MRE setup placed inside a 1.5 T MRI machine.

<p><b>A:</b> A participant laid supine on a custom-built ergometer to characterize the quadriceps (VL, RF, VI, and VM) and sartorius (Sr) muscles. <b>B:</b> Participant laid on his abdomen to analyze the ischio (ST, SM, BC) and gracilis (Gr) muscles. Waves were generated at 90 Hz through a pneumatic driver (silicon tube) attached around the thigh muscles, where a coil was placed. VL: vastus lateralis, RF: rectus femoris, VI: vastus intermedius, VM: vastus medialis, Sr: sartorius, ST: semitendinosus, SM: semimembranosus, BC: biceps, Gr: gracilis.</p

Shear modulus (μ) with SEM obtained for the different thigh muscles and adipose tissues.

<p>VL: vastus lateralis, RF: rectus femoris, VI: vastus intermedius, VM: vastus medialis, Sr: sartorius, ST: semitendinosus, SM: semimembranosus, BC: biceps, Gr: gracilis. *: significantly different to all tissues (<i>P</i> < 0.04). Φ: significantly different to all tissues except ST (<i>P</i> < 0.03). π: significantly different to all tissues except Sr (<i>P</i> < 0.03). α: significantly different to Gr, Sr, ST and adipose tissue (<i>P</i> < 0.04). Ø: significantly different to all muscles (<i>P</i> < 0.01).</p

Visualization of clear and unclear wave propagation.

<p>A: Axial image with two different orientations of the imaging planes (IP#2, IP#3) through semimembranosus (SM) and semitendinosus (ST). Phase images showing clear (B) wave with measurable wavelength (λ) (C) and unclear (D) waves with non measurable wavelength (E). P1: Profile 1, P2: Profile 2.</p

Quantifying the Elastic Property of Nine Thigh Muscles Using Magnetic Resonance Elastography

<div><p>Background</p><p>Pathologies of the muscles can manifest different physiological and functional changes. To adapt treatment, it is necessary to characterize the elastic property (shear modulus) of single muscles. Previous studies have used magnetic resonance elastography (MRE), a technique based on MRI technology, to analyze the mechanical behavior of healthy and pathological muscles. The purpose of this study was to develop protocols using MRE to determine the shear modulus of nine thigh muscles at rest.</p><p>Methods</p><p>Twenty-nine healthy volunteers (mean age = 26 ± 3.41 years) with no muscle abnormalities underwent MRE tests (1.5 T MRI). Five MRE protocols were developed to quantify the shear moduli of the nine following thigh muscles at rest: rectus femoris (RF), vastus medialis (VM), vastus intermedius (VI), vastus lateralis (VL), sartorius (Sr), gracilis (Gr), semimembranosus (SM), semitendinosus (ST), and biceps (BC). In addition, the shear modulus of the subcutaneous adipose tissue was analyzed.</p><p>Results</p><p>The gracilis, sartorius, and semitendinosus muscles revealed a significantly higher shear modulus (μ_{_Gr} = 6.15 ± 0.45 kPa, μ_{_ Sr} = 5.15 ± 0.19 kPa, and μ_{_ ST} = 5.32 ± 0.10 kPa, respectively) compared to other tissues (from μ_{_ RF} = 3.91 ± 0.16 kPa to μ_{_VI} = 4.23 ± 0.25 kPa). Subcutaneous adipose tissue had the lowest value (μ_{_adipose tissue} = 3.04 ± 0.12 kPa) of all the tissues tested.</p><p>Conclusion</p><p>The different elasticities measured between the tissues may be due to variations in the muscles' physiological and architectural compositions. Thus, the present protocol could be applied to injured muscles to identify their behavior of elastic property. Previous studies on muscle pathology found that quantification of the shear modulus could be used as a clinical protocol to identify pathological muscles and to follow-up effects of treatments and therapies. These data could also be used for modelling purposes.</p></div

Behavior of the shear wave along the prescribed profile.

<p>The gracilis (Gr) muscle revealed a higher wavelength (λ) compared to the rectus femoris (RF) muscle.</p