News Release

MLB 'FEVER' -- improved elbow MRI view for Major League Baseball pitchers

Flexed elbow valgus external rotation (FEVER) view improves MRI evaluation of ulnar collateral ligament in Major League Baseball throwing athletes

Peer-Reviewed Publication

American Roentgen Ray Society

Side View of Volunteer Demonstrating Proper Positioning for FEVER View

image: Note elevated flexed elbow and sandbags to induce valgus stress. Elbow coil is not included in image. view more 

Credit: American Roentgen Ray Society (ARRS), <em>American Journal of Roentgenology</em> (AJR)

Leesburg, VA, June 4, 2021--According to a pilot study published in ARRS' American Journal of Roentgenology (AJR), the flexed elbow valgus external rotation (FEVER) view can improve MRI evaluation of the ulnar collateral ligament (UCL) in Major League Baseball (MLB) pitchers.

"The increased joint space width confirms elbow valgus stress with FEVER view," wrote corresponding author Thomas Knoblauch at the University of Nevada Las Vegas. "Diagnostic confidence increased, and additional UCLs were identified as abnormal."

Due to repetitive extreme valgus stress during overhead throwing maneuvers, UCL injuries remain common in throwing athletes. Because standard positioning for elbow MRI is often suboptimal for UCL rendering, Knoblauch, Arizona Diamondbacks head team physician Gary Waslewski, and colleagues piloted their study to assess FEVER view impact on ulnotrochlear (UT) joint space measurement and UCL reader evaluation, as incorporated with conventional elbow MRI.

A total of 44 MLB pitchers underwent elbow MRI, including both standard sequences and a coronal fat-saturated proton density-weighted sequence in the FEVER view using specific positioning maneuvers and sandbags to immobilize the elbow in valgus stress, while visualizing the UCL parallel to its long axis. To measure UT joint space and assess confidence in UCL-related findings with overall UCL normality, two radiologists independently evaluated standard and FEVER views.

"Among 44 MLB pitchers undergoing elbow MRI," Knoblauch et al. continued, "the FEVER view, compared with standard view, yielded increased UT joint space width (mean increase, 1.80 mm) and increased confidence for three of five UCL-related findings (mean increase, -0.14 to 0.98)." Readers 1 and 2 classified 3 and 2 additional UCLs as abnormal on FEVER compared with standard view; neither reader classified any UCL as abnormal in standard view but normal in FEVER view.

"The findings support the FEVER view as a practical addition to standard elbow MRI protocols for achieving elbow valgus stress in throwing athletes," the authors of this AJR article concluded, "thereby providing functional information to complement the high-resolution anatomic assessment provided by MRI."


Founded in 1900, the American Roentgen Ray Society (ARRS) is the first and oldest radiological society in North America, dedicated to the advancement of medicine through the profession of radiology and its allied sciences. An international forum for progress in medical imaging since the discovery of the x-ray, ARRS maintains its mission of improving health through a community committed to advancing knowledge and skills with an annual scientific meeting, monthly publication of the peer-reviewed American Journal of Roentgenology (AJR), quarterly issues of InPractice magazine, AJR Live Webinars and Podcasts, topical symposia, print and online educational materials, as well as awarding scholarships via The Roentgen Fund®.

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