An MRCP scan is a scan that uses magnetic resonance imaging (MRI) to produce pictures of the liver, bile ducts, gallbladder and pancreas.
Note: the information below is a general guide only. The arrangements,and the way tests are performed, may vary between different hospitals. Always follow the instructions given by your doctor or local hospital.
What is MRCP?
MRCP stands for magnetic resonance cholangiopancreatography. MRCP is a type of magnetic resonance imaging (for more information see the separate leaflet called MRI Scan). MRCP produces detailed images of the liver, gallbladder, bile ducts, pancreas and pancreatic duct.
What is MRCP used for?
The uses of MRCP include:
- Checking the liver, bile ducts, gallbladder and pancreas for gallstones, tumours, infection or inflammation.
- Investigating the cause of inflammation of the pancreas (pancreatitis).
- Investigating unexplained tummy (abdominal pain).
- Used as a less invasive alternative to endoscopic retrograde cholangiopancreatography (ERCP). See separate leaflet called ERCP for more information.
The bile ducts and nearby structures
Bile is made in the liver. The liver is in the upper right part of the tummy (abdomen). Bile passes from liver cells into tiny tubes called bile ducts. These join together (like the branches of a tree) to form the common bile duct. Bile constantly drips down the common bile duct, and through an opening called the papilla into the the first part of the gut after the stomach (the duodenum).
The gallbladder lies under the liver on the right side of the upper abdomen. It is like a pouch which comes off the common bile duct. It is a 'reservoir' which stores bile between meals. The gallbladder squeezes (contracts) when you eat. This empties the stored bile back into the common bile duct. The bile passes along the remainder of the common bile duct into the duodenum. Bile helps to digest food, particularly fatty foods.
The pancreas is a large gland that makes enzymes (chemicals). These flow down the pancreatic ducts, into the main pancreatic duct, and through the papilla into the duodenum. The pancreatic enzymes are vital to digest food. (The pancreas also makes some chemicals (hormones) such as insulin.)
How does MRCP work?
MRCP uses MRI technology. It is essentially an MRI scan, which uses a strong magnetic field and radio waves to create pictures of tissues, organs and other structures inside your body, on a computer. Sometimes you may receive an injection of 'contrast' when you have this test. Contrast is a substance that enhances the MRI picture. It makes it easier for doctors to see the different parts of the body.
How does an MRI scan work?
Your body contains millions of hydrogen atoms. When you are in an MRI scanner:
- A strong magnetic field aligns particles called protons which are within the hydrogen atoms. All the protons line up in parallel with the magnetic field, like tiny magnets. (Normally the millions of protons all lie in random directions.)
- Then, short bursts of radio waves are sent from the scanner into your body. The radio waves knock the protons from their position.
- When the burst of radio waves stops, the protons realign back into place. As they do so they emit radio signals. The protons in different tissues of the body realign at different speeds. Therefore, the signal emitted from different body tissues varies. So, for example, softer tissues can be distinguished from harder tissues on the basis of the signals sent.
- These signals are detected by a receiving device in the scanner.
- The receiving device transmits the signals to a computer. The computer creates a picture based on the radio signals emitted from the body.
What happens during an MRCP?
An MRCP is carried out in an MRI scanner. The MRI scanner is like a tunnel about 1.5 metres long surrounded by a large circular magnet. You lie on a couch which then slides into the scanner. A 'receiving device', like an aerial, is placed behind, or around, the part of the body being examined. This detects the tiny radio signals emitted from your body. When each 'picture' is being taken you need to keep still for a few minutes, otherwise the scan picture may be blurred.
The scan itself is painless. The whole procedure can take 15-40 minutes. It may be a little uncomfortable lying still on the couch for this time. In some cases an injection of a special contrast dye is given into the bloodstream via a vein on the arm.
The radiographer sits in the control room next to the scanner and observes through the window. However, you can talk to them, usually via an intercom and you will be observed at all times on a monitor.
The scanner is noisy so you will be given some headphones or earplugs to protect your ears from the noise. Quite often you can listen to the radio through the headphones or bring a CD to listen to.
What should I do to prepare for an MRCP?
Usually very little. Your local hospital should give you information about what is required before you come for the scan. Because an MRCP involves the use of an MRI scanner there are certain safety procedures involved. The MRI scanner uses an extremely strong magnet, so people with certain types of medical implant cannot be scanned. This is because the magnet can potentially move medical devices with metal in them, or affect their function.
Before you enter the scanning area you should be asked if you have any medical devices in your body.The following is not a definitive list but may help remind you of the type of things radiographers need to know about.
You should tell the radiographer if you have any of the following:
- Internal (implanted) defibrillator or pacemaker
- Cochlear (ear) implant
- Surgical clips such as those used on brain aneurysms
- Artificial heart valves
- Implanted medicine infusion ports
- Implanted electronic device, including a cardiac pacemaker
- Artificial limbs or metallic joints
- Implanted nerve stimulators
- Pins, screws, plates, stents or surgical staples
It is also important to tell the test operator if you have ever had any metal fragments lodged in your eyes or your body. In some cases you may need an X-ray before the scan to make sure you are safe to enter the scanner.
What can I expect after an MRCP?
There are no after-effects from the scan. You can return to your normal activities as soon as the scan is over.
The pictures from the scan are studied by an X-ray doctor (a radiologist) who sends a report to the doctor who requested the scan.
Are there any side-effects or complications from an MRCP?
MRCP scans use MRI which is painless and safe. Unlike X-rays and some other imaging tests, an MRI scan does not use radiation. However:
- Rarely, some people have reactions to the contrast dye which is sometimes used.
- Pregnant women are usually advised not to have an MRI scan unless it is urgent. Although the scan is thought to be safe, the long-term effects of strong magnetic fields on a developing baby are not yet known.
Dr Rachel Hoad-Robson
Dr Laurence Knott
Dr Adrian Bonsall