Magnetic resonance imaging of graded skeletal muscle injury in live rats.


INTRODUCTION: Increasing number of stretch-shortening contractions (SSCs) results in increased muscle injury. METHODS: Fischer Hybrid rats were acutely exposed to an increasing number of SSCs in vivo using a custom-designed dynamometer. Magnetic resonance imaging (MRI) imaging was conducted 72 hours after exposure when rats were infused with Prohance and imaged using a 7T rodent MRI system (GE Epic 12.0). Images were acquired in the transverse plane with typically 60 total slices acquired covering the entire length of the hind legs. Rats were euthanized after MRI, the lower limbs removed, and tibialis anterior muscles were prepared for histology and quantified stereology. RESULTS: Stereological analyses showed myofiber degeneration, and cellular infiltrates significantly increased following 70 and 150 SSC exposure compared to controls. MRI images revealed that the percent affected area significantly increased with exposure in all SSC groups in a graded fashion. Signal intensity also significantly increased with increasing SSC repetitions. DISCUSSION: These results suggest that contrast-enhanced MRI has the sensitivity to differentiate specific degrees of skeletal muscle strain injury, and imaging data are specifically representative of cellular histopathology quantified via stereological analyses.





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Publication Info

Cutlip, Robert G, Melinda S Hollander, G Allan Johnson, Brice W Johnson, Sherri A Friend and Brent A Baker (2014). Magnetic resonance imaging of graded skeletal muscle injury in live rats. Environ Health Insights, 8(Suppl 1). pp. 31–39. 10.4137/EHI.S15255 Retrieved from

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G. Allan Johnson

Charles E. Putman University Distinguished Professor of Radiology

Dr. Johnson is the Charles E. Putman University Professor of Radiology, Professor of Physics, and Biomedical Engineering, and Director of the Duke Center for In Vivo Microscopy (CIVM). The CIVM is an NIH/NIBIB national Biomedical Technology Resource Center with a mission to develop novel technologies for preclinical imaging (basic sciences) and apply the technologies to critical biomedical questions. Dr. Johnson was one of the first researchers to bring Paul Lauterbur's vision of magnetic resonance (MR) microscopy to practice as described in his paper, "Nuclear magnetic resonance imaging at microscopic resolution" (J Magn Reson 68:129-137, 1986). Dr. Johnson is involved in both the engineering physics required to extend the resolution of MR imaging and in a broad range of applications in the basic sciences.

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