Radio Logic Anatomy Of Liver, Biliary Tree By Dr. Talat

RADIOLOGICAL ANATOMY OF LIVER, GALLBLADDER, BILIARY TREE, PANCREAS AND SPLEEN TALAT H.SHARIF MD

Objective  To

identify abdominal structures such as liver, gallbladder, pancreas and spleen on X-Rays, Contrast Studies, CT Scan , Ultrasound and MRI  To be able to understand the relationship of these organ with the structures around them.

Imaging Modalities X-RAYS  ULTRASOUND  CT SCAN  MRI  T-TUBE CHOLANGIOGRAM  MRCP  ORAL CHOLECYSTOGRAM  ENODSCOPIC RETROGRADE CHOLANGIOPANCREATICOGRAPHY (ERCP)  CHOLESCINTEGRAPHY 

Radiographic anatomy on Supine abdominal film  Standard

plain abdominal film is taken with the patient in the supine position.  It may help us to make a specific diagnosis.  It may also provide useful information for determining if any subsequent or more specialized, examinations are needed.

Radiographic anatomy on Supine abdominal film  Plain

abdomen film may also help us  To evaluate the normal soft-tissue densities /organs, and abnormal masses  To find any calcifications in the abdomen if any.

Radiographic anatomy on Supine abdominal film – To evaluate any gaseous lucencies , their distribution and the amount of intraluminal gas, the presence of any abnormal intraluminal collections, and any evidence of extraluminal gas – To evaluate the visualized bones and the lung bases.

Plain Abdominal film(supine) Supine view shows normal liver, kidneys, and psoas muscles. In plain-film estimation of liver size is not very reliable and does not correlate well with clinical estimations of liver size.

Normal soft tissue densities – The normal soft-tissue structures that can usually be identified on plain films of the abdomen include the liver, kidneys, psoas muscles, and bladder . – The normal spleen and the uterus may also be identified. (not always).

– These structures are of water density and are visible because they are largely surrounded by fat.

Normal soft tissue densities 

A supine view of the abdomen shows normal (L), spleen (S), kidneys (K), and psoas muscles ( Psm). The right kidney is lower than left

Liver

Anatomic diagram of abdominal organs

Liver  The

largest organ in the abdominal cavity and the most complex.  Liver occupies most of the right upper quadrant.  upper surface of the liver is almost always adjacent to the inferior surface of the right hemidiaphragm.

Liver  Located

between the fifth intercostal space in the midclavicular line downward and along the right costal margin.  Weighs approximately 1800 grams in men and 1400 grams in women.  Surfaces of the liver are smooth and convex in the superior, anterior and right lateral regions.

Liver 

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Inferior margin of the liver is defined by extraperitoneal fat posteriorly and by gas in the hepatic flexure and transverse colon anteriorly. Right lateral margin of the liver can also be seen because of adjacent fat.

Liver 

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The physical examination defines the anterior margin of the liver. It is the posterior margin of the liver, which is surrounded by retroperitoneal fat, that is consistently visible on radiographs

Liver Liver size is< 13 cm (Normal)  > 15.5 cm is considered hepatomegaly 

Hepatomegaly may be detected by: – Elevation of the right hemidiaphragm anteriorly – Inferior displacement of the hepatic flexure – Left lateral displacement of the stomach.

surfaces of the liver are smooth and convex in the superior, anterior and right lateral regions.

Portal Triad

CT Scan (Porta Hepatis)

Abdominal Ultrasound

RIGHT LOBE LIVER

DIAPHRGAM

COSTOPHRENIC SULCUS

SAGITTAL PLANE

Abdominal Ultrasound

CT Scan of abdomen

Liver  The

liver is divided into two lobes of unequal size and shape. – Right lobe Occupies the right upper quadrant Right hepatic vein divides right lobe into anterior and posterior segments

Liver –Left lobe –Left hepatic vein divides left lobe into medial and lateral segments –Left lobe is much smaller and has a different blood supply and portal drainage from the right lobe

Liver – Caudate lobe

Functionally is part of both right and left lobes because it receives its blood supply from both right and left hepatic arteries – Quadrate lobe Receives its blood supply from the left hepatic artery and is therefore functionally part of the left lobe. Middle hepatic vein divides right from left lobe of liver

Blood supply of the Liver It is important to understand the complex blood flow through the liver  Liver receives blood from two sources– Portal vein – 80% – Hepatic artery – 20%  It drains into the hepatic veins  The hepatic artery, portal vein and bile ducts travel together as portal triad and is covered by connective tissue 

Liver The hepatic artery arises from the celiac axis and courses through the upper portion of the pancreas toward the liver.  The hepatic artery gives rise to the gastroduodenal artery posterior and superior to the duodenum. It divides to right and left hepatic branches and then into smaller branches. In many cases, a third artery supplies portions of segment IV and the right lobe of the liver. 

Liver  The

Couinaud classification accepted internationally and is used in UTZ, CT, MRI. It divides the liver into 8 independent segments each of which has its own vascular inflow, outflow, and biliary drainage  Because of this division into selfcontained units, each can be resected without damaging the remaining

Liver View of the liver showing plane of right hepatic vein as it courses to the IVC.

Liver Shaded-Surface

projection showing how the plane of the right hepatic vein provides the vertical division of the right liver lobe into anterior and posterior segments

Posterior shaded surface view of the liver magnified to show the relation of the caudate lobe with the IVC medially and the fissure for the ligamentum venosum laterally.

CT Scan of Liver 

COUINAD’S Segments Middle hepatic vein

Left hepatic vein

right hepatic vein

Axis of intrahepatic portal vein

Umbilical fissure

• I) Caudate lobe • II) Left posterolateral segment • III) Left anterolateral segment • IVa) Left superomedial segment • IVb) Left inferomedial segment • V) Right anteroinferior segment • VI) Right posteroinferior segment • VII) Right postero-superior segment • VIII) Right anterosuperior segment

Shaded surface view showing that the course of the middle hepatic vein falls roughly along a plane extending from the gallbladder fossa and the IVC. This plane divides the right hepatic lobe from the left hepatic lobe

MIP and shaded-surface views showing that the plane of the umbilical fissure divides the left lobe into medial and lateral portions which need to be further divided to qualify as independent Couinaud segments.

Left hepatic lobe: MIP and shaded-surface views showing that the plane of the left hepatic vein subdivides the lateral portion of the left hepatic lobe

MIP and shaded surface views showing the plane of the main intrahepatic portal vein Note this plane (arrow on surface view) is roughly horizontal but in some cases may be angled The dotted line indicates how this plane is sometimes used to divide segment IV into superior (IVa) and inferior (IVb) divisions.

Ultrasonographic view of the portal vein

branches to the Couinaud segments 5, 6, 7, and 8

Ultrasonographic view of the portal vessels locating the central portions of the Couinaud segments of the left liver lobe

Ultrasonographic view of the confluence of the right (rhv), middle (mhv), and left (lhv) hepatic veins with the IVC

Doppler Study of Liver

CT Scan of the Liver

Gall Bladder & Biliary Tree

Gallbladder Small pear-shaped sac  Sits in between the right and quadrate lobes of the liver  30-50 cc in capacity  Connected to the liver by connective tissue  Parts of the gall bladder: – Fundus – Body – Neck 

LIVER

RIGHT AND LEFT HEPATIC DUCTS COMMON HEPATIC DUCT

CYSTIC DUCT PANCREATIC DUCTS

GALLBLADDER

AMPULLA OF VATER

COMMON BILE DUCT DUODENUM

Biliary Drainage System  Hepatic

ducts  Cystic duct  Pancreatic duct  Common bile duct  Ampulla of Vater

Gallbladder  Relationship

to other structures:

–Anterior Anterior abdominal wall –Posterior Transverse colon Duodenum –Superior Under surface of liver

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Ultrasound of GB and Biliary tree – –

Painless, non-invasive procedure. does not require special preparation, although it is technically easier in patients with at least six hours of fasting. – Usually recommended as the first imaging modality for the investigation of patients with suspected cholangiocarcinoma. – In hilar cholangiocarcinoma, ultrasound demonstrates bilateral dilation of intrahepatic ducts, and right and left hepatic ducts

Ultrasound of GB and Biliary tree The best noninvasive test for detecting gallstones in the gallbladder is abdominal ultrasonography because of its high specificity and sensitivity (90–95%)  Does not employ ionizing radiation, and provides accurate anatomical information.  May also indicate distal obstruction by the finding of dilated intrahepatic or extrahepatic bile ducts.  Less useful for excluding gallstones obstructing the common bile duct. 

Ultrasound of GB and Biliary tree

GALLBLADDER ON ULTRASOUND Common Bile Duct If transverse diameter of gallbladder is more than 5 cm with round configuration instead of ovoid it means that it is hydropic

Portal Vein

Gall Bladder

Transverse diameter less than 2 cm inspite of adequate fasting means it is abnormally contracted

Ultrasound of Gallbladder and Biliary tree

Acute cholecystitis

Acute cholecystitis

Computed Tomography (CT) of GB and Biliary Tree May detect lesions like low-density mass or stone in GB or in dilated biliary ducts .  Produces different pictures depending on location of the tumor and the level and degree of obstruction.  Clearly show hilar masses causing bilateral dilation of intrahepatic biliary ducts.  May detect tumors causing dilatation of intra- and extrahepatic bile ducts and gallbladder. 

Computed Tomography (CT) of GB and Biliary Tree Useful in demonstrating masses and dilated biliary ducts, although they are not as reliable for the diagnosis of calculous disease.  Principal use is detection of the complications of gallstones such as pericholecystic fluid, gas in the gallbladder wall, gallbladder perforations, and abscesses.  May help determine which patients will require urgent surgical intervention . 

Computed Tomography (CT) of Gallbladder

Computed Tomography (CT) of Gallbladder and Biliary Tree

Magnetic Resonance Imaging (MRI)  

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Slightly superior to computed tomography in visualization of body structures and tumors. Allows visualization of both dilated biliary ducts proximal to the tumor and normal-sized extrahepatic ducts distal to the level of occlusion. Images obtained from the newest diagnostic equipment are comparable in quality to those obtained with Endoscopic Retrograde Cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiography. Ductal or intravenous injection of contrast medium is not necessary and the patient is not exposed to irradiation.

MRI Abdomen

Endoscopic Retrograde Cholangiopancreatography (ERCP) Endoscopic Ultrasound (EUS)  

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The patient is placed in the supine or tilted towards left. During this procedure, pharyngeal topical anesthetic agent are administered to prevent gagging. Pain medication and a sedative may also be given prior to the procedure. Allows physician to visualize and biopsy the mucosa of the upper gastrointestinal tract. Endoscopy permits visualization of the esophagus, stomach and duodenum. Enteroscope allows visualization of at least 50% of the small intestine, including most of the jejunum and part of the ileum.

Endoscopic Retrograde Cholangiopancreatography (ERCP)

ERCP

Endoscopic Retrograde Cholangiopancreatography (ERCP) Endoscopic procedure involves the use of fiberoptic endoscopes .  The side-viewing endoscope is introduced into the second portion of duodenum, and contrast material is injected into the bile ducts via major duodenal papilla under fluoroscopic guidance .  Multiple x-ray pictures are taken to visualize the distribution of the contrast in the biliary tree. ERCP can demonstrate normal size & structure of the extrahepatic ducts distal to occlusion and dilated intrahepatic ducts proximal to occlusion . 

ERCP

Percutaneous Transhepatic Cholangiography

Percutaneous Transhepatic Cholangiography  Another

invasive procedure performed by a radiologist under fluoroscopic guidance. A small needle is introduced through the liver into one of the peripheral biliary ducts. Contrast material is injected through the needle and x-ray pictures obtained to document the biliary tree anatomy.

Percutaneous Transhepatic Cholangiography 

For tumors of the middle third of extrahepatic duct, surgical options include resection of the mass with possible primary end-to-end bile duct anastomosis (for early small tumors) or hepatojejunostomy (if large portion of extrahepatic ducts should be removed). For tumors located in distal common bile duct, as inWhipple procedure

MRI and MRCP These are relatively new applications that utilizes MRI imaging with special software.  Capable of producing images similar to ERCP without the accompanying risks of sedation, pancreatitis, or perforation.  Helpful in assessing biliary obstruction and pancreatic ductal anatomy.  Effective in detecting gallstones and to evaluate the gallbladder for the presence of cholecystitis.  Major shortcoming of MRCP lies in the experience of the interpreting physician. 

Oral Cholecystography  

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Considered cheap and noninvasive test. Patient must ingest a dose of an oral contrast agent on the evening before the test. This contrast is absorbed and secreted into the bile. The iodine in the contrast produces opacification of the gallbladder lumen on a plain radiograph the next day. Gallstones appear as filling defects. Main use of oral cholecystography is to establish patency of the cystic duct. This information is required before attempting lithotripsy or medical methods to dissolve gallstones. A major drawback of oral cholecystography is that it takes 48 hours to perform, which limits its usefulness in patients with acute cholecystitis and gallstone complications and increase risk of toxicity by the contrast- not popular.

Cholescintigraphy 

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Employs the use of an intravenous radioactive iminodiacetic acid derivative which is rapidly absorbed by the liver and excreted into the bile. Serial scans demonstrate the radioactivity in the gallbladder, common bile duct, and small bowel within 30–60 minutes. A nonfunctioning gallbladder is diagnostic of acute cholecystitis. May be useful in determining whether cholecystectomy will benefit a patient with chronic biliary pain without gallstones.

RIGHT AND LEFT HEPATIC DUCTS

CYSTIC DUCT

Cholangiogram COMMON HEPATIC DUCT

COMMON BILE DUCT

CT Scan with Contrast

Pancreas

Pancreas  Total

length – 12.5 to 15.0 cm  Head measures approx. 1.5- 2.0 cm  Neck measures approx. 1.0 cm  Body measures approx. 2.0 cm  Tail measures approx. 2.0-3.0 cm  Normal pancreatic duct 2 mm  The head & body are retroperitoneal structures while tail is intraperitoneal

Pancreas The pancreas is 12-15 cm long and is located in the epigastrium  Has four parts: – Head Uncinate process – Neck – Body and tail  The head and body lie outside peritoneum  The head of the pancreas is surrounded by the duodenum as it makes a C-loop around the pancreas 

Imaging of Pancreas- CT scan

Acute pancreatitis

Ultrasound of Pancreas

Pancreas 

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The pancreas lies behind the peritoneum of the posterior abdominal wall and is oblique in its orientation. The head of the pancreas is on the right side and lies within the “C” curve of the duodenum at the second vertebral level (L2). The tip of the pancreas extends across the abdominal cavity almost to the spleen. Collecting ducts empty digestive juices into the pancreatic duct, which runs from the head to the tail of the organ.

Pancreas  The

pancreatic duct empties into the duodenum at the duodenal papilla, alongside the common bile duct.  Smooth circular muscle surrounding the end of the common bile duct (biliary sphincter) and main pancreatic duct (pancreatic sphincter) fuses at the level of the ampulla of Vater is called the sphincter of Oddi.

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The distal end of the common bile duct can be found behind the upper border of the head of the pancreas. This duct courses the posterior aspect of the pancreatic head before passing through the head to reach the ampulla of Vater (major papilla).

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The pancreas may be divided into five major regions—the head, neck, body, tail and uncinate process. The uncinate process is the segment of pancreatic tissue that extends from the posterior of the head. The neck of the pancreas, a part of the gland 3–4 cm wide, joins the head and body. The pancreatic body lies anteriorly in contact with the antrum of the stomach.

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The Duct of Wirsung is the main pancreatic duct extending from the tail of the organ to the major duodenal papilla or Ampulla of Vater . The widest part of the duct is in the head of the pancreas (4 mm), tapering to 2 mm at the tail in adults. The duct of Wirsung is close, and almost parallel, to the distal common bile duct before combining to form a common duct channel prior to approaching the duodenum. In approximately 70% of people, an accessory pancreatic duct of Santorini (dorsal pancreatic duct) is present. This duct may communicate with the main pancreatic duct. The degree of communication of the dorsal and ventral duct varies from patient to patient.

Pancreas  The

common bile duct traverses through the head of the pancreas and joins with the pancreatic duct at the ampulla of Vater to empty bile into the second or descending part of the duodenum  Both the pancreatic ducts of Santorini and Wirsung drain the exocrine pancreas

Relationship of Pancreas – Head Posterior –SMV –Splenic vein –IVC –Terminal portion of renal vein –Right crus of diaphragm Anterior –Transverse colon –Uncinate process passes in front of aorta

Relationship to Surrounding Structures Lateral

Bile duct –Bile – Neck Anterior Pylorus –Pylorus Omental bursa –Omental Posterior SMV –SMV Beginning of portal vein –Beginning

Relationship to Surrounding Structures – Body  Anterior – Stomach separated by omental bursa  Posterior – Aorta – SMA – Left crus of diaphragm – Left adrenal – Left kidney – Left renal vein – Splenic vein

Relationship to Surrounding Structures Inferior

Transverse mesocolon –Transverse Duodeno-jejunal junction –Duodeno-jejunal Left colic flexure –Left Superior border Splenic artery –Splenic – Tail The tail of the pancreas lies in the splenorenal ligament and enters the hilum of the spleen with splenic vessels.

Ultrasound of Pancreas

Ultrasound of Pancreas

CT Scan of Pancreas

Spleen

Spleen on Plain X-ray  Recognizable

as a soft-tissue density measuring 8 cm to 12 cm in length, high under the left hemidiaphragm and lateral to the stomach.

Spleen  Size

may vary considerably(< 15 cm in adult & 50% decrease in old age).  When enlarged, the spleen frequently displaces the gas-filled splenic flexure of the colon in an inferomedial direction and may also displace the stomach medially.  Significant splenomegaly may be diagnosed quite accurately on plain abdominal films.

Ultrasound of Spleen

CT Scan of Spleen

Adrenal Glands

Adrenal Glands  Anatomically,

the adrenal glands are located in the abdomen, situated on the anterosuperior aspect of the kidneys  They are found at the level of the 12th thoracic vertebra

Adrenal Glands  Arterial

supply –

– Superior suprarenal artery – Middle suprarenal artery – Inferior suprarenal artery  Venous

supply

– Suprarenal veins only – Among all imaging modalities CT is considered the first line of investigations, UTZ preferred in children

Adrenal Glands  Normal

adrenal in adults weighs about 3 to 6 grams each. Average size is 3 to 5 cm (L) X 2 to 3 cm (W)  Right is triangular in shape lying adjacent to the upper pole of kideny behind IVC.  Left is semilunar in shape and lies anteromedial to the upper pole of left kidney.

Imaging of Adrenal Glands

The adrenal glands are located in the perirenal space near the upper pole of each kidney

Normal left adrenal gland Right adrenal mass

 Late

phase of contrast enhanced Ct shows a right adrenal mass with central area of necrosis

Normal right adrenal gland

Contrast-enhanced axial CT scan showing a right adrenal mass enlarging the gland and giving it a bulbous appearance

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