Transcript Distinguishing Characteristics of Hepatic and Portal Veins

Abdominal Imaging of
Liver
Dr Mohamed El Safwany , MD.
Intended Learning Outcomes
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The student should be able at the end of the
lecture to recognize ultrasound principles of
the liver
Anatomy
 Protocols
 Normal Ultrasound
Findings
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Anatomy of the Liver
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The Liver occupies all of the
right hypochondrium, the
greater part of the epigastrium,
and left hypochondrium. The
ribs cover the greater part of the
right lobe .In the epigastric
region, the liver extends several
centimeters below the xiphoid
process. Most of the left lobe of
the liver is covered by the rib
cage.
Lobes of the Liver
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Right lobe: The right lobe of the liver is the largest
of the liver’s lobes. It occupies the right
hypochodrium.
Left lobe: The left lobe of the liver lies in the
epigastric and left hypochondriac region.
Caudate lobe: The caudate lobe is a small lobe
situated on the posterosuperior surface of the left
lobe opposite the tenth and eleventh thoracic
vertebrae .
Hepatic Nomenclature
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Couinaud’s system of hepatic
nomenclature provides the anatomic basis
for hepatic surgical resection. By using this
system , the radiologist may be able to
precisely isolate the location of a lesion for
the surgical team
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Couinaud’s hepatic segments divide the liver
into eight segments . The hepatic veins are the
longitudinal boundaries . The transverse plane
is defined by the right and left portal pedicles .
Hepatic Segmental Anatomy
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The caudate lobe (segmentⅠ) is
situated posteriorly.
Segment Ⅰincludes the caudate
lobe.
Segment Ⅱand Ⅲ includes the
left superior and inferior lateral
segment.
Segment Ⅳa and Ⅳb includes
the medial segment of the left
lobe.
SegmentⅤ and Ⅵ are caudal to
the transverse plane .
Segments Ⅶ and Ⅷ are
cephalad to the transverse plane.
Vascular Supply: Portal vein
The portal venous
system is a reliable
indicator of various
ultrasonic tomographic
planes throughout the
liver.
80% of vascular supply
Main portal vein
Right main portal vein
Left main portal vein
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Hepatic artery : branch of abdominal aorta
Enters liver through porta hepatis
20%of arterial supply to liver
Divides in the liver into right and left branches
Hepatic veins
The hepatic veins are divided into three
components: right,middle,and left.
Distinguishing Characteristics of Hepatic
and Portal Veins
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The best way to distinguish
the hepatic from the portal
vessels is to trace their
points of entry to the liver.
The hepatic vessels flow into
the inferior vena cava,
whereas the splenic veins
and superior mesenteric vein
join together to form the
portal venous system.
Distinguishing Characteristics of Hepatic
and Portal Veins
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The walls of hepatic veins are thin-walled ,and the walls
of portal veins are brightly reflective veins
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The hepatic veins are easily differentiated from
bile ducts and portal veins .
They are not surrounded by an echogenic wall
They originate close to the diaphragm , and can
be traced into the inferior vena cava
Sonographic Evaluation of the Liver
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Evaluation of the hepatic structure is one of
the most important procedures in sonography
for many reasons. The normal , basiclly
homogenerous parenchyma of the liver
allows imaging of the neighboring anatomic
structures in the upper abdomen.
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The appropriate transducer depends
on the patient’s body habitus and size
The average adult abdomen usually
requires a 3.5MHz
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The basic instrumentation should be adjusted
in the following parameters :
Time gain compensation
Overall gain
Transducer frequency and type
Depth and focus
Sagittal image of gallbladder
Gallbladder and Biliary System
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Normal size of
gallbladder:
7~9cm in length ;
3~4cm in width;
Wall thickness : 2~3mm
Normal size of bile ducts :
right /left intrahepatic
duct just to proximal
CHD: 2-3mm ；
CBD:≥8mm =dilated
Sagittal image of liver /right kidney
The normal liver parenchyma should have a
softer , more homogenerous texture than the
dense medulla and hypoechoic renal cortex
Transverse Scan Plane
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Multiple transverse scans are made across the upper
abdomen to record specific areas of the liver. The
transducer should be angled in a steep cephalic
direction to be as parallel to the diaphragm as possible.
Transverse Scan Plane
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The transducer is then directed slightly inferior to
record the left portal vein as it flows into the left
lobe of the liver.
The gallbladder may be seen in this scan as an
anechoic structure medial to the right lobe and
anterior to the right kidney.
Common bile duct
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Diameter <0.8cm
Sonographic Evaluation of The Liver
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Adequate scanning technique demands that
each patient be examined with the following
assessment
The size of the liver in the longitudinal plane
The attenuation of the liver parenchyma
Liver texture
The presence of hepatic vascular structures,
ligaments ,and fissures
Pathology of the Liver
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Evaluation of the liver parenchyma
includes the assessment of its size ,
configuration, homogeneity , and contour.
The Normal attenuation of the liver parenchyma
Normal: Liver texture=homogeneous
Assessment of its size , configuration, homogeneity ,
and contour
Suggested Readings
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David Sutton’s Radiology
Assignment
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Two students will be selected for assignment
Question
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Describe the vascular supply of the liver.
Thank you for your attention!