Magnetic Resonance Elastography of Intervertebral Discs: Spin‐<scp>Echo Echo</scp>‐Planar Imaging Sequence Validation

Co, Megan; Dong, Haitao; Boulter, Daniel; Nguyen, Xuan V.; Khan, Safdar N.; Raterman, Brian; Klamer, Brett; Kolipaka, Arunark; Walter, Benjamin A.

doi:10.1002/jmri.28151

Cited by 3 publications

(6 citation statements)

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“…This study is the first to extend the range of frequency sweep testing to 100 Hz allowing for the comparison between MRE‐derived and rheometry‐derived shear moduli of NP tissue at similar frequencies. Average MRE‐derived measurements of 12.3 ± 2.7 kPa for 5% PEG samples and 17.5 ± 3.4 kPa for 25% PEG samples at 80 Hz were of a similar range to in vivo MRE‐derived measurements at varying degeneration levels at the same frequency from prior literature 15,16 …”

Section: Discussionsupporting

confidence: 68%

“…Average MRE‐derived measurements of 12.3 ± 2.7 kPa for 5% PEG samples and 17.5 ± 3.4 kPa for 25% PEG samples at 80 Hz were of a similar range to in vivo MRE‐derived measurements at varying degeneration levels at the same frequency from prior literature. 15 , 16 …”

Section: Discussionmentioning

confidence: 99%

“…80 Hz was utilized as previous studies have performed MRE on IVDs at that frequency for adequate wave penetration and wavelength estimation. 15 , 16 100 Hz was utilized as a point of comparison and because it was the highest frequency within the limits of both the MRE driver and rheometer. SE‐EPI sequences capturing individual (SE‐EPI_i/n = 20 IVDs) or multiple (SE‐EPI_m/n = 6 IVDs) discs embedded within agarose were used with slight differences in parameters based on the different number of slices.…”

Section: Methodsmentioning

confidence: 99%

“…A spin‐echo echo‐planar imaging (SE‐EPI) MRE sequence at 80 and 100 Hz was used to assess shear modulus. 80 Hz was utilized as previous studies have performed MRE on IVDs at that frequency for adequate wave penetration and wavelength estimation 15,16 . 100 Hz was utilized as a point of comparison and because it was the highest frequency within the limits of both the MRE driver and rheometer.…”

Section: Methodsmentioning

confidence: 99%

“…Magnetic resonance elastography (MRE) is an imaging technique capable of assessing changes in shear mechanical properties with disease and has been applied to a variety of soft tissues including the heart, brain, and liver. 6 , 7 , 8 , 9 , 10 Multiple studies have utilized MRE on the IVD and demonstrated its potential to assess disease‐related changes in shear properties 11 , 12 , 13 , 14 , 15 , 16 ; However, it remains unclear how representative MRE measures of IVD shear modulus are compared with those derived from torsional mechanical testing. MRE‐derived measurements have been compared with those derived from rheometry in the liver where there is ample tissue for both MRE and rheological assessment and demonstrated good agreement between techniques.…”

Section: Introductionmentioning

confidence: 99%

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Nucleus pulposus structure and function assessed in shear using magnetic resonance elastography, quantitative MRI, and rheometry

Co,

Raterman,

Klamer

et al. 2024

JOR Spine

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BackgroundIn vivo quantification of the structure–function relationship of the intervertebral disc (IVD) via quantitative MRI has the potential to aid objective stratification of disease and evaluation of restorative therapies. Magnetic resonance elastography (MRE) is an imaging technique that assesses tissue shear properties and combined with quantitative MRI metrics reflective of composition can inform structure–function of the IVD. The objectives of this study were to (1) compare MRE‐ and rheometry‐derived shear modulus in agarose gels and nucleus pulposus (NP) tissue and (2) correlate MRE and rheological measures of NP tissue with composition and quantitative MRI.MethodMRE and MRI assessment (i.e., T1ρ and T2 mapping) of agarose samples (2%, 3%, and 4% (w/v); n = 3–4/%) and of bovine caudal IVDs after equilibrium dialysis in 5% or 25% PEG (n = 13/PEG%) was conducted. Subsequently, agarose and NP tissue underwent torsional mechanical testing consisting of a frequency sweep from 1 to 100 Hz at a rotational strain of 0.05%. NP tissue was additionally evaluated under creep and stress relaxation conditions. Linear mixed‐effects models and univariate regression analyses evaluated the effects of testing method, %agarose or %PEG, and frequency, as well as correlations between parameters.ResultsMRE‐ and rheometry‐derived shear moduli were greater at 100 Hz than at 80 Hz in all agarose and NP tissue samples. Additionally, all samples with lower water content had higher complex shear moduli. There was a significant correlation between MRE‐ and rheometry‐derived modulus values for homogenous agarose samples. T1ρ and T2 relaxation times for agarose and tissue were negatively correlated with complex shear modulus derived from both techniques. For NP tissue, shear modulus was positively correlated with GAG/wet‐weight and negatively correlated with %water content.ConclusionThis work demonstrates that MRE can assess hydration‐induced changes in IVD shear properties and further highlights the structure–function relationship between composition and shear mechanical behaviors of NP tissue.

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Section: Discussionsupporting

confidence: 68%

Section: Discussionmentioning

confidence: 99%