Imaging of the biliary system

DR. RAMURADIOLOGY RESIDENT

CARE HOSPITALS

Biliary Anatomy.

Biliary Ascariasis

• ROUND WORM has a tendency to migrate through natural body orifices and enter Wirsung's duct and common bile duct through papilla of Vater (4). The female parasite is more prone to penetrate through the orifices particularly if the previous sphinterotomy or bilioenteric anastomosis was performed (5, 6). The biliary ascariasis is more common in female. Pregnant women may be more susceptible due to relaxant effect of hormones on the smooth muscle of the bile ducts (7, 8). The presentation of biliary ascariasis is similar to the cholelithiasis, acute cholecystitis, choledocholithiasis, acute pancreatitis and asending cholangitis (9, 10). The round worm may be present both in the CBD and gallbladder in the same patient at a time as in our case.

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Emphysematous cholecystitis.

Common Bile Duct Stone With Mirizzi’s Syndrome:

Biliary tract cancer is the second most common primary hepatobiliary malignancy after hepatocellular carcinoma. Malignancies may occur along any part of the biliary tractfrom the ampulla of Vater to the smallest intrahepatic ductules and the gallbladder. The entire biliary tree, including the gallbladder is lined with a simple columnar epithelium and malignant transformation of this epithelium gives rise to predominantly adenocarcinomas. The pathogenesis of biliary tract and gallbladder carcinoma is thought to be secondary to an evolutionary sequence from metaplasia to dysplasia to carcinoma. Metaplasia usually occurs in the setting of inflammation and chronic injury. Dysplasia of the biliary tract, is considered as pre-invasive biliary neoplasia and can occur in up to 40% to 60% of patients with invasive carcinoma, one third of patients with sclerosing cholangitis, and found incidentally in 1 to 3.5% of cholecystectomy specimens

Classically, the cancers of the biliary tract were separated into three categories: (i) cancer of the intrahepatic biliary tract, (ii) cancer of the gallbladder and extrahepatic bile ducts, and (iii) cancer of the ampulla of Vater. The term cholangiocarcinoma was initially used to refer only to the primary tumors of the intrahepatic bile ducts and is now extended to include intrahepatic, perihilar, and distal extrahepatic tumors of the bile ducts.Gallbladder cancer is defined as cancer arising from the gallbladder and the cystic duct. Ampullary cancers are rare and have better prognosis than cancers of the distal bile duct. Cancers arising from the distal common bile duct immediately adjacent to the ampulla of Vater tend to behave clinically similar to the cancers of the ampulla of Vater, head of pancreas and the duodenal bulb and therefore often considered under the broad category of periampullary carcinomas.

Cholangiocarcinoma: Pathogenesis and Epidemiology

Bile duct cancer arising in the intrahepatic, peri-hilar, or distal biliary tree, exclusive of gallbladder and ampulla of Vater.Originate from epithelial cells of biliary duct90% adenocarcinoma, 10% squamous cell carcinoma.Highly lethal: often locally advanced at presentation.5-year-survival rate: 5-10%.

Risk FactorsPrimary sclerosing cholangitis Life time risk: 10-15%Average age at time of diagnosis: 30s-50sFibropolycystic liver disease i.e. Caroli’s syndrome, congenital hepatic fibrosis, choledochal cystsLifetime risk: 15%Average age at time of diagnosis: 30s-50sParasitic Infection Liver flukes of Clonorchis and Opisthorchis genera (from undercooked fish)Cholelithiasis and haptolithiasisToxic exposure ThorotrastLynch syndrome and biliary papillomatosisChronic liver diseaseViral hepatitis.

Common Clinical Manifestations

Symptoms: Pruritus (66%)RUQ pain (30-50%)Weight loss (30-50%)Fever (20%)Alcoholic stools; dark urineCholangitis(rare

Physical Signs: Jaundice (90%)Hepatomegally (25-40%)RUQ mass (10%)Courvoisier’s sign (rare)

Courvoisier’s sign• states that in the presence of an

enlarged gallbladder which is nontender and accompanied with mild jaundice, the cause is unlikely to be gallstones.

• Usually, the term is used to describe the physical examination finding of the right-upper quadrant of the abdomen.

• This sign implicates possible malignancy of the gall bladder or pancreas and the swelling is unlikely due to gallstones.

CTCourvoisier sign:-

Elevated attenuation (>15HU) of bile within the gallbladder

which is found to be a common and reliable CT indicator of malignant biliary obstruction.

Tumor Classification.

Intrahepatic(Peripheral): small intra hepatic ductules(5-10%)(yellow).Hilar: extrahepatic ductules (including confluence) up to point where common bile duct lies posterior to duodenum(60-70%)Klatskin: involving confluence of left and right hepatic ducts. (blue).Extrahepatic(Distal): originate in extrahepatic biliary duct after CBD travels posterior to duodenum (20-30%).(Orange).

• Hilar cholangiocarcinomas are further sub-classified based on the specific ducts involved Type I

• Type II• Type IIIa• Type IIIb• Type IV

• Type IV is important because it involves both left and right hepatic ducts and therefore is unrespectable.

TNM Tumor StagingStage Grouping:Stage I: T1 N0 M0Stage II: T2 N0 M0Stage IIIA: T3 N0 M0Stage IIIB: T4 N0 M0Stage IIIC: any T N1 M0Stage IV: any T any N T0 No evidence of primary tumorT1 Solitary tumor w/o vascular invasion.T2 Solitary tumor with vascular invasion, or multiple tumors <5cm.T3 Multiple tumors >5cm or tumor involving major branch of portal or hepatic veins.T4 Tumors with direct invasion of adjacent organs other than the gallbladder or with perforation of the visceral peritoneum.

N0 No regional lymph node metastasisN1 Regional lymph node metastasisM0 No distant metastasisM1 Distant metastasis

US of peripheral cholangiocarcinoma.

Cholangiocarcinoma with Hyper-enhancement on Delayed Images

Peripheral cholangiocarcinoma. (a) Arterial-phase CT scan shows a low-attenuation mass (marker) with rim enhancement. Note the dilatation of the peripheral intrahepatic ducts (arrows). (b) On a portal-phase CT scan, the mass looks smaller because the central portion is now more enhanced. The rim enhancement seen in a is partially washed out. Capsular retraction is also noted (arrow).

Peripheral mass-forming cholangiocarcinoma(a) Noncontrast multidetector CT scan obtained prior to contrast material administration shows an irregular hypoattenuating lesion in segments VII and VIII of the liver (arrows) with retraction of the posterior liver surface and atrophy of the right lobe. (b) On an arterial phase multidetector CT scan, the lesion is predominantly hypoattenuating with minimal peripheral enhancement posteriorly (arrow). (c) Delayed phase multidetector CT scan shows the lesion with peripheral enhancement (black arrows) and progressive enhancement posteriorly (white arrow), although the center of the lesion remains hypoattenuating (*).

peripheral cholangiocarcinoma. (a) Fat-saturated T1-weighted MR image obtained after the intravenous administration of gadolinium-based contrast material shows a heterogeneously enhancing lesion (arrows). (b) On a fat-saturated T1-weighted MR image obtained after the administration of manganese dipyridoxylethylenediamine diacetate bisphosphate, the lesion (arrows) appears hypointense relative to the enhancing liver. The use of this contrast agent increases lesion-liver contrast and lesion conspicuity.

Intraductal intrahepatic cholangiocarcinoma in a 53-year-old man. (a) CT scan shows a dilated bile duct in segment VII of the liver (arrows). The bile duct has higher attenuation in the right lobe than in the left lobe. (b) On a T2-weighted MR image, the signal intensity of the right posterior superior intrahepatic duct (B7) (open arrows) is not as high as that of other bile ducts (solid arrows). (c) Photograph of the resected specimen shows granular, friable papillary masses (arrows) in dilated intrahepatic ducts. (Fig 3a and 3c reprinted, with permission, from reference 11.)

MRCP of a classical Klatskin’s tumor. The confluence, proximal hepatic ducts and proximal common hepatic duct are strictured (arrow). The common bile duct is of normal caliber.

Hilar CCA presenting as an intraluminal mass with biliary obstruction. The mass is isodense (arrow) on the coronal non-contrast enhanced CT (a) and hypointense on axial T2-weighted image (b) with upstream dilatation of the intrahepatic ducts. ERCP (c) shows a filling defect (arrow) representing the mass extending into the common bile duct with no filling of the intrahepatic ducts.

Polypoid type iCCA. Axial T2 sections (a, b) and MRCP (c) demonstrating an isointense filling defect (white arrow) in the right hepatic duct and extending into the common hepatic duct with dilation of intrahepatic ducts. Post contrast enhanced T1-weighted images (d-f) shows the mildly enhancing filling defect representing intraductal papillary neoplasm which extended from just under hepatic capsule filling right hepatic ducts to 3 cm below the confluence of right and left hepatic ducts.

Mixed type iCCA. T2-weighted axial (a), MRCP (b), T1-weighted axial (c) and post contrast T1-weighted axial (d) images demonstrating a predominantly periductal thickening (stricturing iCCA) and also mass forming (arrow) in the right lobe liver. Note the separation of the right intrahepatic ducts on MRCP (arrowheads).

Cirrhosis of liver with iCCA. T2-weighted axial (a), T1-weighted axial (b) and post gadolinium enhanced T1-weighted axial arterial phase (c), portal venous phase (d) and delayed phase (e) images showing iCCA as an iso- to hyperintense lesion (arrow) in posterior right lobe with typical arterial phase rim like enhancement and progressive central enhancement through delayed phase without any washout. The liver parenchyma is heterogeneous and nodular consistent with cirrhosis.

Cholangiocarcinoma: Non enhanced, arterial, portal venous and equilibrium phase.

PET-CT of iCCA. Axial PET-CT images showing a large FDG-avid iCCA (arrow) with central photopenia (*) indicating necrosis/fibrosis with FDG-avid portal lymph node (a, arrow head) and aortocaval lymph node (b, arrow head) consistent with lymph node metastases.

Ampullary carcinoma. Contrast enhanced axial CT (a) and coronal reformat (b) showing a small polypoid mass (arrow) representing carcinoma in the ampulla of the bile duct.

Ampullary carcinoma. Contrast enhanced sagittal reformat (b) showing a small polypoid mass representing carcinoma in the ampulla of the bile duct.

B-cell lymphoma of the gallbladder.

Interventions in Obstructive Biliopathy

Percutaneous Transhepatic Cholangiography (PTC)

PTC is a diagnostic procedure which involves placement of a fine needle into a peripheral biliary radicle under image guidance followed by contrast injection to opacify thebiliary tree.

P .T. CThe procedure is used for:

• 1. To define the level of obstruction in patients with obstructive biliopathy.

• 2. To evaluate for presence of suspected choledocholithiasis.

• 3. To determine the etiology of cholangitis.

• 4. To evaluate suspected bile duct inflammatorydisorders.

• 5. To demonstrate site of bile duct leak

• 6.As the preliminary step for draining the biliary tree(most common indication).

Percutaneous Transhepatic BiliaryDrainage(PTBD)

The indicationsinclude:1. To decompress the biliary tree2. To dilate biliary strictures3. To remove bile duct stones4. To divert bile from and stent bile duct defects

• Cholangiogram in a case of carcinoma gallbladder shows complete block of the common hepatic duct just distal to the confluence.

• An external-internal drainage has been instituted with the tip of the catheter in the duodenum

Biliary Stenting

Intraluminal Brachytherapy with PTBD

cases with unresectable tumors causing biliary

obstruction, high dose rate intraluminal brachytherapy(ILBT) using Iridium-192 can be delivered selectively tothe tumor whilst avoiding the side effects of externalradiotherapy. This treatment can be offered in patients• who have a single tumor with an overall stricturof less than 6 cm and

the absence of distant disease. After PTBD, an internal-external drainage is instituted. The brachytherapy catheter is passed through the drainagecatheter and positioned with its tip 1 cm beyond the distal end of the stricturee length

Dilatation of Benign Biliary Structures

Percutaneous Cholecystostomyin a case of empyema of the gallbladder

Complicationsfollowing percutaneouscholecystostomy

• Bile peritonitis,hemobilia and gall bladder perforation.

Vaso-vagal reaction due to tube placement can be managed with atropine.

• Hemorrhage can at times be fatal. Minimal manipulations should be done at the

time of initialdrainage to avoid complications.

AND ,FINALLY

Gallbladder Biopsy

• Percutaneous image guided FNAC biopsy of the gallbladder is a widely used and effective method for the diagnosis of gallbladder masses.

• The accuracy for diagnosing malignancy is more than 90%. It is particularly recommended in patients with inoperable disease for obtaining a histological diagnosis.