Feature article

Trends in MR for sports

In the United States from 2011 to 2014, the average number of sports-related injuries was estimated to be roughly 8.6 million, and about half were treated in an emergency department.1 The most common injuries are strains, tears and stress fractures. It is important for patients to remember that the body must heal after an injury and the attending physician may provide a time frame for returning to activity. Many professional athletes experience injuries that require them to stay on the bench for some time. Magnetic resonance imaging (MRI) has become a common way to provide the images physicians need to determine the extent of an injury with high accuracy.

Strains

Due to the stress put on the legs and feet during most sports, the lower limbs are more commonly injured than the upper.2 Among the different types of muscle injury, strain is the most common. A strain is a stretching or tearing of a muscle or tendon (the tissue that connects the muscle to the bone).3 This is similar to a sprain, which affects ligaments instead of muscle. Strains can be acute or chronic depending on the repetition of the injurious activity. Ultrasound often provides the initial assessment of the injury. MR, however, is typically used to confirm an injury and help to evaluate its severity. This is because MR can help doctors visualize the injury due to its ability to visualize soft tissue with high contrast and spatial-resolution. MR is also multi-planar and can show a more well-rounded image. After imaging has been done, the physician may recommend a break from activity, especially for professional athletes.

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Ligament tears

Injuries to the cruciate ligaments are common among athletes, especially those who play sports such as basketball, soccer, football and volleyball.4 A ligament is the band of tissue connecting one bone to another. In the knee, there are a number of different ligaments, including the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL).

Injuries of the anterior ligament are most commonly referred to as ACL tears and result from sports with a lot of jumping and changes in direction, like basketball and volleyball.4 On an MRI image of a normal ACL, it appears as a straight band along the front of the knee.5 A patient may hear or feel a popping in the knee at the time of injury. Often, the pain from an ACL tear may result in an inability to continue playing. Once the ACL has been injured, the appearance would look different on an MR image. T2-weighted imaging sequences show more sensitivity, specificity and accuracy than T1-weighted sequences in regards to an ACL tear. This is because T2-weighted imaging highlights structures with a high concentration of water, such as an inflamed or swollen area. The radiologists read the scans to help them determine the severity of the injury. An acute complete ACL tear is easier for doctors to detect than a chronic ACL disruption. Typically, if a patient has an ACL injury, they may have additional injury to the knee.

The PCL is injured significantly less often and causes less pain or impairment than the ACL.5 Contact sports, like football and soccer, may cause PCL tears during falls or tackles with a bent knee. Like ACL tears, PCL tears may correlate with other injuries to the knee. T2-weighted imaging with an MR is better than T1-weighted imaging for the imaging of the PCL as well. A PCL tear will appear as a break in the band of tissue along the back of the knee and needs rest to heal.

Stress fractures

Tiny cracks in bone, called stress fractures, can be common among athletes who participate in sports with a lot of jumping, such as basketball, dance, and gymnastics.6 Stress fractures occur most often when a person rapidly increases their level of activity or the amount of weight the bone has to support. X-ray, bone scan and MRI often aid a doctor in determining if their patient has a stress fracture.7 MR has no radiation (unlike x-ray and bone scan) and can produce detailed images of internal structures. Fractures can appear within the first week of injury on a scan. Doctors can often distinguish between stress fractures and soft tissue injuries using MRI. Stress reactions, early signs of possible stress fractures, can often be seen and monitored using MRI.

MR has become increasingly helpful for imaging injuries that a physician wants to study in detail. Strains, ligament tears and stress fractures can be monitored by doctors using MRI, which does not use radiation. All of these injuries are most common on the lower limbs and could cause problems walking and remaining active. The doctor may request that their patient take a break from sports in order for the injury to heal. With roughly 8.6 million people injured due to sports each year, including professional athletes who have to continue playing for their career, accurate diagnosis is a necessity.

References

1. "Sports and Recreation-Related Injuries Top 8.6 Million Annually." APTA.org. 4 January 2017. Web. 17 December 2018. <http://www.apta.org/PTinMotion/News/2017/1/4/SportsInjuries/>.

2. Ali Guermazi, et al. “Imaging of Muscle Injuries in Sports Medicine: Sports Imaging Series.” Radiology. 20 February 2017; 282(3). Web. 17 December 2018. <https://pubs.rsna.org/doi/full/10.1148/radiol.2017160267>.

3. Mayo Clinic Staff. "Sprains and strains." MayoClinic.org. 4 October 2017. Web. 18 December 2018. <https://www.mayoclinic.org/diseases-conditions/sprains-and-strains/symptoms-causes/syc-20377938>.

4. Mayo Clinic Staff. "ACL injury." MayoClinic.org. 13 March 2018. Web. 18 December 2018. <https://www.mayoclinic.org/diseases-conditions/acl-injury/symptoms-causes/syc-20350738>.

5. C.K. Kam, et al. "Magnetic Resonance Imaging of Cruciate Ligament Injuries of the Knee." Canadian Association of Radiologists Journal. April 2010; 61(2): 80-89. Web. 18 December 2018. <https://www.sciencedirect.com/science/article/pii/S0846537109002241>.

6. Mayo Clinic Staff. "Stress fractures." MayoClinic.org. 4 August 2017. Web. 18 December 2018. <https://www.mayoclinic.org/diseases-conditions/stress-fractures/diagnosis-treatment/drc-20354063>.

7. Michael Fredericson, et al. "Stress Fractures in Athletes." Topics in Magnetic Resonance Imaging. October 2006; 17(5): 309-325. Web. 18 December 2018. <https://oce.ovid.com/article/00002142-200610000-00002/HTML>.