In this presentation, we will be reviewing the anatomy of the liver and biliary system,
as well as a brief overview of the radiological procedures you may encounter with each.
The liver is largest gland in the body.
The falciform ligament divides liver into two major lobes, the right lobe and the left
lobe.
Two minor lobes are present on visceral surface, the Caudate lobe and the Quadrate lobe.
The liver is supplied by Two blood supplies: Hepatic artery supplies oxygenated blood from
abdominal aorta AND Portal vein carries blood from digestive system to be filtered by liver.
The primary function of the liver from an imaging standpoint is the production of bile,
which is collected by ducts and carried to the gallbladder for storage – or it can
pass into the duodenum.
Here we see the biliary system, which is composed of the gallbladder and bile ducts, and how
it connects with the duodenum.
There are two main ducts in the liver – the right hepatic duct and the left hepatic duct.
These join to form the common hepatic duct, which unites with the cystic duct to form
the common bile duct.
The gallbladder itself is a thin-walled musculomembranous sac usually found on the visceral surface
of the right lobe of the liver, but its position may vary with body habitus.
It functions to store and concentrate bile, and evacuates bile when activated by the hormone,
cholecystokinin.
Here we see there is a fundus, a body, and a neck portion of the gallbladder.
The neck is consistent with the cystic duct.
We don’t typically perform oral cholecystograms anymore with the advances in CT technology,
but the image on the left shows the gallbladder highlighted with contrast called bilopaque.
Sonography of the gallbladder is still very common.
As you can see, the location of the gallbladder can shift extensively as body habitus changes.
In general, the larger the patient size, the more superior and lateral the gallbladder
will be.
The smaller the patient size, the more inferior and central it is.
More common procedures still seen today by radiologic technologists include percutaneous
transhepatic cholangiography, Postoperative (T-tube) cholangiography, and ERCPs, or endoscopic
retrograde cholangiopancreatography.
Percutaneous Transhepatic Cholangiography: Abbreviated PTC, these are performed on patients
with jaundice when the ductal system has been demonstrated as dilated by computed tomography
(CT) or sonography, but the cause is unclear.
It may also be used to place a drainage catheter to treat obstructive jaundice.
For these procedures, the patient lies supine while their right side is surgically prepared
and draped.
Local anesthetic is administered and a special “skinny” needle is inserted.
Water-soluble iodinated contrast is injected under fluoroscopy, filling the ductal system,
and spot AP projections are recorded.
T-Tube Cholangiograms are performed post-op and are sometimes called delayed cholangiograms.
These are when a T-shaped tube that is left in the common hepatic and common bile ducts
for post-operative drainage are injected with contrast media.
They are performed to demonstrate patency of the ducts, status of the sphincter of the
hepatopancreatic ampulla, and in the presence of residual or previously undetected stones.
The tube gets clamped the day before the procedure, which fills the tube with bile to prevent
air bubbles from entering (air bubbles can mimic radiolucent stones).
The preceding meal is withheld and a cleansing enema 1 hour before the procedure is administered
if needed.
Usually a scout KUB is obtained.
During the procedure, the patient is placed in the RPO position with their right upper
quadrant centered to the IR.
Contrast media is injected into the T-tube under fluoroscopy, then spot and conventional
(overhead) images are taken as indicated by the radiologist.
ERCPs are used to diagnose biliary and pancreatic pathologic conditions with a fiber-optic endoscope
through the mouth into the duodenum under fluoroscopy.
This method is useful when ducts are not dilated and the ampulla (where the common bile duct
empties into the duodenum) is not obstructed.
The patient’s throat is sprayed with a local anesthetic to make passage of the endoscope
easier.
The hepantopancreatic ampulla is cannulated with video guidance.
There’s a camera on the end of the scope that the physician views to help with visualization.
Once the cannula has successfully been inserted into the ampulla, contrast is injected into
the common bile duct, then spot and/or conventional images are taken as needed.
It’s not uncommon for the technologist to assist with fluoroscopic guidance for these
procedures in the operating room with the patient under full sedation, but these can
be performed under conscious sedation as well.
It is important for the technologist to ensure the contrast is followed with the fluoroscope
to include the major ducts.