostal scanning. As the liver
is a large organ, the optimal transducer
should provide focusing from near to far
field.
 The
patient is generally placed in the supine
or left lateral decubitus position. The
transducer is placed in a sub costal location.
Intercostal scanning may be necessary if the
patient is too full of gas or if the liver is
small and too high for adequate sub costal
scanning. Scans are generally done in
longitudinal, transverse, and oblique planes.
The best images of the diaphragmatic portion
of the liver are usually obtained from a sub
costal location with deep, suspended
inspirations.
 Fasting?
Check departmental protocols.
 The
liver is located in the upper abdomen
adjacent to the diaphragm. The bulk of the
liver is located in the RUQ and in most
patients part of the left love extends into
the LUQ. The liver is displaced inferiorly with
inspiration. Except for several ligament
attachments, there is a large potential space
for the accumulation of fluids between the
liver and diaphragm known as the right and
left subphrenic or sub-diaphragmatic spaces.
 The
normal liver should have a homogenous
parenchymal echo texture. The normal echo
brightness should be equal or slightly greater
than the renal cortex and slightly less than
the spleen.
 The
size and shape of the normal liver is
quite variable making it difficult to assess
with real-time scanning whether it is of
appropriate size, too small (atrophic), or too
large (Hepatomegaly). In the right midclavicular line, the cranio-caudal dimension
of the normal adult liver should be in the
range or 10.5 cm (+/- 1.5 cm) with 13 cm
considered a highly reliable cut-off for
normal livers. An explanation should be
sought if it measures more or less than this.
 The
surface of the liver is smooth and
covered by a fibrous capsule known as
Glisson’s capsule. Trauma to the liver
without laceration to Glisson’s capsule may
be seen as a localized subcapsular fluid
collection. The liver is impressed by the right
kidney, gallbladder, colon and stomach. The
actual position of these organs relative to
the liver is quite variable. For example: the
right kidney may be positioned high and be
completely draped anteriorly by liver or it
may be low an only be partially covered by
liver.
 The
major hepatic and portal veins should be
easily seen in the normal liver. The hepatic
veins are most prominent closest to the
diaphragm. The right, middle, and left
Hepatic Veins converge to enter the IVC. The
Hepatic Veins have thin, smooth walls which
only produce a bright echo when the sound
beam is perpendicular to the vessel surface.
Portal Veins are largest near the porta
hepatis and decrease in size as they
subdivide and extend toward the periphery.
Each PV courses with a fibrous channel with
a hepatic artery and bile duct.
KEY POINTS
 Collectively,
three vessels from the PORTAL
TRIAD: Hepatic Artery, Biliary Radical, and
Portal Vein.
 A fibrous channel accounts for the thick
bright wall seen around the PV.
 The HVs and PVs are both affected by
respiration although the affect is most
pronounced in the HVs.