EMBRYOLOGY OF EMBRYOLOGY OF PANCREAS AND PANCREAS AND

IMAGING OF IMAGING OF PANCREATITISPANCREATITIS

Dr. Srikanth Dr. Srikanth reddy Vreddy V

DEVELOPMENT OF DEVELOPMENT OF PANCREASPANCREAS

• The pancreas develops in two parts, The pancreas develops in two parts, both of which arise from the both of which arise from the endoderm of the primitive duodenum.endoderm of the primitive duodenum.

• The dorsal bud is the first to appear, The dorsal bud is the first to appear, as a diverticulum from the dorsal wall as a diverticulum from the dorsal wall of the duodenum. This eventually of the duodenum. This eventually forms the whole of the neck, body forms the whole of the neck, body and tail of the gland, together with and tail of the gland, together with part of the head.part of the head.

• The ventral bud develops more The ventral bud develops more caudally as a diverticulum from the caudally as a diverticulum from the developing bile duct at the point developing bile duct at the point where the latter opens into the where the latter opens into the duodenum.duodenum.

• Soon after the appearance of the two parts, Soon after the appearance of the two parts, the duodenum undergoes partial rotation the duodenum undergoes partial rotation and they approximate each other and fuse. and they approximate each other and fuse. Until this stage the dorsal duct, the duct of Until this stage the dorsal duct, the duct of Santorini, opens into the duodenum Santorini, opens into the duodenum proximal to the major papilla (ampulla of proximal to the major papilla (ampulla of Vater) at the minor papilla, whereas the Vater) at the minor papilla, whereas the ventral duct, the duct of Wirsung, which is ventral duct, the duct of Wirsung, which is joined with the lower common bile duct, joined with the lower common bile duct, opens into the major papilla.opens into the major papilla.

• In the majority of cases, fusion of the In the majority of cases, fusion of the two ducts occurs at the junction of two ducts occurs at the junction of the head and body of the gland Thus the head and body of the gland Thus the main pancreatic duct opens into the main pancreatic duct opens into the major papillathe major papilla

CONGENITAL CONGENITAL ANAMOLIESANAMOLIES

• Pancreatic divisum: Pancreas divisum is the most common Pancreatic divisum: Pancreas divisum is the most common congenital pancreatic ductal anatomic variant congenital pancreatic ductal anatomic variant

• The abnormality results from failure of the dorsal and ventral The abnormality results from failure of the dorsal and ventral pancreatic anlage to fuse during the sixth to eighth weeks of pancreatic anlage to fuse during the sixth to eighth weeks of gestationgestation

• MRCP provides a noninvasive means of diagnosing pancreas MRCP provides a noninvasive means of diagnosing pancreas divisum without the use of contrast material and avoids the divisum without the use of contrast material and avoids the risk of ERCP-induced pancreatitis.risk of ERCP-induced pancreatitis.

•

MRCP pancreatic divisumMRCP pancreatic divisum

CT pancratic divisumCT pancratic divisum

• ANNULAR PANCREAS: 2ANNULAR PANCREAS: 2ndnd most common most common anamoly in which a band of pancreatic tissue anamoly in which a band of pancreatic tissue surrounds the descending duodenum, either surrounds the descending duodenum, either completely or incompletely, and is in continuity completely or incompletely, and is in continuity with the head of the pancreaswith the head of the pancreas

• CT or MR images may show normal pancreatic CT or MR images may show normal pancreatic tissue, with or without a small pancreatic duct, tissue, with or without a small pancreatic duct, encircling the duodenumencircling the duodenum

•

MRCP annular pancreasMRCP annular pancreas

CT annular pancreasCT annular pancreas

• Agenesis/hypoplasia: Agenesis/hypoplasia: complete agenesis is complete agenesis is very rare but very rare but hypoplasia may be hypoplasia may be seenseen

• ECTOPIC PANCREATIC ECTOPIC PANCREATIC TISSUE:Ectopic rests of pancreatic TISSUE:Ectopic rests of pancreatic tissue are usually located in either the tissue are usually located in either the submucosa of the gastric antrum or submucosa of the gastric antrum or the proximal portion of the duodenumthe proximal portion of the duodenumVariations of Pancreatic Ducts:A bifid Variations of Pancreatic Ducts:A bifid pancreatic duct is an anomaly in pancreatic duct is an anomaly in which the main pancreatic duct is which the main pancreatic duct is bifurcated along its lengthbifurcated along its length

Imaging acute Imaging acute pancreatitispancreatitis

INDICATIONS OF INDICATIONS OF IMAGINGIMAGING

The clinical signs of acute pancreatitis are The clinical signs of acute pancreatitis are nonspecific, with serum amylase and lipase nonspecific, with serum amylase and lipase levels correlating poorly with disease levels correlating poorly with disease severity . Elevated plasma serum amylase and severity . Elevated plasma serum amylase and lipase levels are not specific to acute lipase levels are not specific to acute pancreatitis and may be elevated by bowel pancreatitis and may be elevated by bowel obstruction, infarction, cholecystitis, and obstruction, infarction, cholecystitis, and perforated ulcer. Imaging is recommended to perforated ulcer. Imaging is recommended to confirm the clinical diagnosis, diagnose its confirm the clinical diagnosis, diagnose its cause, exclude alternative causes of cause, exclude alternative causes of abdominal pain, and grade the extent and abdominal pain, and grade the extent and severity of acute pancreatitis severity of acute pancreatitis

Acute Pancreatitis Acute Pancreatitis PathophysiologyPathophysiology

• Blockage of the pancreatic duct leads to increased pressure Blockage of the pancreatic duct leads to increased pressure in pancreatic duct and rupture. in pancreatic duct and rupture.

• Pancreatic fluid (proteolytic and lipolytic enzymes) ruptures Pancreatic fluid (proteolytic and lipolytic enzymes) ruptures into pancreas parenchyma and anterior pararenal space into pancreas parenchyma and anterior pararenal space

Gore and Levine, Textbook of Gastrointestinal Radiology

IMAGING MODALITIESIMAGING MODALITIES Imaging of pancreasImaging of pancreas• Radiograph– detect calcification Radiograph– detect calcification

(practically of no help)(practically of no help)• USG – differentiation of cystic and USG – differentiation of cystic and

solid lesions (screening tool & for solid lesions (screening tool & for follow-up)follow-up)

• CT scan – modality of choiceCT scan – modality of choice• MRI and MRCP – complimentary to CTMRI and MRCP – complimentary to CT

Imaging Goals in PancreatitisImaging Goals in Pancreatitis1.1. Exclude other abdominal disorders that can Exclude other abdominal disorders that can

mimic acute pancreatitismimic acute pancreatitis– DDx: acute cholecystitis, bowel obstruction or DDx: acute cholecystitis, bowel obstruction or

infarction, perforated viscus, renal colic, duodenal infarction, perforated viscus, renal colic, duodenal diverticulitis, aortic dissection, appendicitis, and diverticulitis, aortic dissection, appendicitis, and ruptured abdominal aortic aneurysmruptured abdominal aortic aneurysm

2.2. Confirm clinical diagnosis of acute Confirm clinical diagnosis of acute pancreatitispancreatitis

3.3. Staging the disease, by evaluation of the Staging the disease, by evaluation of the extent and nature of pancreatic injury and extent and nature of pancreatic injury and peripancreatic inflammationperipancreatic inflammation

TYPESTYPES• The revised Atlanta classification The revised Atlanta classification

(2012) of acute pancreatitis divides (2012) of acute pancreatitis divides the condition into the condition into

• interstitial oedematous pancreatitis interstitial oedematous pancreatitis and necrotising pancreatitis, (formerly and necrotising pancreatitis, (formerly termed mild and severe acute termed mild and severe acute pancreatitis).This morphological pancreatitis).This morphological classification system is based on classification system is based on findings on contrast-enhanced CTfindings on contrast-enhanced CT

Interstitial Oedematous Interstitial Oedematous PancreatitisPancreatitis

• imaging findings in interstitial imaging findings in interstitial oedematous pancreatitis include oedematous pancreatitis include focal or diffuse enlargement of the focal or diffuse enlargement of the gland, with normal homogeneous gland, with normal homogeneous enhancement or slightly enhancement or slightly heterogeneous enhancement of the heterogeneous enhancement of the pancreatic parenchyma, which is pancreatic parenchyma, which is attributable to oedema.attributable to oedema.

Necrotising PancreatitisNecrotising Pancreatitis• This is the hallmark of severe acute This is the hallmark of severe acute

pancreatitis. The revised Atlanta pancreatitis. The revised Atlanta classification distinguishes three forms classification distinguishes three forms of acute necrotising pancreatitis: of acute necrotising pancreatitis: pancreatic parenchymal necrosis pancreatic parenchymal necrosis alone, peripancreatic necrosis alone, alone, peripancreatic necrosis alone, and pancreatic necrosis with and pancreatic necrosis with peripancreatic necrosis. All three types peripancreatic necrosis. All three types can be sterile or infectedcan be sterile or infected

Abdominal Plain FilmAbdominal Plain FilmFindings of Acute Findings of Acute

Pancreatitis on Pancreatitis on Abdominal Plain FilmAbdominal Plain Film– Duodenal ileus Duodenal ileus – Colon cutoff (paucity of Colon cutoff (paucity of

gas distal to splenic gas distal to splenic flexure due to spasm of flexure due to spasm of colon affected by spread colon affected by spread of pancreatic of pancreatic inflammation)inflammation)

– Pancreatic abscess (gas Pancreatic abscess (gas bubbles)bubbles)

– Gasless abdomen due to Gasless abdomen due to excessive vomitting.excessive vomitting.

– Loss of psoas shadow.Loss of psoas shadow.

Plain Chest FilmPlain Chest Film• Findings of Acute Pancreatitis Findings of Acute Pancreatitis

on Plain Chest Film:on Plain Chest Film: Left sided pleural effusions (seen Left sided pleural effusions (seen

on 10% of chest films)on 10% of chest films)– basal atelectasisbasal atelectasis– pulmonary infiltratespulmonary infiltrates– Splinting of left diaphragm and Splinting of left diaphragm and

basal parenchymabasal parenchyma

Colon cut-off signColon cut-off sign

UltrasoundUltrasound• IndicationsIndications

– Good screening test in mild disease, suspected biliary Good screening test in mild disease, suspected biliary pancreatitispancreatitis

• UsesUses– Detection of gallstonesDetection of gallstones– Bile duct obstructionBile duct obstruction– Follow up of pseudocystsFollow up of pseudocysts– diagnosis of vascular complications, i.e. thrombosisdiagnosis of vascular complications, i.e. thrombosis

• Major LimitationsMajor Limitations– Bowel gas Bowel gas – US cannot specifically reveal areas of necrosis US cannot specifically reveal areas of necrosis

Ultrasound findings Ultrasound findings • Enlargement of pancreas- Universal but Enlargement of pancreas- Universal but

not specific , upper limit of normal not specific , upper limit of normal pancreatic thickness=22 mmpancreatic thickness=22 mm

• Pancreatic echogenicty(subjective) Pancreatic echogenicty(subjective) decreases due to oedema but sometime decreases due to oedema but sometime rarely can be increased due to rarely can be increased due to haemorrhage, necrosis, fat saponification.haemorrhage, necrosis, fat saponification.

• ““pseudopancreatitis”- pacreatic pseudopancreatitis”- pacreatic echogencity decreased due to fatty echogencity decreased due to fatty filtration.filtration.

• Pancreatic inflammation- hypoechoic/ Pancreatic inflammation- hypoechoic/ anechoicanechoic

• Difficult to distinguish inflammaton from Difficult to distinguish inflammaton from fluidfluid

• Ventral and adjacent to pancreas in pre-Ventral and adjacent to pancreas in pre-pancreatic retroperitoneum, rt and left ant pancreatic retroperitoneum, rt and left ant pararenal spaces, perinal spaces, transverse pararenal spaces, perinal spaces, transverse mesocolon.mesocolon.

• But fluid is more localised,thicker, But fluid is more localised,thicker, causemass effectcausemass effect

CT FINDINGSCT FINDINGS

• CT is the imaging modality of choice CT is the imaging modality of choice for the diagnosis and staging of for the diagnosis and staging of acute pancreatitis and its acute pancreatitis and its complications.complications.

COMPLICATIONSCOMPLICATIONS• Acute fluid collectionsAcute fluid collections• PeudocystsPeudocysts• Pancreatic abscessPancreatic abscess• NecrosisNecrosis• HaemorrhageHaemorrhage• Venous thromboembolismVenous thromboembolism

Targets of Inflammatory spreadTargets of Inflammatory spread in Acute Pancreatitis in Acute Pancreatitis

• 1= spread into the lesser 1= spread into the lesser sac sac

• 2 = spread into the 2 = spread into the transverse mesocolon transverse mesocolon

• 3 = spread into the root 3 = spread into the root of the bowel mesentery of the bowel mesentery

• 4 = extension into the 4 = extension into the duodenum duodenum

• 5= inferior spread into 5= inferior spread into the remainder anterior the remainder anterior pararenal spacepararenal space

• 6=RP fluid colecting 6=RP fluid colecting down to scrotum,or even down to scrotum,or even thighthigh

Gore and Levine, Textbook of Gastrointestinal Radiology

Differential diagnosisDifferential diagnosis• Infiltrating pancreatic carcinomaInfiltrating pancreatic carcinoma• Lymphoma and metsLymphoma and mets• Chronic pancreatitisChronic pancreatitis• Perforated duodenl ulcerPerforated duodenl ulcer

Computed TomographyComputed Tomography““CT is the premier imaging test in the diagnosis CT is the premier imaging test in the diagnosis

and management of patients with acute and management of patients with acute pancreatitis. It visualizes the gland, the pancreatitis. It visualizes the gland, the retroperitoneum, the abdominal ligaments, the retroperitoneum, the abdominal ligaments, the mesenteries, and the omenta in their entirety.”mesenteries, and the omenta in their entirety.”

Bilateral fluid accumulation in dependent lung regions

Chest CT: Pleural EffusionChest CT: Pleural Effusion

ROI: 5 HU (simple fluid)

Acute Interstitial pancreatitisAcute Interstitial pancreatitis

Necrotizing pancreatitisNecrotizing pancreatitis

Necrotizing pancreatitisNecrotizing pancreatitis

Pseudocyst in Lesser Sac or Gastric WallPseudocyst in Lesser Sac or Gastric Wall

ROI: •12 HU (simple fluid)

•69mm x 36mm

Extensive pancreatic Extensive pancreatic necrosisnecrosis

Normal BowelWall Edematous,

Inflamed Bowel Wall

Inflamed Fat

Normal Fat

Inflammation Spreads to the Transverse ColonInflammation Spreads to the Transverse Colon

Pancreatic AscitesPancreatic Ascites

Dependent fluid collection between liver and diaphragmROI: 14 HU

Traditional CT severity Traditional CT severity indexindex

Modified CT severity index-Modified CT severity index-easier wayeasier way

• Total scoreTotal score• Total points are given out of 10 to Total points are given out of 10 to

determine the grade of pancreatitis and determine the grade of pancreatitis and aid treatment:aid treatment:

• 0-2: mild0-2: mild• 4-6: moderate4-6: moderate• 8-10: severe8-10: severe•

Fluid collectns assc with Fluid collectns assc with acute pancreatitisacute pancreatitis

APFCAPFCAcute Peripancreatic Fluid Collections Acute Peripancreatic Fluid Collections contain fluid only and are not or only contain fluid only and are not or only partially encapsulated. They are seen within partially encapsulated. They are seen within 4 weeks in interstitial pancreatitis4 weeks in interstitial pancreatitis

• ANCANCAcute Necrotic Collections contain a mixture Acute Necrotic Collections contain a mixture of fluid and necrotic material. They are not of fluid and necrotic material. They are not or only partially encapsulated. They are seen or only partially encapsulated. They are seen within 4 weeks in necrotizing pancreatitis.within 4 weeks in necrotizing pancreatitis.

• PseudocystPseudocystAfter 4 weeks in interstitial pancreatitis. After 4 weeks in interstitial pancreatitis. This fluid collection is encapsulated. Most This fluid collection is encapsulated. Most persistent fluid collections also contain persistent fluid collections also contain some necrotic material.some necrotic material.

• WONWONAfter 4 weeks most necrotic collections After 4 weeks most necrotic collections are fully encapsulated, heterogenous are fully encapsulated, heterogenous non_liquefied material and are called non_liquefied material and are called Walled-off Necrosis (WON).Walled-off Necrosis (WON).

CHRONIC CHRONIC PANCREATITISPANCREATITIS

• Chronic pancreatitis occurs due to Chronic pancreatitis occurs due to intermittent pancreatic inflamation with intermittent pancreatic inflamation with progressive irreversible dilation to the progressive irreversible dilation to the glandgland

• Alcholoism is the most common etiologyAlcholoism is the most common etiology• HALL MARK imaging feature: ductal HALL MARK imaging feature: ductal

dilation along with calcificationsdilation along with calcifications• Other featurs areatrophic gland, focal Other featurs areatrophic gland, focal

necrosis ascites and pleural effusion necrosis ascites and pleural effusion formationformation

• Pseudocysts are Pseudocysts are more common in more common in chronic thaan in chronic thaan in acute pancreatitis.acute pancreatitis.

• xray: calcifications xray: calcifications can be visualised can be visualised in half of the in half of the patients wth patients wth alcohol etiologyalcohol etiology

Ultrasound picture shows Ultrasound picture shows calcificationscalcifications

ulul

GROOVE PANCREATITISGROOVE PANCREATITIS• Distinct form of chronic pancreatitis Distinct form of chronic pancreatitis

affecting groove between pancreatic affecting groove between pancreatic head, duodenum and CBD.head, duodenum and CBD.

• CT: plate like hypoattenuating lesion CT: plate like hypoattenuating lesion located between pancreatic head located between pancreatic head and decending part of duodenum.and decending part of duodenum.

• MRCP: hypovascular lesion and MRCP: hypovascular lesion and pathognomic cystic changespathognomic cystic changes

AUTO IMMUNEAUTO IMMUNE• Another distinct form of chronic pancreatitisAnother distinct form of chronic pancreatitis• Typically affects patients without a history Typically affects patients without a history

of alcohol abuse and biliary stone disease.of alcohol abuse and biliary stone disease.• Gland shows infiltration by CD4 T Gland shows infiltration by CD4 T

lymphocytes and plasma cells.lymphocytes and plasma cells.• CT/MRI: Diffuse/focal gland enlargement CT/MRI: Diffuse/focal gland enlargement

Narrowing of Narrowing of pancreatic ductpancreatic duct

Delayed contrast enhancementDelayed contrast enhancement

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