Diagnostic ultrasound ( PDFDrive )

CHAPTER 4 The Liver 75
The liver is the largest organ in the human body, weighing
approximately 1500 g in the adult. Because it is frequently
involved in systemic and local disease, sonographic examination
is oten requested to assess hepatic abnormality.
SONOGRAPHIC TECHNIQUE
he liver is best examined with real-time sonography. Both supine
and right anterior oblique positions should be used. Sagittal,
transverse, coronal, and subcostal oblique views are suggested
using both a standard abdominal transducer and a higherfrequency
transducer. In many patients, the liver is tucked beneath
the lower right ribs, so a transducer with a small scanning face,
allowing an intercostal approach, is invaluable. Further, volumetric
imaging contributes greatly to the evaluation of the liver
as a single, appropriately selected acquisition may show virtually
the entire liver, allowing for a rapid portrayal of liver anatomy,
size, texture, and surface characteristics. 1 herefore diferentiation
of the difuse changes of cirrhosis and fatty liver from normal
are enhanced by review of the videos (Videos 4.1 and 4.2) of the
acquisitions as well as the multiplanar reconstructions (Fig. 4.1).
Ultrasound also best demonstrates the relationship of focal liver
masses to the vital vascular structures if surgical resection is
contemplated.
NORMAL ANATOMY
he liver lies in the right upper quadrant of the abdomen.
Functionally, it can be divided into three lobes: right, let, and
caudate. he right lobe of the liver is separated from the let by
the main lobar issure, which passes through the gallbladder
fossa to the inferior vena cava (IVC) (Fig. 4.2). he right lobe
of the liver can be further divided into anterior and posterior
segments by the right intersegmental issure. he let intersegmental
issure divides the let lobe into medial and lateral
segments. he caudate lobe is situated on the posterior aspect
of the liver, with the IVC as its posterior border and the issure
for the ligamentum venosum as its anterior border (Fig. 4.3).
he papillary process is the anteromedial extension of the caudate
GB
RL
IVC
FIG. 4.2 Normal Lobar Anatomy. Right lobe of the liver (RL) can
be separated from left lobe of the liver (LL) by the main lobar issure
that passes through the gallbladder fossa (GB) and inferior vena cava
(IVC).
LL
FIG. 4.1 Normal Liver. Liver shown in a nine-on-one format from a volumetric acquisition acquired in the axial plane, with the center point on
the long axis of the portal veins at the porta hepatis.