Radioanatomy of biliary system

Radiological anatomy of hepatobiliary system.

1. RADIOANATOMY OF BILIARY SYSTEM DR. AKANKSHA MALVIYA JR-2 Department of Radiology SAIMS,Indore

2. DEVELOPMENT OF BILIARY APPARATUS 4 th week

3. PARTS OF BILIARY TREE

4. On Magnetic resonance cholangiopancreatography (MRCP)

5. On Endoscopic retrograde cholangiopancreatography ( ERCP ) 

6. ANATOMY OF BILIARY TREE Biliary tree is divided into: Intrahepatic ducts Extrahepatic ducts

7. INTRAHEPATIC DUCTS

8. has a variable drainage pattern but in majority, ducts.

9. Right and left hepatic ducts (short arrows) are normally seen lying anterior to the portal veins.

10. On ULTRASONOGRAPHY : Signs of Biliary Dilatation : Parallel Channel sign – IHBD > 2mm , CBD > 6mm  Post Fatty Meal Sonography : CBD size increase of 2mm Post Cholecystectomy : No compensatory dilatation of CBD, CBD > 10mm

11. Dilated Intrahepatic Biliary Ducts on CT Scan

12. EXTRAHEPATIC BILIARY APPARATUS The right and left hepatic ducts fuse at the hilum ,anterior to bifurcation of the portal vein to form Common Hepatic Duct which is then inserted by cystic duct from the gall bladder and becomes Common Bile Duct .

13. The CBD passes inferiorly posterior to the first part of duodenum and pancreatic head to enter the second part of duodenum along with the main pancreatic duct at Ampulla of Vater .

14. The picture above shows in better detail the Ampulla of Vater and its entrance into the common bile duct. The Ampulla of Vater and the Sphincter of Oddi are very close in location, remember that the sphincter of Oddi controls the opening of the ampulla of Vater , and is a separate entity.

15. Most commonly , the two ducts join in the duodenal wall and have a short common channel . Occasionally, separate orifices are present at the ampulla, or the ducts unite, forming a long common channel before entering the duodenal wall.

16. Common hepatic/common bile ducts of normal caliber in sagittal view lying in the typical position anterior to the portal vein and hepatic artery.

17. c) Mid and distal CBD in longitudinal view. Note the pancreas (*), the cranial margin of which demarcates the transition between suprapancreatic and intrapancreatic segments. d) Distal CBD and the ampulla of Vater (short arrow) are shown running posterior to the pancreatic head and inserting into the duodenum (D)

18. Intra and extra hepatic bile ducts on MRCP

19. GALL BLADDER Location : Epigastric region Right hypochondriac region On inferior surface of liver Between quadrate and right lobes . Pear‐shaped, hollow structure

20. Parts of gall bladder

21. Normal ultrasound of gall bladder

22. GALL BLADDER FOLDS LONGITUDINAL VIEW OF GALL BLADDER

23. Acoustic shadow from gb fold Part of a fold within gallbladder producing an acoustic shadow . When only part of fold is visualized, it may mimic a polyp or a stone.

24. Edge refraction shadow Shadow near neck of GB on longitudinal section. Absence of visible stone o the origin of shadow. Scan in different position .

25. Cystic Duct The gallbladder is attached to the common bile duct (CBD) via the cystic duct usually 2 to 4 cm long and contains tortuous folds, the spiral valves of Heister . Diameter 2-3 mm.

26. Proximal cystic duct

27. Distal cystic duct

28. Anatomic variants in the cystic duct.  Anatomic variants in the cystic duct. Drawings illustrate how the cystic duct may insert into the extrahepatic bile duct : right lateral insertion (A), anterior spiral insertion (B), posterior spiral insertion (C), low lateral insertion with a common sheath (D), proximal insertion (E), or low medial insertion (F).

29. Figure 1: Coronal oblique 3D MR cholangiopancreatography shows normal insertion of cystic duct at middle 3rd of common hepatic duct from lateral aspect (arrow).

30. Figure 2:  Coronal oblique 3D MR cholangiopancreatography shows spiral course of cystic duct (white arrow) with medial insertion with CHD. GB: gall bladder.

31. Figure 3: Coronal oblique 3D MR cholangiopancreatography shows low medial insertion of cystic duct where cystic duct (arrow) drains at lower 3rd of CHD from left side.

32. Figure 4: Coronal oblique 3D MR cholangiopancreatography shows parallel course of cystic duct (white arrow) and CHD (white arrowhead). Also note medial insertion of cystic duct (red arrow). GB: gall bladder.

33. Figure 5: Coronal oblique 3D MR cholangiopancreatography shows high insertion of cystic duct at upper 3rd of CHD from lateral aspect.

34. Figure 6: (a) Coronal oblique 3D MR cholangiopancreatography . shows short cystic duct with anterior insertion (arrow) into the CHD (arrowhead). GB: gall bladder.

35. Figure 7: Coronal oblique 3D MR cholangiopancreatography shows aberrant insertion of cystic duct (red arrow) into the right hepatic duct (white arrow) and low union of right and left hepatic duct (blue arrow). Also note multiple calculi (black arrow) in common bile duct (white arrowhead). A: right anterior sectoral duct, P: right posterior sectoral duct, RHD: right hepatic duct, LHD: left hepatic duct, CD: cystic duct, and GB: gall bladder.

36. ARTERIAL SUPPLY Three segments of supply.

37. DEVELOPMENTAL INTRAHEPATIC BILIARY ANOMALIES Right posterior duct (RPD) is in red .

38. EXTRAHEPATIC BILIARY ANOMALIES CLASSIFICATION OF GALL BLADDER ANOMALIES

39. AGENESIS OF GB 1 in 6,000 life births – fewer than 300 reported cases Agenesis Of The Gallbladder Agenesis of the gallbladder is caused by failure of development of the caudal division of the primitive hepatic diverticulum or failure of vacuolization after the solid phase of embryonic development. Other congenital anomalies are present in two thirds of these patients, including congenital heart lesions, polysplenia , imperforate anus, absence of one or more bones, and rectovaginal fistula. The surgical incidence of gall bladder agenesis is approx. 0.02%. 

40. There are two main expressions: 1) AGB without cystic duct remnant and 2) AGB with cystic remnant . Ultrasound or CT may suggest the diagnosis, but it is usually diagnosed at surgery when the gallbladder is not found at cholangiography.

41. AGENESIS OF GALL BLADDER

42. Absence of gallbladder and cystic duct on MRCP (blue arrow marks common bile duct).

43. Duplication Of The Gallbladder ( Vesica fellea duplex) 1 in 4000 people This anomaly is caused by incomplete revacuolization of the primitive gallbladder, resulting in a persistent longitudinal septum that divides the gallbladder lengthwise / occurrence of separate cystic buds. To establish the diagnosis, two separate gallbladder cavities, each with its own cystic duct, must be present. These duplicated cystic ducts may enter the common duct separately or form a Y-configuration before a common entrance. Most reported cases of gallbladder duplication have a clinical picture of cholecystitis with cholelithiasis in at least one of the gallbladders.

44. Duplicated gall bladder Picture courtesy : Dr. Sudheer Gokhale Sir, Mohak Hi-tech Speciality Hospital,Indore .

45. 3D Coronal MIP image of MRCP demonstrates duplication of gallbladder (stars) with two cystic ducts (arrow heads)  CT abdomen scan coronal (b) and sagittal (c) reformated sections show two separate cystic structures in gallbladder fossa. Superior and anteriorly placed normal inflamed gallbladder and the duplicated gall bladder (arrow) posteroinferior in position to the normal gallbladder.

46. The bilobed gallbladder ( Vesica fellea divisa) structure having two separate fundic cavities , united at their bases and joined to the ductus choledochus by a single cystic duct . It is differentiated from double/accessory GB by presence of independent cystic ducts, draining individual fundic cavities of the latter type. 

47. Wandering Gallbladder When the gallbladder has an unusually long mesentery , it can “wander” or “float.” A wandering gallbladder typically is attached to surrounding structures only by the cystic duct and its mesentery. Its characteristic propensity for torsion places it at risk for necrosis . The gallbladder may “disappear” into the pelvis on upright radiographs or wander in front of the spine or to the left of the abdomen. Rarely, the gallbladder can herniate through the foramen of Winslow into the lesser sac. The herniation can be intermittent and may be responsible for abdominal pain.

48. Most cases of gallbladder torsion occur in women (F/M ratio of 3:1). The usual preoperative diagnosis is acute cholecystitis. Gangrene develops in more than 50% of cases and is extremely common when the pain has been present for more than 48 hours. On cross-sectional imaging, the gallbladder is distended and may have an unusual location and show mural thickening. Prone radiograph as a part of an oral cholecystogram reveals the opacified gallbladder (curved arrow) to Lie in the left upper pelvis. This excessive mobility represents a "wandering gallbladder."

49. Computerized tomography showing a low-lying gallbladder (white arrow) and a horseshoe kidney. Figure 1: Reconstructed coronal images on computed tomography demonstrating the dilated and relatively inferiorly placed gallbladder.Acute gastric distension was also present due to duodenal compressionby the very dilated gallbladder (not shown). Figure 2: Intraoperative view of gangrenous wandering gallbladder (G) completely separate from the liver (L) and torted clockwise around the cystic duct and mesentery (C).

50.  Anomalous location / ectopic gallbladderRare – Reported only in isolated case reports Most common locations • Left side (posterior to left lobe) • Intrahepatic • Suprahepatic (right lobe & diaphragm) • Retrohepatic (posterior to right lobe) Intrahepatic gall bladder

51. Multi-septate gallbladder Congenital origin – Very rare Entire GB or part of lumen Chambers communicate by orifices Isolated or coexist with other anomalies Symptoms of recurrent cholecystitis Multiple linear fine echogenic septations- Oriented horizontally or vertically

52. True diverticulum of gallbladder Extreme rarity Occurs anywhere in GB Usually singleVaries greatly in size  Congenital diverticula are true diverticula and contain all the mural layers, as opposed to the pseudodiverticula of adenomyomatosis , which have little or no smooth muscle in their walls. 

53. True diverticulum of gallbladder

54. Choledochal Cysts Choledochal cysts are congenital cystic dilatations of any portion of extra hepatic bile ducts , most commonly the main portion of CBD . It is postulated that this condition begins with an anomalous junction of the common bile duct and pancreatic duct proximal to the duodenal papilla. Higher pressure in pancreatic duct combined + an absent ductal sphincter allows free reflux of enzymes into biliary tree, weakening wall of the common bile duct.

55. Diagnosis of a choledochal cyst is made on the basis of disproportional dilatation of the extrahepatic bile ducts after excluding the possibility of a tumor, stone, or inflammation as the cause of the dilatation. The estimated incidence of choledochal cysts in Western countries varies between 1 in 100,000 and 1 in 150,000 individuals. 60% of patients present before age 10, although choledochal cysts can present from birth to old age. This anomaly is associated with increased incidence of GB anomalies, biliary anomalies ( stenosis /atresia), and congenital hepatic fibrosis. Complications of choledochal cysts in adults include rupture with bile peritonitis, secondary infection (cholangitis), biliary cirrhosis and portal hypertension, calculus formation, portal vein thrombosis, liver abscess, hemorrhage, and malignant transformation into cholangiocarcinoma .

56. Todani classification

57. Type-1 choledochal cyst on usg

58. Presentation Neonatal jaundice Patient Data AGE:  15 months GENDER:  Female Choledochal cyst with dilated bile ducts in left and right liver lobes.

59. Caroli’s Disease Caroli’s disease, also known as communicating cavernous ectasia , is characterized by multifocal segmental saccular dilatation of the intrahepatic bile ducts, a predisposition to biliary calculi and cholangitis, and an association with various forms of cystic renal disease. It is an autosomal recessive disease secondary to the ductal plate malformation. It is associated with polycystic kidney disease, medullary sponge kidney and medullary cystic disease. Caroli’s disease usually manifests in adulthood; however, it can be seen in newborns and infants. Adult patients present with recurrent attacks of cholangitis and crampy right upper quadrant pain with occasional fever and mild jaundice.

60. Infants and children may present with hematemesis caused by portal hypertension from hepatic fibrosis. Complications of Caroli’s disease include stone formation (95%) within the dilated intra-hepatic ducts, recurrent cholangitis, and liver abscess. There is also a 100-fold increase in incidence of bile duct carcinoma, occurring in 7% of patients. Caroli’s disease is best demonstrated by cholangiography which shows saccular dilatations of the intrahepatic ducts, stones, strictures, and communicating hepatic abscesses.

61. Ultrasound : May show dilated intrahepatic bile ducts (IHBD). intraductal bridging : echogenic septa traversing the dilatedbile duct lumen. small portal venous branches: partially/completely surrounded by dilated bile ducts. intraductal calculi .

62. CT : multiple hypodense rounded areas which are inseperable from the dilated intrahepatic bile ducts “ centraldot ” sign : enhancing dots within the dilated intrahepatic bile ducts, these intraluminal dots correspond to intraluminal portal veins. MRCP with three-dimensional display is an accurate method for demonstrating Caroli’s disease because the luminal contents of the bile ducts appear hyperintense in contrast to the portal vein, which usually appears as signal void . Cystic expansions of the intrahepatic biliary tract are depicted as oval- shaped structures in continuity with the biliary tract.

63. Biliary atresia Biliary atresia is a congenital biliary disorder, which is characterised by an absence or severe deficiency of the extra-hepatic biliary tree . It is one of the most common causes of neonatal cholestasis , often causing cirrhosis immediately and leading to death and accounts for over half of children who undergo liver transplantation. Incidence- 1 in 10,000-15,000 newborn infants. There is a recognized male predilection . Luminal obstruction of the extrahepatic bile duct with a fibrous ductal remnant is the pathology.

64. Infants with biliary atresia may appear normal & healthy at birth. Most often, symptoms develop between 2wks-2mnths, and may include : Jaundice Dark yellow or brown urine Pale or clay-colored (acholic) stools Hepatomegaly. Affected neonates have associated congenital defects, including situs inversus, polysplenia , malrotation, intestinal atresia, and cardiac anomalies.

65. Kasai Classification of biliary atresia

66. Ultrasound Echogenic triangular cord sign : Tubular echogenic cord of fibrous tissue seen in the porta hepatis at ultrasonography and is relatively specific in diagnosis of biliary atresia. It is defined as more than 4 mm thickness of echogenic anterior wall of right portal vein (EARPV) measured on a longitudinal ultrasound scan. Gallbladder ghost triad : Atretic gallbladder, length less than 19 mm Irregular or lobular contour Lack of smooth/complete echogenic mucosal lining with indistinct wall Larger hepatic arterial calibre

67. triangular cord sign

68. Anomalous Pancreaticobiliary Ductal Junction Found in all the patients of choledocal cyst, but not vice versa More commonly associated with cholangiocarcinoma Most Reliable method for diagnosis – ERCP

69. INVESTIGATION Radiological investigations comprise of : Plain radiograph Ultrasound Computed tomography Magnetic resonance imaging Radionuclide imaging Indirect cholangiography

70. Plain Radoigraph Plain radiograph is usually taken as part of sequence of investigation of abdominal pain. It gives information about radiopaque stones, mural calcification, mural gas and gas in biliary tree.

71. ULTRASOUND the first line investigation particularly calculous disease(over 98% accuracy). U/S detects dilated Intrahepatic and extrahepatic ducts, cholelithiasis, cholecystitis, GB polyp, choledochal cyst etc

72. ENDOSCOPIC ULTRASOUND (EUS) • This provides high-frequency grey-scale imaging (± colour Doppler) for the evaluation of the extrahepatic biliary tree, pancreas and duodenum ▸ it can also allow fine-needle aspiration cytology to be performed

73. COMPUTED TOMOGRAPHY The sensitivity of CT in differentiating hepatocellular from obstructive jaundice and in determining the level and cause of obstruction parallels that of ultrasound. CT is reserved for those patients in whom there is doubt as to the cause of obstruction and in staging of biliary tumours .

74. MAGNETIC RESONANCE CHOLANGIOPANCREATOGRAPHY (MRCP) Technique • Heavily T2-weighted coronal oblique fast spin-echo sequence to obtain source data (aligned along the plane of the common bile duct [CBD]) ■ Stationary water appears as areas of high SI and adjacent soft tissue is low SI (therefore it is not reliant on contrast excretion and can be used in jaundiced patients) ■ Fasting reduces any unwanted signal from the adjacent intestine • Source data allows MIP reformats to be generated (highlighting fluid-filled structures) – usually a number of coronal MIP reformats over 180° • Secretin: this stimulates exocrine pancreatic secretion, distending the pancreatic duct and improving its visualization (acts immediately, returning to baseline at 10 min) ■ Uses: liver donor transplant work-up ▸ the assessment of bile leaks and biliary communication with cysts ▸ the demonstration of segmental obstruction

75. HEPATOBILIARY SCINTIGRAPHY • Hepatobiliary iminodiacetic acid (HIDA) scintigraphy: this is a bilirubin analogue labelled with 99mTc ■ It is injected intravenously with serial images obtained over 2–4 h (it requires near-normal bilirubin levels) • There is normally accumulation of isotope within liver, bile ducts, gallbladder, duodenum and small bowel by 1 hr ■ Delayed hepatic activity: hepatocellular disease (with corresponding elevated bilirubin levels) ■ Non-demonstration of the gallbladder: acute cholecystitis ▸ a contracted gallbladder (e.g. following a recent meal)

76. Hida scan

77. ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY (ERCP) • This allows direct bile and pancreatic duct opacification, as well as visual assessment of the duodenum and ampulla of Vater ■ It also allows for: biopsy ▸ brushings ▸ sphincterotomy ▸ stone extraction ▸ biliary stenting ▸ biliary stricture dilatation • The main complication is the precipitation of pancreatitis • The main pitfall is the presence of underfilled ducts above a stricture

78. INDIRECT CHOLANGIOGRAPHY / ORAL CHOLANGIOGRAPHY It has a limited role in anatomical and functional assessment of gall bladder but the diagnostic accuracy in demonstrating gall stones is upto 90%. The media commonly used is sodium ipodite ( Biloptin ),Calcium ipodite ( Solubiloptin ).

79. PERCUTANEOUS CHOLANGIOGRAPHY (PTC) Direct puncture of the intrahepatic ducts using a fine-gauge Chiba needle allows demonstration of biliary tree with relative safety. INDICATIONS Obstructed jaundice with or without duct dilatation. In defining biliary-enteric or biliary-cutaneous fistulas. In defining levels of bile leak. To map biliary tree as a preliminary to establish external or internal biliary drainage with stent placement.

80. Percutaneous transhepatic cholangiography

81. OPERATIVE CHOLANGIOGRAPHY Operative cholangiography prior starting surgical procedure is done commonly at the time of cholecystectomy for: Exploration of CBD Anomalous duct anatomy Developmental disorders of biliary tree. Postoperative cholangiography through a T-tube is indicated to ensure removal of all stones.

82. T-tube cholangiography

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