Since its introduction in the 1980s, Magnetic Resonance Imaging (MRI) has become a staple in the assessment of sports injuries. MRI has significant advantages over plain x-rays and CT scans. MRI enables physicians to see very subtle abnormalities in the soft tissues of the body, including ligaments, tendons, and cartilage. X-ray based imaging is less sensitive toward injuries of these structures, and therefore has a limited role in evaluation of soft tissue injuries. Common knee injuries such as ligament cartilage and tendon tears, as well as muscle strains and tears, are well demonstrated on MRI scans.
What is an MRI scan?
MRI is a diagnostic test in which pictures are taken of the structures inside the body. MRI, unlike CT scans, does not use radiation or X-rays to generate the pictures. Instead, MRI scanners use a magnetic field, and different radio waves to create images. MRI scans are very sensitive to the composition of soft tissues, such as fat, muscle, bone and cartilage, allowing a detailed assessment of most joints.
Injuries Diagnosed by MRI
- Ligament tears
- Cartilage tears
- Fractures
- Bone bruises
- Muscle strains or tears
Ligament Tears on MRI
There are four knee ligaments – the anterior and posterior cruciate ligaments, and the medial and lateral collateral ligaments. Tears of these structures are readily diagnosed on MRI scans. The knee ligaments have a distinctive dark or “low signal” appearance on MRI scans when normal. Torn ligaments show a disruption of normal fibers along with abnormal fluid in the ligament.
Cartilage Tears
Cartilage tears fall into two different categories – mensical tears, which involve the cushioning cartilage disks in the knee, and hyaline catilage tears, which affect the lining of the joint surface. Both types of tears are well demonstrated on MRI scans.
Fractures and Bone Bruises
Generally, fractures are diagnosed by routine x-ray examination. However, some very subtle fractures are not detectable on plain x-ray films. In these cases, MRI can be more sensitive to these type of fractures, and can be useful in difficult cases. Similarly, bone bruises, which can be very painful, are invisible on x-rays, but are easily detected by MRI.
Muscle Strains and Tears
Tears and strains of muscle are usually diagnosed on a clinical basis, without the use of imaging tests. However, in elite athletes, where precise diagnosis is critical, MRI may be used to assess the extent of a strain, and to look for more serious tears. MRI results are useful in planning the rehabilitation of muscle injuries, and estimating the time to return to the playing field.
Steven M. Cohen - Dr. Steven Cohen is a practicing physician, specializing in Diagnostic Radiology. Dr. Cohen, a member of the American College of Sports ...
