The document summarizes the normal radiological anatomy and segmentation of the liver. It describes: - The liver can be divided into three lobes: right, left, and caudate. The right lobe is separated from the left by Cantlie's line, which contains the middle hepatic vein. - Couinaud classification divides the liver into eight segments based on vascular inflow and outflow. Each segment has its own branch of the portal vein, hepatic artery and bile duct. - Common pathologies seen on imaging include cirrhosis, cysts, abscesses, hemangiomas, focal nodular hyperplasia, and hepatocellular carcinoma.

1. RADIOLOGICAL ANAOMY OF
LIVER

2. Functionally, can be divided into three lobes: right, left, and caudate.
The right lobe of the liver is separated from the left by the main lobar fissure,
which passes through the gallbladder fossa to the inferior vena cava (IVC).
middle hepatic vein lies in the main lobar fissure, this vertical plane runs
from the inferior vena cava to the gallbladder fossa and is also known as
Cantlie's line(not visible on surface).
The right lobe of the liver can be further divided into anterior and
posterior segments by the right intersegmental fissure.
The left intersegmental fissure divides the left lobe into medial and lateral
segments.
The caudate lobe is situated on the posterior aspect of the liver, with the IVC as
its posterior border and the fissure for the ligamentum venosum as its anterior
border.
NORMAL ANATOMY OF LIVER

9. The major hepatic veins course between the lobes and segments (interlobar
and intersegmental).
The middle hepatic vein courses within the main lobar fissure and separates
the anterior segment of the right lobe from the medial segment of the left.
The right hepatic vein runs within the right intersegmental fissure and divides
the right lobe into anterior and posterior segments.
The major branches of the right and left portal veins run centrally within the
segments (intrasegmental), with the exception of the ascending portion of the
left portal vein, which runs in the left intersegmental fissure.
The left intersegmental fissure, which separates the medial segment of the left
lobe from the lateral segment, can be divided into cranial, middle, and caudal
sections.
The left hepatic vein forms the boundary of the cranial third, the ascending
branch of the left portal vein represents the middle third, and the fissure for
the ligamentum teres acts as the most caudal division of the left lobe.

10. Couinaud classification
It divides the liver into eight functionally independent segments.
Each segment has its own vascular inflow, outflow and biliary drainage.
In the centre of each segment there is a branch of the portal vein, hepatic
artery and bile duct.
In the periphery of each segment there is vascular outflow through the
hepatic veins.
Right hepatic vein divides the right lobe into anterior and posterior
segments.
Middle hepatic vein divides the liver into right and left lobes (or right and
left hemi liver). This plane runs from the inferior vena cava to the gallbladder
fossa.
The Falciform ligament divides the left lobe into a medial- segment IV and
a lateral part - segment II and III.
The portal vein divides the liver into upper and lower segments.
The left and right portal veins branch superiorly and inferiorly to project into
the centre of each segment.
SEGMENTAL
ANATOMY

12. Couinaud’ssegments

22. Couinaud divided the liver into a
functional left and right liver by a
main portal scissurae containing the
middle hepatic vein.
This is known as Cantlie's line.
Cantlie's line runs from the middle of
the gallbladder fossa anteriorly to the
inferior vena cava posteriorly.
This figure is a transverse image
through the superior liver segments,
that are divided by the right and
middle hepatic veins and the
falciform ligament.

23. This is a transverse image at the level of
the left portal vein.
At this level the left portal vein divides the
left lobe into the superior segments (II
and IVa) and the inferior segments (III
and IVb).
The left portal vein is at a higher level than
the right portal vein
This image is at the level of the right
portal vein.
At this level the right portal vein divides
the right lobe of the liver into superior
segments (VII and VIII) and the
inferior segments (V and VI).
The level of the right portal vein is
inferior to the level of the left portal
vein.

24. At the level of the splenic vein, which
is below the level of the right portal
vein, only the inferior segments are
visible

27. Normal Liver Size and Echogenicity
The upper border of the liver lies approximately at the level of the fifth
intercostal space at the midclavicular line. The lower border extends to
or slightly below the costal margin.
liver length of greater than 15.5 cm, hepatomegaly is present. The organ
size increases with height and body surface area and decreases with age.
The mean longitudinal diameter of the liver in the midclavicular line in this
study was 10.5 cm, with standard deviation (SD) of 1.5 cm, and the mean
midclavicular anteroposterior diameter was 8.1 cm (SD 1.9 cm).
Riedel lobe is a tongue like extension of the inferior tip of the right lobe of
the liver, frequently found in asthenic women.
The normal liver is homogeneous, contains fine-level echoes, and is either
minimally hyperechoic or isoechoic compared to the normal renal cortex

28. Cross-
Section
Imaging

29. How to separate liver segments
on cross sectional imaging
Left lobe: lateral(II/III) vs
medial segment (IVA/B)
Extrapolate a line along the falciform
ligament superiorly to the confluence
of the left and middle hepatic veins at
the IVC (blue line).
Left vs Right lobe: IVA/B vs
V/VIII
Extrapolate a line from the
gallbladder fossa superiorly along the
middle hepatic vein to the IVC (red
line).
Right lobe: anterior (V/VIII) vs
posterior segment (VI/VII)
Extrapolate a line along the right
hepatic vein from the IVC inferiorly to
the lateral liver margin (green line).

30. AXIAL SECTIONS ON CT SCAN

33. CORONAL SECTIONS

35. SAGITTAL SECTIONS

38. COMMON PATHOLOGIES IN
LIVER

39. Cirrhotic liver
Liver cirrhosis is the result of chronic liver disease. Causing
irreversible damage to the liver tissue. The liver is small and
proportions have changed; the left liver lobe and segment 1 are
hypertrophic, and the right liver lobe is atrophic. The liver tissue and
surface has a nodular aspect . Liver cirrhosis may increase the
pressure in the hepatic vessels, giving rise to ‘portal hypertension’.
Signs of portal hypertension include collateral formation,
splenomegaly and ascites.
Cyst
Cysts are very common abnormalities in the liver. A liver cyst may
vary in size from a few millimeters up to more than 10 cm. Cysts are
sharply delineated with a low density (HU < 10). Cysts do not
enhance

42. Abscess
Abscesses in the liver are
usually a complication of
an intestinal infection.
The bacteria migrate to
the liver through the
venous system. Patients
with a liver abscess are
sick, have a fever and
elevated infection
parameters in the blood.
The abscess is usually a
cluster of jaggedly
delineated hypodensities.
The abscess rim may
enhance

43. Focal nodular hyperplasia
Focal nodular hyperplasia (FNH) is more common in women than men. FNH arises
from liver cells and bile duct cells. FNH is sharply delineated and hypervascular.
Characteristic of FNH is the star-shaped fibrous core in the middle of the tumor, the
so-called central scar . In most FNHs, the fibrous central scar enhances in the
equilibrium/delayed phase.

44. Focal nodular hyperplasia with a nearly isoechoic mass
with spokewheel vascularity

45. Hemangioma
Hemangiomas are common
abnormalities in the liver. A
hemangioma can be up to 10
cm in size. Hemangiomas are
sharply delineated with a
specific enhancement
pattern. The arterial phase
reveals peripheral, nodular,
discontinuous enhancement
and the portal venous phase
reveals progressive filling

47. Adenoma
Adenomas are particularly
common in women aged 20-50
years, but may also occur in men.
Oral contraceptive use constitutes
a risk factor for developing an
adenoma. Large adenomas may
bleed or become malignant. Sizes
vary markedly: from 1 cm up to
more than 20 cm. Adenomas are
hypervascular, usually clearly
delineated, encapsulated and may
contain fat. The bleedings and
presence of fat may give the
adenoma a heterogeneous aspect .
The enhancement pattern varies.
About 20% have enhancement of
the (pseudo)capsule in the
equilibrium/delayed phase.

48. Hydatid cysts result from infection by the Echinococcus tapeworm species The cysts
usually have three components 1,2:
pericyst: composed of inflammatory tissue of host origin
exocyst
endocyst: scolices (the larval stage of the parasite) and the laminated membrane are
produced here

50. Hepatocellular carcinoma in a patient with liver cirrhosis

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