Daily Bulletin 2016

Protocols Focused on Detection of Injury, Adaptation in Young Athletes

Tuesday, Nov. 29, 2016

Early detection of stress injuries and overuse changes in adolescent
athletes may lead to improved treatment and allow for new training guidelines. Two studies presented Monday evaluated techniques designed to examine young athletes with the aim of optimizing imaging methods and slowing injury progression.

MRI Technique Offers Improved View of Physeal Changes

Cartilage-sensitive MRI images illustrating a severe case of radial epiphysitis

(Click to enlarge) Cartilage-sensitive MRI images illustrating a severe case of radial epiphysitis in a gymnast with wrist pain (left), and a more subtle change with intrusion of the growth plate cartilage into the metaphysis in an asymptomatic gymnast (center). The healthy physis of a non-gymnast child (right).

Researchers at Academic Medical Center in Amsterdam explored the use of MRI over conventional radiography to identify subtle stress changes of the distal radial growth plate in young gymnasts with the hope of diagnosing growth plate injury at an earlier stage.

Radial epiphysitis or "gymnast wrist" is an injury requiring long recovery periods and causing long-term degeneration of the wrist joint. Laura Kox, MD, reported that while conventional radiology can be used to identify severe cases of gymnast wrist, "MRI is capable of depicting more subtle changes because of its ability to image cartilage and bone marrow edema."

Laura Kox, MD

Laura Kox, MD

Dr. Kox and her colleagues established a series of test sequences examining the distal radial physes to identify the aspects typical for symptomatic gymnasts, asymptomatic gymnasts and non-gymnastic controls. They examined 19 gymnasts with wrist pain, five without wrist pain and five non-gymnasts between the ages of 12 and 17 years.

All participants underwent radiography and MRI of the wrist. MRI was performed on a 3T scanner and included coronal proton density (PD) images with and without fat saturation as well as 3-D WATSc and TI-weighted and T2-weighted Dixon series.

An experienced musculoskeletal radiologist evaluated the appearance of the physes and 3-D reconstructions were created for analysis. The water fraction in the adjacent metaphyseal bone was quantified using Dixon water-only images. Magnetic resonance images of symptomatic gymnasts were compared with those of asymptomatic and non-gymnast controls.

The results show that the median volume of the physis of symptomatic gymnasts was 817 mm3 compared to 829 mm3 in asymptomatic gymnasts. The median water fraction in the metaphysis was 38 percent for symptomatic gymnasts and only 30 percent in those that were asymptomatic. Thus the water fraction method proved more useful in discerning changes in gymnasts' wrists.

Other abnormalities were found in both groups such as metaphyseal intrusions and disruption of the physeal layer, but these were not recognized on the radiographic images. The results emphasize the importance of MRI in early diagnosis of physeal stress injury.

Dr. Kox and her team plan to expand their research to a larger population in the hope of evaluating the effect of rest on the growth plate and applying their findings to provide treatment information for their patients.

Finer Adaptive and Overuse Changes Identified through Ultrasound Exam

In a similar study, presenter Kathryn Garcia, high school intern at Stanford University, and her fellow researchers at Stanford Children's Hospital used ultrasound (US) to assess for differences in thickness of soft tissue, flexor and extensor tendons and volar plate as well as bony and physeal deformities in adolescent rock climbers.

Kathryn Garcia

Kathryn Garcia

Garcia and her team examined the third and fourth digits of the right hands of 20 adolescent rock climbers (ages 10-18) and six non-climbing, age-matched control subjects. The climbers were grouped into three levels based on the number of hours/week, years of climbing and preferred climbing technique with Level 3 representing the most intense training.

Findings revealed adaptations correlating with training intensity including significant soft tissue hypertrophy of the flexor compartment and bony remodeling compared to non-climbing controls. In all, 53 percent of climbers in the study also demonstrated overuse injuries, likely due to repetitive trauma and imbalance of mechanical force.

Compared with non-climbing control subjects, climbers demonstrated significantly thicker flexor tendons, MCP volar plates and soft tissues (all p<0.05). Climbers also had comparatively larger bony tubercles at flexor digitorum profundus insertion.

"We discovered some unexpected injuries in the physis, such as fractures and deformities," says Garcia. "We also found more phalangeal malalignment in the fingers of young climbers than expected."

Joint effusions were found in 68 percent of climbers while significant phalangeal malalignment was seen in 53 percent. Physeal deformities were identified in four climbers, all of whom were Level 3 climbers. The findings show that more training can lead to more significant damage over time regardless of intensity.

Responding to an audience question about MRI correlation of the US study results, Erika Rubesova, MD, a study author, said MRI correlated to the US findings showing the thickness changes, but the sampling was too small and requires an additional study with a larger population.

Garcia said she plans to perform follow-up examinations of the climbers to evaluate the progression or improvement of injuries with a change of training practices. "Long term, we hope to develop guidelines for the training of young rock climbers," she added.

Question of the Day:

I want to buy a new mammography unit, but it has a tungsten target. Don't I need the characteristic x-rays from Molybdenum to have the optimal energy range for breast imaging?

Tip of the day:

Dose alerts are set for equipment as a complete unit. This means it may help prevent overdosing a patient, but it also means that the alert may kick in during a high-dose procedure like CT-fluoroscopy and interrupt imaging. Always make sure someone in the room has the password to override when performing high dose procedures on dose alert enabled equipment.

The RSNA 2016 Daily Bulletin is owned and published by the Radiological Society of North America, Inc., 820 Jorie Blvd., Oak Brook, IL 60523.