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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5782_Библиотеки_им_академика_М_И_Перельмана.pdf
CHAPTER 8 Pancreas Scanning Protocol 149
Posterior
Gastroduodenal
Physiology
• The pancreas has both endocrine and exocrine functions:
• Endocrine function: produces the hormone insulin to prevent
diabetes mellitus.
• Exocrine function: produces pancreatic enzymes that, via the
pancreatic ducts, aid digestion.
Sonographic Appearance
• Because the pancreas lies at a horizontal oblique in the body, the
longitudinal and long axis sections are visualized in an obliqued
transverse scanning plane. The following obliqued, transverse
scanning plane image shows the long axis of a normal adult
pancreas.
Anterior
Left renal vein
Splenic vein
Aorta
Spine
Superior
mesenteric
vein
Common
bile duct
Head
Inferior
vena
cava
Right renal
artery
Liver
Neck
artery
Uncinate
process
Notice how the pancreas appears midgray, with even texture
that is moderately hyperechoic relative to the normal liver
(in many cases the pancreas will appear isosonic to the liver).
Observe the smooth contour of the pancreas and how it is
distinguishable from adjacent structures (the pancreas is nonencapsulated, so it can be infiltrated by retroperitoneal fat
making the contour uneven and difficult to evaluate in some
cases). The anechoic, longitudinal section of the splenic vein
running along the posterior margin of the pancreas body serves
as an easily recognizable vascular landmark when identifying
Body
Bowel
Bowel
shadow
LeftRight
Tail
Superior
mesenteric
artery
150 PART III Abdominal Scanning Protocols
Gastro-
Posterior
the pancreas. Notice how the splenic vein (coming from the
splenic hilum) courses along the posterior aspect of the pancreas to join with the superior mesenteric vein directly
behind, or posterior to, the pancreas neck (they join to form
the portal vein).
The head of the pancreas is easily identified as it sits directly in front
of, or anterior to, the inferior vena cava and is distinguished by
the small anechoic axial sections of the gastroduodenal artery
on its anterolateral border and the common bile duct on its posterolateral border. The pancreas tail is usually the most difficult
part of the pancreas to visualize because it lies behind, or posterior to the stomach; however, it is well demonstrated in this
image. Observe how the tail is left lateral to the spine and aorta
and more posterior than the pancreas head.
• The axial sections of the pancreas are visualized in sagittal scan-
ning planes (pictured on the facing page). The top scan A, is a
sagittal scanning plane image showing an axial section of the
pancreas head. It is easily identified as it sits directly anterior to
the anechoic, longitudinal inferior vena cava and is distinguished
by the small, anechoic, longitudinal sections of the gastroduodenal artery on its anterior border and the common bile duct on its
posterior border.
Hepatic
artery
Superior
Portal
vein
Right renal artery
Gallbladder neck fold shadow
Anterior
Gallbladder
Liver
duodenal
artery
Middle IVC
Common
bile duct
Pancreas
head
Inferior
A
CHAPTER 8 Pancreas Scanning Protocol 151
Posterior
Splenic
Body
The anatomy in the bottom image B, is the same as the anatomy
in the top image but the view is different. Now we see a transverse scanning plane image showing a long section of the pancreas; the head is clearly distinguished as it sits just anterior to
the anechoic, axial inferior vena cava and the anechoic, axial
sections of the gastroduodenal artery (anteriorly) and the com-
mon bile duct (posteriorly) are easily identified.
Gastroduodenal
artery
Neck
Liver
Duodenum
Head
Common
bile duct
Inferior
vena
cava
Right
renal
B
artery
Refraction
shadow
Right crus of
Through
transmission
Superior
mesenteric
Anterior
Spine
diaphragm
vein
Aorta
Uncinate
process
Superior
mesenteric
artery
vein
LeftRight
Left
renal
vein
Left renal
artery
152 PART III Abdominal Scanning Protocols
Anterior
rior
Posterior
Posterior
a
Superior
• The next images demonstrate axial and longitudinal views of the
pancreas neck, uncinate process, and the superior mesenteric vein that
separates them. The top scan A, is a sagittal scanning plane image,
showing a longitudinal view of the superior mesenteric vein separating axial sections of the pancreas neck (seen anteriorly) and
uncinate process (seen posteriorly). The bottom image B, is the
same as the anatomy in the top image but the view is different.
Now we see a transverse scanning plane image showing longitudinal views of the pancreas neck (anteriorly) and uncinate process
(posteriorly), clearly separated by the anechoic, round, axial section of the superior mesenteric vein.
Hepatic
artery
Superior
Liver
Neck
Superior
mesenteric vein
Uncinate process
Inferior
vena cava
Infe
A
Common
bile duct
mesenteric vein
Liver
Bowel
Neck
Anterior
Body
Superior
mesenteric
artery
Stomach/
bowel
LeftRight
Aort
B
Inferior
vena cava
Gastroduodenal
artery
Head
Uncinate
process
Crus
Left renal
vein
Spine
CHAPTER 8 Pancreas Scanning Protocol 153
Body
Posterior
Posterior
Neck
Splenic vein
• The splenic vein and superior mesenteric artery serve as vascular land-
marks when identifying the body of the pancreas. The top scan A, is
a sagittal scanning plane image demonstrating an axial view of the
pancreas body. Observe how the body is seen directly anterior to the
anechoic, axial section of the splenic vein, which lies just anterior to
the anechoic superior mesenteric artery seen in longitudinal section
as it branches from the aorta. The splenic artery marks the superior
edge of the pancreas body. Two anechoic, round, axial sections of the
splenic artery are easily identified in this image. The anatomy in the
bottom transverse scanning plane image B, is the same as the anatomy
in the top image but the view is different. Now we see a longitudinal
view of the pancreas body. Notice how the body sits just anterior to
an anechoic, long section of the splenic vein, which is just anterior to
the anechoic, round, axial section of the superior mesenteric artery.
Anterior
Superior
Splenic vein
Inferior
Liver
Proximal
aorta
Middle aorta
Anterior
Right crus of diaphragm
Right renal artery
artery
Head
Portal
splenic
Right
Splenic artery
Liver
Inferior
vena cava
A
Gastroduodenal
confluence
B
Common
bile duct
Stomach
Superior
mesenteric
artery
Body
Superior
mesenteric
artery
Left
renal vein
Aorta
Pancreas
Uncinate process
Spine
Tail
Left
tail
154 PART III Abdominal Scanning Protocols
Anterior
Posterior
in
Posterior
Neck
• The splenic vein also serves as a vascular landmark when identify-
ing the tail of the pancreas. The left kidney is helpful when locating the tail as well (pictured below). The top scan A, is a sagittal
scanning plane image, showing an axial section of the pancreas
tail seen anterior to the anechoic, long splenic vein section and left
kidney. The bottom scan B, is a transverse scanning plane image
demonstrating the same anatomy as the top image but the view
is different. Now we see a longitudinal view of the pancreas tail
clearly anterior to the anechoic, axial splenic vein section, left lateral to the spine and posterior to the stomach. Note the left kidney
directly posterior to the splenic vein.
Superior
Left lobe
of liver
Bowel
Tail
Inferior
Splenic ve
Left
kidney
A
Uncinate
process
Left renal
vein
Head
Inferior
vena cava
B
Anterior
Liver
Spine
Aorta
Body
Stomach
Superior
mesenteric
artery
LeftRight
Tail
Splenic
vein
Left
kidney
CHAPTER 8 Pancreas Scanning Protocol 155
Posterior
Gastroduodenal
• Wirsung’s duct (or the pancreatic duct) is commonly seen and most
frequently in the body portion of the pancreas. It appears anterior to the anechoic, long splenic vein sections either as a long,
thin, bright line or as an anechoic, longitudinal section bordered
by thin, bright walls as seen in the following image:
artery
Head
Common
bile duct
Right
Duodenum
Inferior
vena cava
Right
renal
artery
Spine
Anterior
Neck
Liver
Normal Variants
• The size, shape, and lie of the pancreas are normally variable.
• The duct of Santorini is a normal variant accessory duct.
Preparation
Body
Stomach
Tail
Splenic
vein
Confluence
of superior
mesenteric vein
and splenic vein
Wirsung’s
duct
Left
Aorta
Left
kidney
Patient Prep
• The patient should fast for 8 to 12 hours before the study. This
reduces the amount of stomach and bowel gas anterior to the pancreas and ensures normal gallbladder and biliary tract dilatation,
which is significant because the pancreas and biliary tract are interdependent systems.
• If the patient has eaten, still attempt the examination because in
some cases, stomach contents can displace gas and serve as a “window” for the sound beam. Also, for this reason, the patient can
be given 2 to 4 cups of water or noncarbonated drink to provide
a sonic window and displace any gas in the stomach that may be
obscuring the view of the pancreas. In most cases, this fluid technique works best if the patient is sitting erect.
NOTE: When using a fluid technique, peristalsis can cause the fluid to pass
very quickly through the stomach and duodenum not allowing enough
time to fully evaluate the area of interest. Therefore, peristaltic-reducing
drugs can be administered to the patient to slow down peristaltic action.
156 PART III Abdominal Scanning Protocols
Pat
Transducer
• Curved array 5.1 MHz or 5.2 MHz.
• 10.4, 8.5 MHz for thin patients.
Breathing Technique
• Deep, held inspiration.
NOTE: Different breathing techniques should be used whenever the
suggested breathing technique does not produce the desired results.
Patient Position
• Supine.
• Sitting semi-erect to erect, left posterior oblique, left lateral decubitus,
or prone as needed.
NOTE: Different patient positions should be used whenever the suggested positions do not produce the desired results.
Pancreas Survey Steps
Pancreas • Longitudinal Survey
Transverse Plane • Transabdominal Anterior Approach
1. Begin scanning with the transducer perpendicular, at the midline of
the body, just inferior to the xiphoid process of the sternum. Have
the patient take in a deep breath and hold it. Slightly rock the transducer superior to inferior while slowly sliding the transducer inferiorly. Look for the body of the pancreas to come into view just inferior
to the level of the celiac axis branch of the aorta. You should be
able to identify an anechoic, longitudinal section of the splenic vein
running along the posterior margin of the pancreas body. Round,
anechoic, axial sections of the superior mesenteric artery and the
aorta should be seen posterior to the long section of the splenic vein.
LT
Patient’s left (LT)
ient’s right (RT)
RT
CHAPTER 8 Pancreas Scanning Protocol 157
2. When the pancreas body is identified, it may be necessary to
very slightly twist/rotate the transducer—first one way, then the
other—to resolve the long axis of the body. Then, to evaluate the
rest of the pancreas body, begin by moving the transducer very
slowly superiorly, scanning through and beyond the pancreas margin. Now very slowly slide the transducer inferiorly back onto the
body until you scan through and beyond the pancreas. Look for
the pancreatic duct(s) running through the center of the body of
the pancreas.
LT
RT
LT
RT
3. To evaluate the tail, relocate the long axis of the pancreas body and
slightly move the transducer left lateral until you see the pancreas
tail in the area between the stomach (anteriorly) and left kidney
(posteriorly). As with the pancreas body, long sections or portions
of the anechoic splenic vein can be seen along the tail’s posterior
edge. When the tail is identified, it may be necessary to very slightly
twist the transducer—first one way, then the other—to resolve its
long axis. Then, to evaluate the rest of the pancreas tail, begin by
moving the transducer very slowly superiorly, scanning through
and beyond the pancreas margin. Now very slowly slide the transducer inferiorly until you scan through and beyond the tail. Look
for the pancreatic duct(s) in the central portion of the tail.
RT
LT
RT
LT
158 PART III Abdominal Scanning Protocols
NOTE: If gas from the stomach is obscuring the view of the pancreas tail
and the fluid technique cannot be utilized because the patient is restricted
from fluids, then you may have to evaluate the tail from an angle or from
a posterior approach. The angled view is obtained by relocating the pancreas body then angling the transducer toward the patient’s left at varying
degrees until the pancreas tail is identified. Once located, finish evaluating
the tail from that angle. (If any images are taken from an angle it must be
noted as part of the documentation.) When using a posterior approach,
the patient may sit erect or lie prone. It is usually helpful to begin by locating the superior pole of the left kidney (just lateral to the spine) then look
for the tail in the area directly anterior to the superior pole.
4. To evaluate the neck of the pancreas, relocate the long axis of the pancreas body and very slightly move the transducer right lateral. Look for
the pancreas neck to appear either directly anterior to the anechoic,
round axial section of the superior mesenteric vein or the anechoic
portal splenic confluence at its inferior portion. Very slightly twist-
ing/rotating the transducer can help resolve the longitudinal margins of the neck. To evaluate the rest of the pancreas neck, begin by
moving the transducer very slowly superiorly, scanning through and
beyond the pancreas margin. Now slowly slide the transducer inferiorly until you scan through and beyond the neck. You may see a
portion of the pancreatic duct in the central portion of the neck.
RT
LT
RT
LT
NOTE: If gas is obscuring the view of the pancreas neck and the fluid
technique cannot be utilized because the patient is restricted from
fluids, then you may have to evaluate the neck from an angle. The
angled view is obtained by relocating the pancreas body then angling
the transducer toward the patient’s right at varying degrees until the
pancreas neck is identified. Once located, finish evaluating the neck
from that angle. (If any images are taken from an angle it must be
noted as part of the image labeling.)