Anatomy of hepatobillary system dr avinash with cbd.pptx

Brief radiological anatomy of hepatobillary system.
Information about the congenital anomalies seen in Ultrasound has been discussed.The slide starts with the development of hepatobillary system and it mainly focused on radiological anatomy useful in ultrasound.

1. Anatomy of hepatobillary system Dr Avinash kumar singh First year resident Department of radiodiagnosis Nepalgunj medical college and teaching hospital

2. Anatomy of hepatobillary system Dr Avinash kumar singh First year resident Department of radiodiagnosis Nepalgunj medical college and teaching hospital

3. Development of hepatobillary system Liver primordium: third week out growth of endodermal epithelium (hepatic diverticulum or liver/hepatic bud from the ventral aspect at the distal end of foregut,just at its junction with the midgut. Hepatic bud consist of rapidly proliferating cells that grows into ventral mesogastrium and through it into the septum transversum. Buds divides into two parts : large cranial part-pars hepatica (liver) and small caudal part- pars cistica (GB and cystic duct) Part of duct proximal to pars cystica forms CBD

4. The sources of liver 1. parenchyma of liver: from endodermal hepatic bud of foregut. 2.fibrous stroma of liver: from mesenchyme of septum transversum. 3.sinusoids of liver: from absorbed and broken vitelline and umbilical veins with the septum transversum.

5. Development of gallbladder and extrahepatic biliary apparatus Gall bladder and cystic duct: develops from pars cystica Part of hepatic bud proximal to pars cystica forms CBD. Initially the CBD/bile duct opens on the ventral aspect of developing duodenum. As the duodenum rotates, opening of CBD is carried to dorsomedial aspect of the duodenum along with pancreatic bud.

6. Liver anatomy Liver is dived into segment by three major fissure and three minor fissure Cantle’s line –main fissure dividing liver into functional lobes right and left lobes. It is formed by line joining IVC and gallbladder fossa. The right lobe of liver is further divided into anterior and posterior by right intersegmental fissure The left lobe of liver is divided into medial and lateral by left intersegmental fissure.

7. Caudate lobe The caudate lobe is situated on the posterior aspect of the liver, with the IVC as its posterior border and the fissure for the ligamentum venosum as its anterior border

8. Enlarged caudate lobe Caudate is enlarged when the caudate to right lobe ratio is >0.65

9. Understanding the vascular anatomy of the liver is essential to an appreciation of the relative positions of the hepatic segments The major hepatic veins course between the lobes and segments (interlobar and intersegmental). The middle hepatic vein courses within the main lobar fissure and separates the anterior segment of the right lobe from the medial segment of the left. The right hepatic vein runs within the right intersegmental fissure and divides the right lobe into anterior and posterior segments

10. Portal vein define the segments Feed the segments Define the segments Name the segments

11. Division of main portal vein On coronal scan divides the liver into superior and inferior On axial scan divides the liver into anterior and posterior.

12. Porta hepatis

13. Couinaud Anatomy There are eight segments. The right, middle, and left hepatic veins divide the liver longitudinally into four sections. Each of these sections is further divided transversely by an imaginary plane through the right main and left main portal pedicles. This description is based on portal segments and is of both functional and pathologic importance

14. Ligaments of liver The liver is covered by a thin connective tissue layer called the Glisson capsule. The capsule surrounds the entire liver and is thickest around the IVC and the porta hepatis. At the porta hepatis, the main portal vein, the proper hepatic artery, and the common bile duct are contained within investing peritoneal folds known as the hepatoduodenal ligament. Falciform ligament : sickle shaped,extends from anterior abdominal wall to anterior surface of liver. The falciform ligament conducts the umbilical vein to the liver during fetal development After birth, the umbilical vein atrophies, forming the ligamentum teres . As the falciform ligament reaches the liver, its leaves separate. The right layer forms the upper layer of the coronary ligament; the left layer forms the upper layer of the left triangular ligament.

15. 2. Coronary ligament:connects the bare area of liver to diaphragm 3.Right triangular ligament: connects right lateral surface of liver to diaphragm. 4. Left triangular ligament: connects upper surface of left lobe of liver to diaphragm.

16. Normal Liver Size and Echogenicity The upper border of the liver lies approximately at the level of the fifth intercostal space at the midclavicular line. The lower border extends to or slightly below the costal margin. An accurate assessment of liver size is difficult with real-time ultrasound equipment because of the limited field of view. In 75% of patients with a liver length of greater than 15.5 cm, hepatomegaly is present.

17. Echogenicity of liver The normal liver is homogeneous, contains fine-level echoes, and is either minimally hyperechoic or isoechoic compared to the normal renal cortex . The liver is hypoechoic compared to the spleen. This relationship is evident when the lateral segment of the left lobe is elongated and wraps around the spleen. Renal medulla<renal cortex<liver Liver < spleen Liver < pancreas Pancreas < renal sinus and retro fat

18. Developmental anomalies Agenesis of liver Agenesis of the liver is incompatible with life. Agenesis of either the right or left lobes has been reported. In three of five reported cases of agenesis of the right lobe, the caudate lobe was also absent. Compensatory hypertrophy of the remaining lobes normally occurs, and results of liver function tests (LFTs) are normal.

19. Anomalies of Position In situs inversus totalis ( viscerum ), the liver is found in the left hypochondrium. In congenital diaphragmatic hernia or omphalocele, varying amounts of liver may herniate into the thorax or outside the abdominal cavity.

20. Vascular anomalies The common hepatic artery arises from the celiac axis and divides into right and left branches at the porta hepatis. This classic textbook description of the hepatic arterial anatomy occurs in only 55% of the population. The remaining 45% have some variation of this anatomy, the main patterns of which are: 1. replaced left hepatic artery originating from the left gastric artery (10%); 2. replaced right hepatic artery originating from the superior mesenteric artery (11%); and 3. replaced common hepatic artery originating from the superior mesenteric artery (2.5%).

21. Portal vein variants The most common variants of portal vein include trifurcation of the main portal vein. Right posterior segmental branch arising from the main portal vein Right anterior segmental branch arising from the left portal vein.

22. Portal vein anomalies Congenital portal vein anomalies include atresias , strictures, and obstructing valves, all of which are uncommon. Other variations of anatomy include absence of the right portal vein, with anomalies of branching from the main and left portal veins, and absence of the horizontal segment of the left portal vein.

23. Variants of hepatic vein Variations in the branching of the hepatic veins and accessory hepatic veins are common. The most common accessory vein drains the superoanterior segment of the right lobe (segment VIII) and is seen in approximately one-third of the population. It usually empties into the middle hepatic vein, although occasionally it joins the right hepatic vein. An inferior right hepatic vein, which drains the inferoposterior portion of the liver (segment VI) is observed in 10% of individuals. This inferior right hepatic vein drains directly into the IVC and may be as large as the right hepatic vein or larger

24. Left and right marginal veins, which drain into the left and right hepatic veins, occur in about 12% and 3% of individuals, respectively. Absence of the main hepatic veins is relatively less common, occurring in about 8% of people.

25. CONGENITAL ABNORMALITIES Liver Cyst A liver cyst is defined as a fluid-filled space with an epithelial lining. Abscesses, parasitic cysts, and posttraumatic cysts, therefore, are not true cysts. The frequent presence of columnar epithelium within simple hepatic cysts suggests they have a ductal origin, although their precise cause is unclear. Their presentation at middle age is also unclear. Sonographically visualized liver cysts occur in 2.5% of the general population, increasing to 7% in the population older than 80 years.

26. On sonographic examination, benign hepatic cysts are Anechoic with a thin, well-demarcated wall and posterior acoustic enhancement

27. Peribiliary Cysts Peribiliary cysts have been described in patients with severe liver disease. These cysts are small, 0.2-2.5 cm, and are usually located centrally within the porta hepatis or at the junction of the main right and left hepatic ducts. They generally are asymptomatic but in rare cases can cause biliary obstruction. Pathologically, peribiliary cysts are believed to represent small, obstructed periductal glands. Sonographically , they may be seen as discrete, clustered cysts or as tubular-appearing structures with thin septae , paralleling the bile ducts and portal veins.

28. Peribiliary cyst shown by arrow as string of cyst coursing parallel to portal vein  

29. Autosomal dominant polycystic kidney disease has liver cysts in 57% to 74% of patients. No correlation exists between the severity of the renal disease and the extent of liver involvement. Results of LFTs are usually normal and, unlike the autosomal recessive form of polycystic kidney disease, there is no association with hepatic fibrosis or portal hypertension. Indeed, if LFT results are abnormal, complications of polycystic liver disease, such as tumor, cyst infection, and biliary obstruction, should be excluded. Autosomal Dominant Polycystic Disease

30. Biliary Hamartomas (von Meyenburg Complexes) Bile duct hamartomas, first described by von Meyenburg in 1918, are small, focal developmental lesions of the liver composed of groups of dilated intrahepatic bile ducts set within a dense collagenous stroma. These benign liver malformations are detected incidentally in 0.6% to 5.6% of the autopsy series. Imaging features of von Meyenburg complexes (VMCs) include single, multiple, or, most often, innumerable well-defined solid nodules usually less than 1 cm in diameter. Nodules are usually uniformly hypoechoic and less frequently hyperechoic on sonography and Because of their multiplicity, they can be confused with metastatic cancer. Bright echogenic foci in the liver with distal comet tail artifact without obvious mass effect are key sonographic findings

31. BILIARY ANATOMY

32. Extrahepatic billary appratus Relationship of CBD Supraduodenal part of cbd posterior : IVC Portal vein anterior and left: proper hepatic artery Retrodeudenal part: Anterior: first part of duodenum Posterior: IVC, PV gastroduodenal artery Infraduoddenal part: Anterior : head of pancreas Posterior: IVC Left : portal vein

33. Yoshida classification

34. The cystic duct typically joins the common hepatic duct in the middle third of the extrahepatic bile duct—often referred to as the ‘common duct’ which then continues as the common bile duct (CBD) The cystic duct usually joins the right side of the common duct but can pass behind or in front of the common duct to join it from the left. The cystic duct is approximately 2-3 cm long and 2-3 mm in diameter

35. Variant anatomy There are three main variations of the cystic duct : low cystic duct insertion: into the distal-third of the CHD (~10%) medial cystic duct insertion: into the left, not the right, side of the CHD (~15%) parallel cystic duct course: courses parallel to the CHD for at least 2 cm (~10%)

36. Other variations include ducts of Luschka or subvesical ducts and cystohepatic ducts. ‘ Subvesical duct’ and ‘duct of Luschka’ both describe an intrahepatic duct running adjacent to the gallbladder fossa, unaccompanied by a portal vein branch, and emptying into either the right hepatic or common hepatic duct.

37. The term ‘cystohepatic duct’ is probably best reserved for small ducts that drain directly into the gallbladder or cystic duct. The significance of these variants is their proximity to the gallbladder and the potential for injury at cholecystectomy, resulting in a bile leak.

38. Gallbladder Anatomical Variants Agenesis of the gallbladder is extremely rare, with a prevalence of 0.03%–0.07% A double gallbladder occurs in about 0.03%, usually with a shared cystic duct, and the accessory gallbladder is often diseased.

39. The gallbladder may fold unto itself, the body onto the neck, or the fundus onto the body. The latter is called a phrygian cap and has no clinical significance.

40. A septate gallbladder is composed of two or more inter- communicating compartments divided by thin septa.

41. Billary anatomy An understanding of the normal location of the bile ducts and common anatomic variations is important in staging of malignancies and directing intervention. Biliary Terminology In biliary terminology, proximal denotes the portion of the biliary tree that is in relative proximity to the liver and hepatocytes, whereas distal refers to the downstream end closer to the bowel. The term branching order applies to the level of division of the bile ducts starting from the common hepatic duct (CHD)

42. first-order branches are the right and left hepatic ducts, second-order branches are their respective divisions (also known as secondary biliary radicles), and so on Central specifies proximity to the porta hepatis. Peripheral refers to the higher-order branches of the intrahepatic biliary tree extending well into the hepatic parenchyma. Most of the right and left hepatic ducts are extrahepatic and, along with the CHD, form the hilar or central portion of the biliary tree at the porta hepatis. This is the most common location for cholangiocarcinoma.

43. The normal diameter of the first-order and higher-order branches of the CHD has been suggested to be 2 mm or less and no more than 40% of the diameter of the adjacent portal vein.

44. Size of the duct The normal caliber of the CHD/CBD in patients without history of biliary disease is up to 6 mm in most studies. Although diameters of up to 10 mm have been recorded in an asymptomatic normal population, the great majority of the diameters are less than 7 mm. Therefore a ductal diameter of 7 mm or greater should prompt further investigations.

45. Normal variants of bile duct Common Variants of Bile Duct Branching. Right posterior duct (RPD) is highlighted in yellow. (A) RPD joins the right anterior duct in 56% to 58% of population. (B) RPD joins the left hepatic duct, 13%. (C) Trifurcation pattern, 8%. (D) RPD joins the common hepatic bile or cystic duct, 5%.

46. Choledochal Cysts (Congenital Biliary Dilatation) Choledochal cysts (also known as congenital biliary dilatation) represent a heterogeneous group of congenital diseases that may manifest as focal or diffuse cystic dilation of the biliary tree most patients present early in life, about 20% of choledochal cysts are encountered in adulthood, when sonography is performed for symptoms of gallstone disease.

47. Modified Todani system The Modified Todani Classification System for Choledochal Cysts. Type I cysts are single abnormalities. Type 1a represents saccular (spherical) dilation of the common bile duct (CBD); this is the most common type (80%). Type 1b is segmental dilatation of the CBD, whereas Type Ic is fusiform dilation of the entire CBD. Type II cyst: true diverticulum of the bile duct; very rare. Type III cyst: also called choledochocele ; diffuse dilation of the very distal (intraduodenal) CBD. Type IV cysts represent multifocal dilations of the bile ducts. Type IVa represents both intrahepatic and extrahepatic cysts Type IVb is multiple cysts of the extrahepatic duct only.

48. Type I. Cystic dilation of the common bile duct (CBD) is seen, but no obstructive lesion is noted Careful examination of the distal CBD using high-frequency linear transducer reveals a long common channel (arrow) between the CBD and pancreatic duct.

49. , Type II. A large diverticulum (arrow) is shown in figure arising from the common hepatic duct at the portal hepatis and containing mobile debris. Thick slab magnetic resonance cholangiopancreatography (MRCP) confirms the same. (

50. Type III. Fusiform dilatation of the distal CBD (arrow) is demonstrated protruding into the duodenum.

51. Type IV. ) Sagittal view of the liver shows a markedly dilated bile duct (BD) and left hepatic duct (LD). . Transverse view of the left lobe of the liver depicts marked enlargement of the left hepatic duct with dilated branches . Thick-slab MRCP shows both the intrahepatic and extrahepatic involvement.

52. Caroli disease Normally intrahepatic bile ducts develop from primodial cells called ductal plates. Any malformation in this ductal plates leads to congenital diseases of intrahepatic billary tree. So, caroli disease is a rare congenital condition of the intrahepatic billary tree.

53. There are two types of Caroli disease: the simple, classic form and The second, more common form, which occurs with congenital hepatic fibrosis. The second form has also been called Caroli syndrome. Caroli disease has been associated with cystic renal disease, most often renal tubular ectasia (medullary  sponge kidneys). Caroli disease leads to saccular dilation or less often fusiform dilation of the intrahepatic biliary tree, resulting in biliary stasis, stone formation, and bouts of cholangitis and sepsis The disease most often affects the intrahepatic biliary. Cholangiocarcinoma develops in 7% of patients with Caroli disease.

54. Oblique image through the right lobe of the liver demonstrates cystic replacement of the hepatic parenchyma in an extreme case of Caroli disease. Note the incomplete bridging echogenic septa (arrowhead) which produce the “central dot sign.”