Magnetic resonance cholangiopancreatography (MRCP)

What is an MRCP test?

Cholangiopancreatography (CP) is a type of imaging technology that allows doctors to examine the pancreatic duct and common bile duct (into which the liver and gallbladder drain) using images instead of surgery. The scan helps doctors determine whether the ducts are blocked, narrowed or dilated.

There are three types of CP:

• Magnetic resonance cholangiopancreatography (MRCP)
• Endoscopic retrograde cholangiopancreatography (ERCP)
• Percutaneous transhepatic cholangiography (PTC)

MRCP is a noninvasive CP scan, meaning doctors don’t need to place anything inside the patient to gather the images.

How does MRCP work?

MRCP is a type of magnetic resonance imaging (MRI) scan. MRIs use strong magnets and radio waves to produce images of thin layers of tissue until the full target area is captured—for MRCP, that area is the bile and pancreatic ducts.

A computer then groups the images together to show the whole duct system from different angles. Though not required, doctors may inject a dye (also called a contrast agent) to help improve the imaging results.

How do ERCP and PTC work?

The other two forms of CP are ERCP and PTC. Unlike MRCP, ERCP and PTC are considered invasive procedures.

Endoscopic retrograde cholangiopancreatography (ERCP)

ERCP uses X-rays to gather images of the bile and pancreatic ducts. The doctor views the ducts using an endoscope (a flexible tube with a light and video camera at the end), inserting the device through the mouth and down to the duodenum, where the ducts empty into the small intestine.

The doctor then passes a catheter (a thin tube) through the endoscope to inject dye into the ducts so they’ll show up in X-rays. The doctor may also remove small tissue or fluid samples (biopsies) or, if needed, place a stent to keep a section of a duct open.

Because this procedure is invasive, doctors generally sedate patients (giving them medicine to help them relax or make them sleepy) before an ERCP.

Percutaneous transhepatic cholangiography (PTC)

PTC also uses X-rays to view the bile and pancreatic ducts. It’s more invasive than ERCP and comes with more discomfort and risk. Doctors mainly use PTC if they’ve already tried or can’t perform an ERCP.

Before the PTC, the doctor will numb the abdomen and give the patient a sedative or general anesthesia to render him or her unconscious. Next, guided by X-rays or ultrasound, the doctor inserts a needle through the skin and into the liver to inject dye into the bile ducts. The doctor then takes X-rays of the ducts while the dye passes through them. The doctor may also take biopsies, drain excess bile and place a stent during the procedure.

MRCP vs. ERCP

MRCP differs from ERCP and PTC in several ways:

• MRCP is noninvasive. ERCP and PTC are invasive.
• Because MRCP is noninvasive, there’s no way to collect biopsies or place stents, which may be performed during ERCP or PTC.
• MRCP uses radio waves and a strong magnetic field to gather images. ERCP and PTC use X-rays, which is a type of radiation.
• MRCP doesn’t require numbing, sedatives or anesthesia, unlike ERCP and PTC.
• MRCP comes with minimal risk, while ERCP or PTC may cause perforating (a hole in) the ducts or intestine, pancreatitis and possible sedation-related side effects.

What is the purpose of MRCP?

Doctors use MRCP scans as noninvasive alternatives to ERCP scans. These scans provide information on diseases and conditions affecting the liver, gallbladder, bile ducts, pancreatic ducts and pancreas—including bile duct cancer (cholangiocarcinoma) and pancreatic cancer, infection, inflammation (pain, heat, redness, swelling and loss of function), and gallstones and bile duct stones.

For example, if someone has pancreatitis (inflammation of the pancreas), an MRCP scan may help show the pancreas’ healthy tissue, scarring and functionality. A doctor may also perform an MRCP scan to try to determine the source of abdominal pain.

MRCP preparation

A care team may provide information on how to prepare for an MRCP before the appointment. Generally, patients:

• Can’t eat and drink for several hours before the procedure
• Provide information about their allergies, as the dye (gadolinium) may cause reactions in some patients
• Provide information about their health history, health conditions and medications
• Should let the care team know if they’re pregnant, as pregnant people should avoid gadolinium
• Should let the care team know if they’re claustrophobic (have a fear of confined spaces), since these patients may benefit from a sedative during the procedure
• Leave jewelry, watches, body piercing art, hairpins, removable dental devices, pens, glasses, cell phones or similar items outside the scanning area
• Should let the care team know if they have metal in their bodies (like shrapnel or bullets) or implanted medical devices—such as stents, cardiac defibrillators, pacemakers, vagal nerve stimulators and some cochlear (hearing) implants—since MRI scans use magnets

People who have metal in their bodies should stay away from the MRI scanning area until the care team determines it’s safe. Objects containing metal or electronics may interfere with the scan and cause burns, or they may move during the procedure. Additionally, an MRI may cause blindness if there are metal fragments, like shrapnel or bullets, near or in the eyes. In rare instances, some tattoo dyes contain iron that may get hot during the procedure.

What happens during an MRCP procedure?

If given dye for an MRCP scan, the patient will receive the substance through an intravenous (IV) line (a soft tube placed in a vein) or orally (by mouth). IV lines may cause some discomfort and a small bruise. The oral dye may have an unpleasant taste and make the stomach feel full.

The patient will lie on a narrow table that slides into the MRI scanner, and the technician will go to an adjoining control room and communicate with the patient via an intercom. During the scan, the technician will take several series of images with breaks in between each series. The patient will need to stay still and in the proper position while the technician takes the images.

While it takes images, the machine will make repetitive banging and thumping sounds. This happens when the coils that generate the radio waves activate. The patient may be able to listen to music or wear headphones to help block out the noise during the scan.

MRCP scans last about 15 minutes. If paired with abdominal scans, they may take another 30 minutes. Afterward, patients may leave and resume their usual diet and activities. Those who were sedated will need a ride home.

A few people experience allergic reactions to the dye, such as a rash or itchy eyes. If this happens, patients should let their care team know immediately.

What are the benefits of an MRCP?

MRCP is designed to have these benefits:

• It’s noninvasive.
• It doesn’t use ionizing radiation.
• It provides detailed images of soft tissue, including areas that may be blocked by bones when using other imaging techniques.
• It uses gadolinium, a contrast dye that is less likely to cause allergic reactions than the iodine-based dye used for X-rays.

What are the risks of an MRCP?

MRCP risks include:

• Possible allergic reactions to the dye: Most allergic reactions are mild. However, people with serious kidney disease could have a rare reaction to gadolinium, called nephrogenic systemic fibrosis.
• Too much sedative: During the scan, the MRI team will monitor the patient’s vital signs to safeguard against this risk.
• Disruptions to medical implants: The powerful magnetic field of the MRI machine may cause implanted medical devices to malfunction.
• Claustrophobia: People with severe claustrophobia may require medicine to relax.

What are the limitations of an MRCP?

MRCP limitations include:

• Requiring patients to stay still for the scan to get clear images
• Avoiding interference from metallic implants or objects
• Difficulty getting clear images for patients with seriously irregular heartbeats: Some MRCPs use the heart’s electrical activity to time the procedure, so a seriously irregular heartbeat may prevent them from getting clear images.
• Needing to avoid gadolinium while pregnant: Although MRI hasn’t been shown to harm a fetus, doctors may delay the procedure until after delivery.