Related Experiment Video
Updated: May 5, 2026
02:58
Measurement of Compressive Stress-Strain Response at Small-Strains
Published on: December 5, 2025
481
Intervertebral Disc Elastography to Relate Shear Modulus and Relaxometry in Compression and Bending.
Zachary R Davis1, P Cameron Gossett1, Robert L Wilson2
1Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907-2032, USA.
Bioengineering (Basel, Switzerland)
|May 4, 2026
Summary
Intervertebral disc degeneration causes low back pain. This study found MRI relaxometry (T1, T2) and image-based elastography are complementary for assessing disc degeneration, though correlations varied by loading mode.
Area of Science:
- Biomedical Engineering
- Radiology
- Orthopedics
Background:
- Intervertebral disc degeneration is a primary cause of low back pain, involving tissue structural and mechanical decline.
- Current assessment methods for disc degeneration lack ideal functional evaluation.
- Image-based mechanical parameters and MRI relaxometry show potential for assessing disc degeneration but require further development and validation.
Purpose of the Study:
- To quantify T1 and T2 relaxation times in human cadaveric discs.
- To compare MRI-derived relaxation times with in-plane strains and estimated shear moduli under compression and bending.
- To investigate the potential of MRI relaxometry and image-based elastography for assessing disc degeneration.
Main Methods:
- Quantified T1 and T2 relaxation times in human cadaveric discs.
- Measured in-plane strains using displacement-encoded MRI under compression and bending.
- Estimated shear modulus using a novel inverse approach and compared with relaxation times and strains.
Main Results:
- Intratissue strain varied with loading mode (compression vs. bending).
- Shear modulus in the nucleus pulposus was significantly lower than in the annulus fibrosus.
- Limited correlation was found between shear modulus and MRI relaxometry (T1, T2), with only one significant instance (T1 vs. relative shear modulus in the coronal plane under bending).
Conclusions:
- Image-based elastography and MRI relaxometry are complementary tools for assessing disc structure and function.
- Future inverse analyses should incorporate multiple loading conditions for improved accuracy.
- Further research is needed to fully integrate these imaging techniques for comprehensive disc degeneration assessment.
Related Concept Videos
01:15Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
824
Deformation occurs in axial and transverse directions when an axial load is applied to a slender bar. This deformation impacts the cubic element within the bar, transforming it into either a rectangular parallelepiped or a rhombus, contingent on its orientation. This transformation process induces shearing strain. Axial loading elicits both shearing and normal strains. Applying an axial load instigates equal normal and shearing stresses on elements oriented at a 45° angle to the load axis.
824
01:15Strain and Elastic Modulus
6.3K
The quantity that describes the deformation of a body under stress is known as strain. Strain is given as a fractional change in either length, volume, or geometry under tensile, volume (also known as bulk), or shear stress, respectively, and is a dimensionless quantity. The strain experienced by a body under tensile or compressive stress is called tensile or compressive strain, respectively. In contrast, the strain experienced under bulk stress and shear stress is known as volume and shear...
6.3K
01:20Elastic Strain Energy for Shearing Stresses
668
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...
668
01:20Elasticity in Concrete
535
Upon subjecting concrete to moderate or high uniaxial compressive or tensile stresses, the strain response is non-linear relative to the stress applied. As the stress is removed, the resulting stress-strain curve deviates from the original path traced during loading, creating a hysteresis loop, indicative of the concrete's non-linear and non-elastic properties. Typically, a material's modulus of elasticity, which is a measure of the material's stiffness, is inferred from the linear...
535
01:18Residual Stresses in Bending
688
In the study of elastoplastic members subjected to bending moments, understanding the loading and unloading phases is crucial for assessing material behavior and structural integrity. During the loading phase, as the bending moment increases, the material initially responds elastically, adhering to Hooke's Law, where stress is directly proportional to strain. When the load exceeds the yield strength, plastic deformation occurs, resulting in permanent strain and deformation that remains even...
688
01:16Dynamic Modulus of Elasticity of Concrete
1.3K
The dynamic modulus of elasticity assesses how a concrete structure deforms under impact or dynamic loads. It is typically higher than the static modulus of elasticity, measured under slow, steady loading conditions.
The sonic test is a common method to determine the dynamic modulus. In this test, a concrete beam, sized either 6 x 6 x 30 inches or 4 x 4 x 20 inches, is clamped at its center. Vibrations are initiated at one end of the beam by an electromagnetic exciter unit powered by a...
The sonic test is a common method to determine the dynamic modulus. In this test, a concrete beam, sized either 6 x 6 x 30 inches or 4 x 4 x 20 inches, is clamped at its center. Vibrations are initiated at one end of the beam by an electromagnetic exciter unit powered by a...
1.3K