Quantitative MRI Reveals Microstructural Changes in the Upper Leg Muscles After Running a Marathon

Area of Science:

• Radiology and Imaging
• Sports Medicine
• Muscle Physiology

Background:

• Sports injuries frequently involve skeletal muscle, with exercise-induced microtrauma often being subclinical and hard to detect.
• Current methods struggle to identify and pinpoint subtle muscle damage from exercise.
• Developing advanced techniques for detecting exercise-induced muscle microtrauma is crucial.

Purpose of the Study:

• To evaluate microstructural changes in upper leg muscles using multiparametric quantitative MRI.
• To assess both acute and delayed changes following marathon running.
• To investigate the utility of MRI in detecting exercise-induced muscle microtrauma.

Main Methods:

• A longitudinal study involving 11 male participants (47-68 years) scanned 1 week before, 24-48 hours after, and 2 weeks after a marathon.
• Multiparametric quantitative MRI using spin-echo echo planar imaging (SE-EPI) with diffusion weighting, multispin echo, Dixon, and fat-suppressed turbo spin-echo (TSE) sequences at 3T.
• Analysis included diffusion parameters (MD, RD, λ3), quantitative T2 (qT2) values, perfusion fractions, and TSE image scoring for injury, with specific focus on segmented muscle analysis (vastus medialis, biceps femoris long head).

Main Results:

• Creatine kinase (CK) levels significantly increased post-marathon and returned to baseline by 2 weeks.
• Most MRI diffusion indices and qT2 values showed significant changes at 24-48 hours post-marathon, returning to baseline by follow-up.
• Localized muscle segment analysis revealed more pronounced microstructural changes (2-3 fold) compared to whole-muscle assessments.

Conclusions:

• Multiparametric quantitative MRI effectively detects marathon running-induced muscle microtrauma.
• MRI can identify both acute and delayed microstructural changes in skeletal muscle.
• Segmented analysis of muscle provides a more sensitive method for detecting localized exercise-induced damage.