MRI - Joints

MRI is short for Magnetic Resonance Imaging. It uses a powerful magnet combined with radio waves to generate detailed images of the inside of the joints.

MRI is painless and does not involve X-rays or any harmful radiation. 

What is MRI scanning of the joints?

Magnetic resonance imaging (MRI) is a non-invasive medical test that physicians use to diagnose and treat medical conditions. 
 
MRI uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of internal body structures. MRI does not use ionizing radiation (x-rays).
 
An MRI examination can be tailored to specific joints, the commonest being the shoulder, hips, knees, ankles and feet but essentially all joints can be assessed. MRI demonstrates the anatomy of joints to a higher degree than other imaging modalities such as x-ray or CT. Detailed MR images of the joints allow physicians to determine the presence of certain conditions.  Common indications include assessing causes of pain such as from an injury or osteoarthritis. MRI is also very good at assessing the soft tissues around the joints which can become inflamed (e.g. tennis elbow). 
 
A more specialised MRI examination of the joints is MR arthrography. This is predominately used in the assessment of the shoulder and hip joints. It is different to routine MRI of the joints in that it requires an injection of MRI contrast dye (gadolinium) into the joint. Typically only specialists such as an Orthopaedic Surgeon would request such a specialised study.

What are some common uses of the examination?

MR imaging of the joints is performed to:

  • Assess for any internal injury to the joint (e.g. anterior cruciate ligament (ACL) tear).
  • Assess the degree of wear and tear in the joint such as cartilage loss or meniscal tear.
  • Assess for any inflammation of the structures around the joint such as the tendons.
  • Assess the reason for a swelling or pain in relation to a joint.
  • On arrival, you will be asked to complete a safety questionnaire. One of our MRI Radiographers will then check your safety questionnaire with you, and explain the examination to you. They will also answer any questions you may have.
     
    You will be asked to change into a gown and to remove any metal, for example jewellery, hairpins, eyeglasses, watches, wigs, dentures, hearing aids and underwire bras. An MRI specialist, the Radiographer, will take you into the scanning room where you will lie on the scanner table. 
     
    Devices that contain coils capable of sending and receiving radio waves may be placed around or adjacent to the area of the body being examined. During an MRI of the head, for example, a device is positioned around the head to improve image quality.
     
    During the MRI you may slowly move through the scanner. The scanner can be quite loud, due to the powerful magnets working within it. You will hear repetitive clicking, tapping and other loud noises. We will ask you, as a precaution, to wear hearing protection and for some scans you may be able to listen to the radio. You will be asked to lie very still so as to ensure clear images are produced . The Radiographer operating the scanner can both see and hear you clearly throughout the scan and will speak to you through an intercom connected to the headphones.
     
    The procedure is painless. You don't feel the magnetic field or radio waves, and there are no moving parts around you. Some patients find it uncomfortable to remain still during the examination.  Others experience a sense of being closed-in (claustrophobia). In this situation, you may want to ask your Physician for a prescription for a mild sedative prior to your scheduled examination. However, fewer than one in 20 patients require this medication.
     
    In some cases, a contrast dye called gadolinium, may be injected through an intravenous line into a vein in your hand or arm. The contrast is not always needed but can enhance the appearance of certain details in the images produced. The contrast used during MRI scans is less likely to cause an allergic reaction than the dye used for CT scans.
     
    If you have not been sedated, no recovery period is required. You may resume your normal activities and diet immediately after the MRI. On very rare occasions, patients experience hives, itchy eyes or other reactions to the contrast dye (if it was used). If you experience symptoms of an allergic reaction, please notify the Radiographer. A Radiologist or other physician will be available for immediate assistance.
     
    MRI Arthrography
     
    If you are having an arthrographic study, you will first undergo a short procedure to inject the contrast dye (gadolinium) into the joint. This is often done under x-ray guidance but may also be performed with ultrasound. This part of the examination only takes a short time (aprox. 10mins). Immediately after the joint is injected, you will be taken on foot to the MRI scanner. The MRI scan of the joint needs to occur within 30 minutes of the injection.