THE PANCREAS

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THE PANCREAS
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• Introduction/General Information
• A. Located in epigastric left
  hypochondriac regions
• B. Dimensions
• 1. 5 - 6 length x
• 2. 1-1/2 width x
• 3. 1/2 - 1 thick
• C. Lies retroperitoneally at T-12/L-1 to
  L-3

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The Pancreas in situ
Right lobe of liver Falciform ligament Gallbladde
r Pancreas Duodenum
L-3
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Pancreas, Introduction, continued D.
Head fills concavity of duodenum E. Body
crosses left kidney F. Tail reaches hilus of
the spleen G. Related anteriorly to
transverse colon
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Pancreas in situ

• Duodenum
• Head of Pancreas

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• Pancreas, Introduction, continued
• H. Aorta, IVC lie posterior
• I. Uncinate process
• a. Lies posterior to SMA and SMV
• b. Lies anterior to aorta
• J. Neck lies anterior to SMV, with pylorus
  just above

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Venous Drainage of the Pancreas

• IVC
• SMV

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• Introduction, continued
• L. Body related posteriorly to left crus, left
  adrenal, left renal vein, and splenic vein
• Celiac Axis (trunk, artery) lies superior to
  body

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II. Detailed Anatomy

• A. Landmark structures
• 1. Splenic Artery
• a. Branch of celiac trunk
• b. passes right to left
• c. Course is along upper margin of
  body and tail

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Detailed Anatomy, cont 2. Hepatic Artery
a. Branch of celiac trunk b. courses
left to right c. along upper margin of neck
and head 3. Superior Mesenteric Artery
at its origin from aorta, points at body
of pancreas
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Arterial Supply to Pancreas
Proper Hepatic Artery
Common Hepatic Artery
Superior Mesenteric Artery
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Landmark structures, continued
4. Splenic Vein a. runs parallel to
artery b. on posterior surface of
pancreas c. Terminates in portal vein
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Landmark structures, continued
5. Superior Inferior Mesenteric Veins a.
pass (inferior to superior) deep
to pancreas b. merge with splenic vein
c. Terminate in portal vein
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Landmark structures, continued
6. Common Bile Duct a. passes behind
first portion of duodenum b. then
through head of pancreas c. Terminates at
ampulla of vater
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Detailed Anatomy continued

• B. Head of Pancreas
• 1. Important clinically because
• a. Numerous ducts and vessels traverse it
• b. Carcinoma usually located here

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Head of Pancreas, Detailed Anatomy, continued
2. Tumor will compress surrounding
structures a. First indication may be
jaundice b. Tumor may compress
duodenum c. May involve local
vessels Metastases may spread through these
vessels
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Head of Pancreas, Detailed Anatomy, continued
3. Lymphatics from head of pancreas a.
Drain to celiac nodes b. metastases may
follow lymph c. Metastases may spread via
lesser omentum to liver d. Some terminate
in lumbar nodes
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Head of Pancreas, Detailed Anatomy, continued
4. Vessels supplying head of pancreas a.
Superior inferior pancreaticoduodenal
arteries b. Both divide into two parallel
vessels c. one anterior and one posterior
to head
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Head of Pancreas, Detailed Anatomy, continued

• Anterior branch of pancreaticoduodenal artery
• a. superior branch anterior superior
  pancreaticoduodenal artery
• b. inferior branch anterior inferior
  pancreaticoduodenal
• artery

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Head of Pancreas, Detailed Anatomy, continued

• 2. Posterior branch of pancreaticoduodenal
  artery
• a. superior branch posterior superior
  pancreaticoduodenal artery
• b. inferior branch posterior inferior
  pancreaticoduodenal artery
• extensive blood supply

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Anterior Pancreaticoduodenal Artery

• Branches are continuous with one another
• Superior branches originate from the GDA
• Inferior branches originate from the SMA

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• Detailed Anatomy, continued
• Body Tail of Pancreas
• 1. Supplied by splenic artery 2. Have
  three surfaces
• a. Anterior surface
• 1. Concave
• 2. Deep to stomach
• 3. Separated from stomach by
  lesser sac of peritoneum
• (aka omental bursa)

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Anterior surface of pancreas
Epiploic foramen
Anterior surface of pancreas
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Lesser sac, continued 4. Lesser sac bounded
by a. Liver, superiorly b. Below, extends to
greater omentum c. Anteriorly lesser
omentum, stomach, greater omentum
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• Lesser sac, continued
• d. Posteriorly greater omentum transverse
  colon, transverse mesocolon
• e. Laterally
• Foramen of Winslow on right
• Spleen on left

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Detailed Anatomy, continued f. Foramen of
Winslow (AKA Epiploic Foramen)
1. Lies between greater lesser sacs
of peritoneum 2. posterior to free edge of
lesser omentum 3. close to porta
hepatis
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Three Surfaces, continued 2. Posterior
surface separated from vertebrae by a.
Aorta b. Splenic vein c. Left kidney and
renal vessels d. Left adrenal gland e. Left
Crus of diaphragm f. SMA and SMV
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Three surfaces, continued 3. Inferior
surface of Pancreatic body a. Rests on
duodeno-jejunal flexure b. Left extremity
(tail) 1. Rests on splenic flexure 2.
Abuts hilus of spleen
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Detailed Anatomy, continued D. Pancreatic
Duct System 1. Pancreatic Duct (of Wirsung)
a. Course is left to right b. Receives
numerous small ducts c. _at_ neck of pancreas,
duct turns inferior, posterior to the
right d. AKA main pancreatic duct
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Duct of Wirsung (Main pancreatic duct)
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• Pancreatic Duct System, continued
• d. joins CBD at Ampulla of Vater 3 - 4
  below pylorus
• e. results from fusion of ducts during
  fetal development
• 1. One from ventral pancreas
  2. One from dorsal pancreas
• (see Netters Embryology, p. 142, for
  Pancreas development)

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Duct of Wirsung
Duct of Wirsung
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• Pancreatic Duct System, continued
• 2. Duct of Santorini
• a. accessory pancreatic duct
• b. Not universally identified
• joins duodenum _at_ minor papilla
• d. part of duct from dorsal pancreas

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Duct of Santorini
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Pancreatic Duct System, continued 3. In
10 of population a. ducts fail to fuse
b. result is drainage of tail, body,
most of head through minor papilla c.
Not pathological
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III. Scanning Anatomy A. Depends on
recognition of pancreatic margins B.
Sonography best used as screening
procedure 1. May be interference from bowel
gas (especially in tail region)
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Scanning Anatomy, continued 2. Extremely
accurate in detection of pseudocysts
3. U/S can show texture of organ 4. By
ID-ing vessels, can delineate head, portions
of body
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Scanning Anatomy, continued 5. U/S can
frequently detect dilation of
pancreatic duct 6. Splenic Vein landmark
vessel a. usually seen along posterior
margin of body, tail b. May be anterior
(30)
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Scanning Anatomy, continued C. Head
1. SMV outlines medial head to neck
region 2. Duodenum GB outline lateral
head 3. Superiorly, delineated by
gastroduodenal artery (GDA) 4. Inferiorly,
bounded by CBD
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• Scanning Anatomy, continued
• D. Further delineation by vascular
  landmarks
• SMA
• a. Lies immediately posterior to body,
  points to it!
• b. Recognized by echogenic fat collar
  surrounding vessel

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Vascular Landmarks of the Pancreas

• Pancreatic sonography depends largely on
  identifying surrounding landmark vessels

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Scanning Anatomy, continued 2. SMV
a. Delineates medial head b. Larger
diameter than SMA c. Lies to right of
SMA d. Uncinate process wraps it (and SMA),
lies posterior medial
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Vascular Landmarks of the Pancreas

• Venous landmarks of the pancreas include the SMV
  and renal veins

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Scanning Anatomy, continued
3. Left Renal Vein a. as it enters IVC
b. head uncinate process should
lie within 1 2 cm c. Landmark vessel
posterior to body of pancreas
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• Scanning Anatomy, continued
• E. Tail of Pancreas
• 1. May be visualized through fluid-filled
  stomach
• 2. Tail seen as 2-3 cm rounded
  mass anterior to hilus of left kidney

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IV. Pancreatic Disorders A. Pancreatitis
diagnosis depends on clinical evidence
1. Usually secondary to biliary tract
disease 2. Surgery of biliary tract or
stomach, alcoholism are other causes
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Pancreatitis, Pancreatic Disorders, continued
3. Infrequent causes a. Infectious
diseases b. Trauma d. Drugs e.
Hyperparathyroidism 4. Inflammation may be
diffuse or spotty
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Pancreatitis, Pancreatic Disorders, continued
5. Important factor is release of protein
kinins a. Increase permeability of
vessels cells b. Releases tissue
fluid c. Edema may compress vessels d.
Tissue damage occurs
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Pancreatitis, Pancreatic Disorders, continued
6. WBCs may increase to 20,000/ml 7.
Increase in pancreatic enzymes a. serum
bilirubinase (by 25) b. serum amylase
c. serum lipase
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Pancreatic Disorders, continued
B. Pseudocysts 1. False cysts that may
arise a. due to tissue necrosis b. From
enzymatic destruction 2. May persist after
inflammation subsides 3. Usually near or in
pancreas
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Pancreatic Disorders, continued 4.
Rarely, may be elsewhere a. in abdomen or
pelvis b. Rarely, mediastinum 5. Pseudocyst
appearance a. unilocular or multilocular
b. echoes from pus cellular debris
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Pancreatic Diseases, continued C. Acute
Pancreatitis 1. Diffuse enlargement 2. Less
echogenic due to edema 3. Echogenicity
usually gt liver parenchyma
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Pancreatic Diseases, continued D. Chronic
Pancreatitis 1. organ usually appears as small,
atrophic 2. Contains scattered echoes
from calcifications 3. Primary cause is
alcoholism
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Pancreatic Diseases, continued E. Dilation
of Pancreatic Duct 1. Seen in acute or chronic
pancreatitis 2. Frequently associated
with neoplasm of pancreas 3.
Biliary tract problems
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Pancreatic Diseases, continued F.
Abscess or Hemorrhagic Pancreatitis 1.
Similar in sonographic appearance 2.
Hemorrhagic a. Mass with inhomogeneous
texture b. Acute hemorrhage sonolucent to
echogenic c. CT scan used for
differentiation
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Pancreatic Disorders, continued G.
Pancreatic Tumors 1. Malignant tumors usually
arise as adenocarcinomas 2. In head of
Pancreas Sx a. Painless jaundice b.
Anorexia
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Pancreatic Tumors, In head, continued c.
Nausea d. Weight loss e. Increased plasma
amylase f. Increased alkaline phosphatase g.
May involve compression of pancreatic
duct, CBD
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Pancreatic Tumors in the Head

• Tumors in the head may compress biliary ducts or
  pancreatic ducts

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Pancreatic tumors, continued 3. In Body of
Pancreas Sx a. Gnawing pain radiating to
back b. Pain increases after eating or
lying down c. Weight loss, anorexia d.
Large tumor may compress IVC, portal vein
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Pancreatic tumors, continued 4. In Tail of
Pancreas Sx a. Often silent until local
metastasis occurs b. May metastasize to
1. para-aortic lymph nodes 2.
spleen
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Pancreatic tumors, continued 5. Identified
by organ enlargement, subtle echo
changes, irregular outline 6. Metastases to
stomach, liver lungs are
common 7. Often causes dilation of ducts
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• Pancreatic Disorders, continued
• H. Fibrocystic Disease
• 1. Result of cystic fibrosis
• 2. Diagnosed by methods other than
  ultrasound

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Pancreatic Disorders, continued I.
Pancreaticolithiasis 1. Characteristic stone
echoes in pancreatic duct 2. May see atrophied
pancreatic parenchyma 3. Associated with
chronic alcoholic pancreatitis 4. Contours of
body, tail show irregularities
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Pancreatolithiasis, continued 5.
Incidence slightly higher in head 6.
Associated with occult pancreatic
carcinoma a. Mass lt 2mm diameter b. Seen
with dilation of pancreatic duct or CBD