PANCREATIC ANOMALY radiology.pptx

PANCREATIC ANOMALY radiology

1. D R. SABHILASH SUGATHAN CONGENITAL ANOMALIES OF PANCREAS Mortelé KJ, Rocha TC, Streeter JL, Taylor AJ. Multimodality imaging of pancreatic and biliary congenital anomalies. RadioGraphics 2006;26(3):715–731. Anomalies, Anatomic Variants, and Sources of Diagnostic Pitfalls in Pancreatic Imaging by Peyman Borghei MD , Farnoosh Sokhandon MD , Ali Shirkhoda MD , Desiree E. Morgan MD 10.1148/radiol.12112469

2. The  pancreas  is a  retroperitoneal  organ that has both endocrine and exocrine functions: it is involved in the production of hormones ( insulin ,  glucagon , and  somatostatin ), and also involved in digestion by its production and secretion of pancreatic enzymes. Long (around 15cm ) epigastric structure extending from duodenal loop to splenic hilum Comprises the head (including uncinate process), neck, body and tail.

3. GROSS ANATOMY The pancreas may have the shape of a dumbbell, tadpole, or sausage.  It can be divided into four main parts: HEAD : thickest part; lies to the right of the mesenteric vessels uncinate process: extension of the head, posterior to SMV, SMA  attached to "C" loop of  duodenum  (D2 and D3) NECK : thinnest part; lies anterior to SMA, SMV SMV joins  splenic vein  behind pancreatic neck to form portal vein BODY : main part; lies to left of SMA, SMV splenic vein lies in groove on posterior surface of body TAIL : lies between layers of the  splenorenal ligament  in the splenic hilum

4. GROSS ANATOMY The normal arrangement is for the entire pancreas to be drained via a single duct, to the  ampulla of Vater  through the  sphincter of Oddi .

5. MAIN PANCREATIC DUCT portion of the dorsal duct proximal to the dorsal-ventral fusion point drains at the ampulla of Vater connects with the accessory pancreatic duct (of Santorini) (see below) if present

6. ACCESSORY PANCREATIC DUCT (OF SANTORINI OR BERNARD) portion of the dorsal duct distal to the dorsal-ventral fusion point  drains anterior and superior portion of the head in 70% of individuals drains to the minor papilla in 30% of individuals persists as a branch of the main pancreatic duct

7. Pancreatic duct of Wirsung distal portion of the main pancreatic duct segment of the ventral duct   between the dorsal-ventral fusion point and the major papilla continuous with the main pancreatic duct proximally joins with the common bile duct at a 60 degree angle at the hepatopancreatic ampulla.

8. EMBRYOLOGICAL DEVELOPMENT By the 4th week of embryologic development, the pancreatic duct develops from separate ventral and dorsal buds originating from the endodermal lining of the duodenum. The gallbladder, extrahepatic bile ducts, central intrahepatic bile ducts, and ventral pancreas with its ductal network are derived from the ventral bud or outpouching. The dorsal bud is the precursor to dorsal pancreas and its ductal system . The ventral pancreas rotates clockwise posterior to the duodenum and comes into contact with the dorsal pancreas in the 7th gestational week to develop into the future pancreatic neck. The dorsal and ventral pancreatic buds grow into a pair of branching , arborizing ductal systems . After fusion, a new duct connects the distal portion of the dorsal pancreatic duct with the shorter duct of the ventral pancreas to form the main pancreatic duct, also known as the duct of Wirsung , which empties into the major papilla. The remnant of the dorsal duct forms the duct of Santorini, which drains into minor papilla

9. Dorsal pancreatic bud develops into the anterior part of the head, body, and tail (and a small variable portion of the uncinate process) contains a long duct continuing from the accessory pancreatic papilla to the tail

10. Ventral pancreatic bud smaller of the two buds that develops into the posterior part of the pancreatic head and most of the uncinate process contains a short main pancreatic duct which is connected to the common bile duct develops just distal to the developing biliary tree starts to the right of the duodenum rotates to the left underneath the dorsal pancreas

11. VARIANT ANATOMY Annular pancreas Fishtail pancreas Ectopic pancreatic tissue Horseshoe pancreas pancreatic duct variations pancreatic clefts : linear clefts may be seen which contain fat where small vessels enter the pancreas and are a common mimic of  pancreatic laceration . They are most prominent at the junction of the body and neck 

12. ANNULAR PANCREAS pancreatic tissue completely or incompletely encircling the  duodenum

13. Clinical presentation annular pancreas in adults are asymptomatic and an incidental finding on imaging. However, it can cause pancreatitis, duodenal obstruction and rarely biliary obstruction.  In children, an annular pancreas may be associated with other congenital anomalies or cause duodenal obstruction.

14. EMBRYOLOGY The pancreas develops from a single dorsal and two ventral buds, which appear as outgrowths of primitive foregut at 5 weeks of gestation. The ventral buds fuse rapidly. In the 7 th  week of gestation, the  duodenum  expands and rotates the ventral bud from right to left which then fuses with the dorsal bud. The ventral bud forms the inferior part of uncinate process and inferior head of  pancreas  while the dorsal bud gives rise to the tail and body of pancreas. Annular pancreas develops due to failure of the ventral bud to rotate with the duodenum, causing encasement of the duodenum.

15. CLASSIFICATION complete annular pancreas:   pancreatic parenchyma or an annular duct is seen to completely surround the 2 nd  part of duodenum incomplete annular pancreas:   annulus does not surround the duodenum completely, giving a 'crocodile jaw' appearance

16. Pancreatic tissue surrounds the duodenum

17. RADIOGRAPHIC FEATURES CT Pancreatic tissue is seen to completely or incompletely surround the 2 nd  part of the duodenum. Associated duodenal narrowing and dilatation of the proximal duodenum may also be seen. In adults, it is frequently associated with  pancreatitis . MRI/MRCP Apart from annular pancreas features,  pancreatic ductal anatomy  can be well assessed with MR imaging.

18. There is an 'echogenic focus' in short-axis images of the pancreas head The structure in the head of the pancreas is the 2nd part of the duodenum incomplete annular pancreas

19. Upper gastrointestinal radiograph of annular pancreas shows slit-like smooth narrowing of the second portion of duodenum (arrows). No gastric distention or mechanical obstruction is present. Contrast material flows freely into an otherwise normal duodenum and proximal jejunum.

20. Unenhanced axial CT scan of annular pancreas in 43-year-old man with history of resected glucaconoma in the pancreatic tail. The pancreatic tissue encircles the positive oral contrast material–filled second portion of the duodenum(arrows), making the anomaly easy to recognize even without intravenous contrast material.

21. Intravenous contrast-enhanced axial CT scan of annular pancreas normal enhancing pancreatic tissue (arrows) surrounding the collapsed duodenum. The patient received water as a negative oral contrast agent. Wirsung duct of the ventral pancreas (arrowhead) is draining into duodenum.

22. ERCP spot image of annular pancreas in 43-year-old man shows mild diffuse acinarization of the pancreas (solid arrows). The pancreatic tissue and pancreatic duct (arrowhead) are to the right of the second portion of the duodenum, consistent with annular pancreas. Focal dilatation of the main pancreatic duct (dashed arrow) with pooling of contrast material in the dependent portion is also present.

23. Treatment and prognosis In symptomatic cases of annular pancreas, surgical management is the treatment of choice. Bypass surgeries such as duodeno -jejunostomy or gastro-jejunostomy are the mainstay of surgical management  3 . 

24. FISHTAIL PANCREAS Fishtail pancreas  (also known as  pancreas bifidum  or  bifid tail of the pancreas ) is a rare  anatomical variant  of the  pancreas  produced by a branching anomaly during its development. It is named as such due to the fishtail-like appearance of the pancreas.

25. Fishtail pancreas is thought to be caused by the failure of part of the ventral pancreatic  anlage  to regress. The ventral pancreatic anlage develops into the majority of the pancreatic gland. During pancreatic development, the ventral anlage initially has two lobes with two primitive ducts .   One lobe tends to dominate and persists to become the head of the pancreas, while the other regresses and becomes the uncinate process of the pancreas. Fishtail pancreas is caused by failure of one of these lobes to regress producing duplication of the main pancreatic duct creating a dorsal and ventral tail .

26. RADIOGRAPHIC FEATURES MRCP Fishtail pancreas may be visible as a duplication of the major duct in the body of the pancreas and the presence of two pancreatic tails . ERCP Like MRCP, on ERCP it also shows duplication of the major pancreatic duct 

27. ECTOPIC PANCREATIC TISSUE Ectopic pancreatic tissue , aka heterotopic pancreatic tissue , refers to the presence of  pancreatic tissue   in the submucosal, muscularis or subserosal layers of the luminal  gastrointestinal tract   outside the normal confines of the  pancreas   and lacking any anatomic or vascular connection with the pancreas proper.

28. Location proximal  duodenum gastric antrum   proximal jejunum Meckel diverticulum ileum

29. Radiographic features On upper gastrointestinal examination, an ectopic pancreas appears as an extra- mucosal, smooth, broad-based lesion either along the greater curvature of the gastric antrum or in the proximal duodenum. 1. Fluoroscopy 2. Upper GI barium study In 45% of the cases of ectopic pancreas discovered on  upper gastrointestinal fluoroscopic examination , the ectopic pancreatic tissue contained a central small collection of  barium , i.e. a central niche or umbilication , indicative of the rudimentary duct’s draining orifice ​. It is this finding that is diagnostic of ectopic pancreatic tissue.

30. Heterotopic pancreas in the gastric antrum with central umbilication . Fluoroscopic images 

31. Ectopic pancreatic tissue ( green arrows ) similar to attenuation of the pancreas ( red arrow ) in all 3 phases. 3. CT Contrast enhanced CT may show a homogeneously enhancing tissue (similar to normal pancreas) or cystic area (acinar component or pseudocyst).

32. HORSESHOE PANCREAS A rare anatomic variant of the  pancreas  in which the  uncinate process   is unusually elongated such that it extends along the whole  3rd part of the duodenum   to mirror the tail superiorly forming a horseshoe-shaped gland .

33. The uncinate process of the pancreas extends along the entire aspect of the third part of the duodenum . Normal anatomic variant of horseshoe pancreas.

34. PANCREAS DIVISUM Pancreas divisum  represents a  variation in pancreatic ductal anatomy   that can be associated with abdominal pain and idiopathic  pancreatitis . It is characterized, in the majority of cases, by the main  pancreatic duct   directly entering the minor papilla with no communication with the ventral duct the major papilla. I t results from failure of fusion of dorsal and ventral pancreatic anlages . As a result, the dorsal pancreatic duct drains most of the pancreatic glandular parenchyma via the minor papilla. Although controversial, this variant is considered a cause of pancreatitis. 

35. Three subtypes are known: TYPE 1 (CLASSIC):   no connection at all; occurs in the majority of cases; 70%  TYPE 2 (ABSENT VENTRAL DUCT):   minor papilla drains all of pancreas while major papilla drains bile duct; 20-25%  TYPE 3 (FUNCTIONAL):   filamentous or inadequate connection between dorsal and ventral ducts; 5-6% Anomalies, Anatomic Variants, and Sources of Diagnostic Pitfalls in Pancreatic Imaging by Peyman Borghei MD , Farnoosh Sokhandon MD , Ali Shirkhoda MD , Desiree E. Morgan MD 10.1148/radiol.12112469

36. TYPE 1 (CLASSIC):   no connection at all; occurs in the majority of cases; 70% 

37. TYPE 2 (ABSENT VENTRAL DUCT):   minor papilla drains all of pancreas while major papilla drains bile duct; 20-25% 

38. TYPE 3 (FUNCTIONAL):   filamentous or inadequate connection between dorsal and ventral ducts; 5-6%

39. RADIOGRAPHIC FEATURES 1. Fluoroscopy 2. ERCP This was the traditional method of diagnosis where a pancreas divisum was suspected when there was no contrast extending towards the pancreatic tail when administered through the  ampulla of Vater . 3. MRI MRI is the current gold standard method of evaluation. The key imaging features: the dorsal pancreatic duct is in direct continuity with the duct of Santorini, which drains into the minor papilla the ventral pancreatic duct (duct of Wirsung ) does not communicate with the dorsal pancreatic duct but joins with the distal common bile duct to enter the major papilla I ncreased sensitivity of  secretin MRCP  (S-MRCP) in detection of pancreas divisum  .

40. CT PANCREATIC DIVISUM

41. MRCP image of pancreas divisum the main pancreatic duct (dorsal Santorini duct, straight solid arrow) draining separately into the minor papilla (dashed arrow). The common bile duct (arrowheads) joins the smaller ventral pancreaticduct (curved arrow) at a more inferior leveland drains into the duodenum through the major papilla. Figure 3

42. ERCP images of pancreas divisum . (a) The main pancreatic duct (arrows) drains through the minor papilla, consistent with pancreas divisum . (b) The short, terminally arborizing duct of Wirsung (arrow) is depicted by means of contrast material injection of the major papilla , with the common bile duct (arrowhead) also filling.

43. Reverse pancreas divisum :   has been described where the main duct fuses with the ventral duct and a small residual dorsal duct does not communicate with the main duct and drains separately into the minor papilla.

44. TREATMENT AND PROGNOSIS A diagnosis of pancreas divisum does not routinely warrant treatment, especially when incidental and asymptomatic. In symptomatic patients (e.g. recurrent pancreatitis), management options may include: conservative, non-operative treatment +/- pancreatic enzyme supplements minor papillotomy minor papilla stenting balloon dilatation of any associated stricture

45. VARIATIONS OF PANCREATIC DUCT

46. ANOMALOUS PANCREATICOBILIARY JUNCTION An  anomalous pancreaticobiliary junction , also known as  pancreaticobiliary maljunction , describes the abnormal junction of the  pancreatic duct  and  common bile duct  that occurs outside the  duodenal  wall to form a long common channel (>15 mm)  .

47. The origin of a long common channel might be formed embryologically with adhesion of the ventral pancreatic duct and the terminal portion of the bile duct .  It is divided into anomalous pancreaticobiliary junction with biliary dilatation (77%) and without biliary dilatation (23%) . The anomalous pancreaticobiliary junction makes biliary drainage not under the control of  sphincter of Oddi , resulting in pancreatic juice reflux into the biliary tract that injures the biliary epithelium .

48. CLASSIFICATION The Japanese Study Group on Pancreaticobiliary Maljunction (JSPBM) proposed the following classification in 2015: TYPE A (STENOTIC TYPE):   dilatation of the common bile duct upstream of a stenotic segment of the distal common bile duct, which joins the common channel

49. TYPE B (NON‐STENOTIC TYPE):   nonstenotic distal common bile duct smoothly joins the common channel; no localized dilatation of the common channel

50. TYPE C (DILATED CHANNEL TYPE):   narrow distal common bile duct joins dilated common channel

51. TYPE D (COMPLEX TYPE):   complex maljunction associated with  annular pancreas ,  pancreas divisum , or other complicated duct systems

52. Anomalous pancreaticobiliary Junction   with dilated common channel (type c).

53. pancreaticobiliary maljunction type a (stenotic type)

54. RADIOGRAPHIC FEATURES ERCP An intrabiliary amylase level more than 8000 UI/L within the bile duct and gallbladder obtained endoscopically (ERCP) or percutaneously suggests reflux of pancreatic juice through an anomalous pancreaticobiliary junction and shows a positive predictive value and a specificity of more than 90 % .  In patients with a short common channel, direct cholangiography (e.g.  ERCP ) can be effective in the assessment of pancreaticobiliary junction incompetence.

55. Ultrasound It has a limited role in diagnosis , but is a useful noninvasive tool for screening . Careful measurement of the common bile duct and comparison with the normal limits for age helps in early detection. Detection of a dilated common bile duct may be the first clue to suspect pancreaticobiliary maljunction with biliary dilatation. In this case, further  MRCP  is recommended for biliary junction anatomy. It is also associated with gallbladder wall thickening. However, it is non-specific. The visualization of pancreaticobiliary junction outside the duodenal wall can be detected at  endoscopic ultrasound . It is also helpful in screening and surveillance of biliary cancer after diagnosis of pancreaticobiliary maljunction

56. CT/MRI a common channel length of >8 mm an abnormal union between the pancreatic and bile ducts pancreaticobiliary junction outside the duodenal wall common bile duct dilatation is suggestive of pancreaticobiliary maljunction with biliary dilatation MRCP  is the  gold standard  of diagnosis and is superior to ERCP in depicting biliary anatomy, including the intrahepatic bile duct.

57. ANSA PANCREATICA It is a communication between the  main pancreatic duct  (of Wirsung ) and the   accessory pancreatic duct   (of Santorini).  Recently, the ansa pancreatica has been considered as a predisposing factor in patients with idiopathic  acute pancreatitis   . The ansa pancreatica arises as a branch duct from the main pancreatic duct. It descends down initially, it then ascends upward forming a loop finally terminating at the minor papilla. This type of pancreatic ductal variation can be identified on  ERCP  or  MRCP  studies.

58. The main pancreatic duct (of Wirsung ) enters the duodenum in the conventional location at the major ampulla with the CBD.  The duct  (of Santorini) draining the uncinate process enters the duodenum proximally at the minor ampulla.  An abnormal duct joins the main pancreatic duct in the region of the head to the minor ampulla - this is known as ansa pancreatica (i.e. the handle of the pancreas - this accessory duct looking like a handle)

59. The branch duct (' ansa pancreatica ') arises from the main pancreatic duct, and loops inferiorly to before terminating in the minor papilla. In this case, the side branches of the duct are dilated adjacent to the minor papilla. This patient also has congenital absence of the gallbladder (gallbladder agenesis).

60. ERCP image of ansa pancreatica Dashed line represents dorsal main pancreatic duct (technically underfilled). There is obliteration of the proximal dorsal pancreatic duct(solid arrow). The proximal dorsal duct connects with an inferior branch of the ventral duct (arrowhead) through S-shaped collateral (dashed arrow).

61. PANCREATIC CYSTS A congenital true pancreatic cyst is a very rare entity, mostly seen in children younger than 2 years of age These cysts develop as a result of sequestration of primitive pancreatic ducts and are lined by cuboidal epithelium Congenital pancreatic cysts are generally asymptomatic, although abdominal distention, vomiting, jaundice, or pancreatitis can be observed At imaging, this condition manifests as a uniform thin-walled cyst usually in the region of the pancreatic body and tail Congenital true pancreatic cysts may be idiopathic or may be observed in association with other systemic diseases such as Von Hippel– Lindau disease , Beckwith- Wiedeman syndrome, or polycystic disease of the pancreas and kidneys

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