Imaging Anatomy of the Pancreas

Ben BarnardDepartment of Diagnostic Radiology; KHC

Outline Embryology Variants Gross anatomy Anatomical relations Arterial supply Venous drainage Lymphatic drainage Radiological anatomy

Embryology The pancreas is formed by dorsal and ventral buds originating

from the endodermal lining of the duodenum The smaller ventral bud arises in conjunction with the bile duct

and consists of two portions Left bud which atrophies during development Right bud which swings posteriorly and unites with the inferior division

of the dorsal bud

Langman’s Medical Embryology

Variants Agenesis of the dorsal pancreatic moeity

Pancreas with a head but no body or tail – very rare Left-sided pancreas

Effect of age with laxity of suspensory fascia Accessory nodules (pancreatic rests)

Can occur in the wall of the stomach, duodenum, jejunum , appendix, Meckel’s diverticulum (1-15% )

Pancreas divisum Failure of fusion of dorsal and ventral moeities Anterosuperior head and body drain via accessory ampulla Posterioinferior head drains to ampulla

Annular pancreas

Annular pancreas Occurs when the left portion of the ventral bud fails to atrophy

and migrates around the duodenum in the opposite direction to the normal right portion

Duodenum is thus surrounded bypancreatic tissue, and an annular pancreas is formed

This tissue constricts the duodenum and may cause complete obstruction

Gross Anatomy Retroperitoneal

organ 15cm long Transverse

mesocolon originates from anterior surface.

Head C-curve of duodenum (L2)

Uncinate process Inferior-medial extension

of head under SMA (L2) Neck

Overlies L1 vertebral body immediately to the left of the head

Body Extends left and slightly

superior (L1) Tail

Tapering portion extending to hilum of spleen (T12)

Various normal shapes

Anatomical Relations

Anterior relations Peritonium 1st part

duodenum Lesser sac and

stomach Transverse

colon/mesocolon

Anatomical Relations Posterior relations

CBD IVC PV Aorta SMA SMV Right renal vein Left kidney Crurae of

diaphragm.

Retroperitoneal Compartments

The pancreas (P) lies in the anterior pararenal space (APRS) together with the ascending and descending colon (C) and duodenum ST = stomach S = spleen RK = right kidney LK = left kidney A = aorta V = inferior vena cava LS = lesser sac PRS = perirenal space PPRS = posterior pararenal

space

Grants Anatomy

Pancreatic duct Pancreatic duct measures

3mm in the head 2mm in the neck 1mm in the tail

Unites with the common bile duct to form the ampulla of Vater and opens into the 2nd part of duodenum

Pancreatic duct variants

Santorini Wirsung

Arterial supply Pancreas neck, body and tail

Dorsal pancreatic artery (from splenic artery or coeliac trunk) Pancreatica magna artery ( emerges halfway along the splenic artery) Transverse pancreatic artery (travels along the length of the pancreatic duct

and anastomoses with the above arteries) Pancreas head

Superior pancreaticoduodenal artery (anterior and posterior branches from the gastroduodenal artery) Inferior pancreaticoduodenal artery (anterior and posterior branches from the superior mesenteric artery)

Venous drainage SMV Splenic vein Portal vein

Lymphatic drainage Along arterial blood supply to pre-aortic coeliac lymph

nodes

Radiological anatomy

US 3 - 7.5 MHz probe Sagittal, transverse and oblique planes Occasionally, may have non-visualization due to bowel

gas which can be overcome by:1. Fill stomach with fluid2. Position patient erect (liver descends)3. Prone position for tail

CT Similar density as

liver Density is reduced

with increasing age due to normal accumulation of fat

Homogenous enhancement post contrast

MRI

ERCP

MRCP

References• Imaging Anatomy of the Pancreas Referaat, Dr Frans Naude• Normal Findings in CT and MRI,Moeller• Pocket Atlas of Sectional Anatomy Computer Tomography and

Magnetic Resonance Imaging, Torsten B. Moeller, MD• Last’s anatomy 11th ed , Sinnatamby• Applied radiological anatomy , Butler• Atlas of human anatomy, F Netter• Pocket Atlas of Radiographic Anatomy,second edition,Moeller• Atlas of normal rontgen variants that may simulate disease, R

Keats• Color Atlas of Ultrasound Anatomy ,Berthold Block• Grant atlas of anatomy