Context: Hamstring injuries are frequently observed in various sports disciplines both in elite and recreational sport. Objective: To quantify intramuscular tissue perfusion via contrast-enhanced ultrasound in the acute phase and during the healing of a structural muscle injury confirmed by high-resolution magnetic resonance imaging. Design: Case study. Setting: Laboratory environment. Patient: A 32-year-old wakeboarder (height = 176 cm, body weight = 76 kg, and body mass index = 24.5 kg/m2) with an acute indirect muscle injury of the semimembranosus muscle. Main Outcome Measures: Average values of quantifiable contrast-enhanced ultrasound, represented as peak enhancement and wash-in area under the curve, as well as conventional ultrasound, 1.5T magnetic resonance imaging were assessed at 48-hour, 3-week, and 8-week postinjury. Results: Average values of the quantitative perfusion analysis at 48-hour and 8-week postinjury revealed an approximate 5-fold increase in peak enhancement, and the wash-in area under the curve increased more than 3-fold in the center of the lesion. Magnetic resonance imaging, performed 48 hours after the injury to gather reference data as gold standard, revealed a grade III structural muscle tear. Conclusions: The authors are able to demonstrate significant changes in intramuscular tissue perfusion in the center of the structural lesion as well as in the adjacent tissue. Quantifiable contrast-enhanced ultrasound seems to be able to gather relevant data for the assessment and monitoring of muscle injuries and could be established as a valuable tool for further studies focusing on healing processes or therapeutic interventions.
Marion Kellermann, Christoph Lutter and Thilo Hotfiel
Thilo Hotfiel, Marion Kellermann, Bernd Swoboda, Dane Wildner, Tobias Golditz, Casper Grim, Martin Raithel, Michael Uder and Rafael Heiss
Context: Delayed onset muscle soreness is one of the most common reasons for impaired muscle performance in sports and is associated with reduced muscle strength and frequently observed both in professional and recreational athletes. Objective: To emphasize the diagnostic value of acoustic radiation force impulse (ARFI) in imaging of delayed onset muscle soreness by comparing findings with high-resolution 3T magnetic resonance imaging T2-weighted sequences. Design: Case series. Setting: Laboratory environment. Participants: Fifteen healthy students (7 females and 8 males; mean [SD]: age 24  y, height 178  cm, body weight 67  kg). Main Outcome Measures: ARFI values, represented as shear wave velocities of the gastrocnemius muscle and soleus muscle, as well as conventional ultrasound, high-resolution 3T magnetic resonance imaging, creatine kinase activity, extension range of the ankle joint, calf circumference, and muscle soreness were assessed before (baseline) and 60 hours after (postintervention) a standardized eccentric exercise. Results: ARFI shear wave velocity values of the gastrocnemius muscle revealed a statistically significant decrease of 19.1% between baseline (2.2 [0.26] m/s) and postintervention (1.78 [0.24] m/s); P = .01. At follow-up, the magnetic resonance imaging investigations showed intramuscular edema for the gastrocnemius muscle in all participants corresponding to a significant raise in T2 signal intensity (P = .001) and in T2-time values (P = .004). Conclusions: ARFI elastography seems to be an additional sensitive diagnostic modality in the diagnostic workup of delayed onset muscle soreness. Intramuscular shear wave velocities could represent an additional imaging marker for the assessment and monitoring of ultrastructural muscle injuries and therefore be helpful for individual training composition in elite sports.