Orthopedic MR Imaging: New Levels of Diagnostic Information on Sports Injuries

The New Magnetom Jazz is a patient-friendly orthopedic MR system from Siemens Medical Solutions
(MR patient positioning: shoulder, wrist, ankle and image montage: shoulder, ankle, elbow)

Magnetic Resonance (MR) imaging can non-invasively diagnose a number of sports related injuries without requiring surgery or arthroscopy. X-ray images of joints show good detail of bony structures and can clearly show a fracture. However, x-ray images give insufficient information about the soft tissue structures that hold joints together and allow the joint to support complex function. MR can yield detailed images and information on a number of bone and joint tissues like cartilage, tendon, ligament, bone marrow, bone cortex, muscle and joint fluids. With the development of new MR systems and techniques over the past five to ten years, MR has become an indispensable tool in diagnosing sports related injuries. MR imaging provides an optimal means to acquire high contrast images of both the bone structures and the soft tissue structures which together create a complex joint such as the knee or shoulder. More and more, MR imaging is being used as the main diagnostic tool in sports medicine while arthroscopy is being used as the guiding light for minimally invasive joint surgery.

New dedicated orthopedic MR systems

Whole-body magnetic resonance imaging systems allow imaging of nearly every organ and structure in the human body. Whole body MR systems can image the brain, spine, liver, joints, extremities (limbs), blood vessels, heart and other organs in the body. However, these whole body systems are very expensive to own and operate because of their size and cost to manufacture. In the past few years, several medical systems manufacturers have developed new orthopedic MR systems that are primarily dedicated to imaging joints. This latest generation of extremity MR systems are very compact and combine orthopedic imaging performance with claustrophobia-free comfort for patients in a system that is far less expensive to own and operate. Further, these systems are small enough to be sited almost anywhere, even in the outpatient offices of orthopedic practices. Over the next several years these dedicated extremity systems will allow MR imaging to be conveniently accessible to more patients with orthopedic problems and sports related injuries. The image strip at the top of the page shows one of the newest orthopedic MR systems available.

Orthopedic Imaging with MR: Orientation Flexibility and Tissue Detail

MR has incredible flexibility in its ability to selectively image and highlight specific tissues like the knee's meniscus or anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL). MR has the unique ability to directly acquire images in almost any orientation so that surgeons can get a perfectly aligned view of a torn ACL. New three-dimensional MR (3D MR) techniques allow doctors to acquire an entire volume of data (for instance the entire knee). The doctors can then use the computer to go back and reconstruct images with the exact view or orientation that they need to see the pathology. "Musculoskeletal Imaging" is a specialized subset of MR imaging that is specifically geared towards imaging joints.

MR image of the knee showing posterior cruciate ligament (arrow)

Musculoskeletal (or orthopedic) MR imaging is still a specialized field of MR and requires extensive experience and skill by the radiologist and technologist performing the MR exam. High quality musculoskeletal MR diagnosis also requires state-of-the-art MR systems, MR acquisition sequences and special so called "surface coils" which allow more detailed images of shoulder, knees, wrists and other complex joints. Even detailed MR images of the small joints and tendons in the finger can now be acquired.

High resolution MR image of the finger

MR imaging is now used to diagnose various joint injuries and conditions:

• arthritis: inflammation of the joint or lining of the joint
• bursitis: inflammation of the bursa, the membrane surrounding a joint. A common form of bursitis is sub-deltoid (shoulder) bursitis which if left untreated can lead to "frozen shoulder"
• chondromalacia patellae, a painful disorder of the knee in which the cartilage behind the kneecap is damaged or worn down resulting in inflammation
• contusions (bruise) of the bone
• edema or swelling of the bone marrow in athletes or people who have multiple impact or repetitive stress in their bones and joints from such sports as basketball
• ligament tears: injury to the anterior cruciate ligament (ACL) is extremely common
• meniscal tears of the knee, elbow and TMJ, the meniscus (a crescent-shaped disk of cartilage) is held in place by joint ligaments and reduces friction during joint movement
• orthopedic imaging of the spine: MR can show early degeneration in discs before herniation and can also image nerve roots which are inflamed or compressed.
• stress fracture: small hair line cracks in the bone can be detected early with MR
• tendinitis: inflammation of the tendons, for example the Achilles tendon

Updated: November 2, 2007