Physical Properties of Cartilage by Relaxation Anisotropy

Nieminen, Miika T.; Nissi, Mikko J.; Hanni, Matti; Xia, Yang

doi:10.1039/9781782623663-00145

Cited by 5 publications

(9 citation statements)

References 155 publications

(200 reference statements)

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“…Generally, it is believed that the organization and alignment of collagen fibers create the orientation dependent properties of cartilage 18 . Xia 21 suggested in 1998 that proteoglycans might have an effect on orientation anisotropy, and later he phrases a possible explanation 49 that “although the T 2 ‐anisotropic characteristic of cartilage is linked to the collagen fibril orientation in the tissue, the water‐proteoglycan interaction influences the mobility of most water and “amplifies” the prevailing directional orientation of collagen fibers to make it measurable by NMR.” Trypsin digestion can be used to deplete proteoglycans from the samples, but in one study the trypsin treatment alone did not make the relaxation anisotropy disappear in the case of intact cartilage samples 50 .…”

Section: Discussionmentioning

confidence: 99%

“…shown to be sensitive to tissue orientation in the main magnetic field B 0 , and this directional dependence is called relaxation anisotropy. 18,19 The term "magic angle effect" has been used to describe the specific angle, that is, 54.7°, at which the residual dipolar interaction vanishes and the orientation dependent relaxation times reach their maximum value. 20 Generally, T 1 is not affected by the tissue orientation, 21 while T 2 has the strongest orientation dependence.…”

Section: Multiple Quantitative Mri Relaxation Parameters Have Beenmentioning

confidence: 99%

“…Multiple quantitative MRI relaxation parameters have been shown to be sensitive to tissue orientation in the main magnetic field B 0 , and this directional dependence is called relaxation anisotropy 18,19 . The term “magic angle effect” has been used to describe the specific angle, that is, 54.7°, at which the residual dipolar interaction vanishes and the orientation dependent relaxation times reach their maximum value 20 .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Orientation anisotropy of quantitative MRI parameters in degenerated human articular cartilage

Hänninen

Nykänen

Prakash

et al. 2020

Journal Orthopaedic Research

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Quantitative magnetic resonance (MR) relaxation parameters demonstrate varying sensitivity to the orientation of the ordered tissues in the magnetic field. In this study, the orientation dependence of multiple relaxation parameters was assessed in cadaveric human cartilage with varying degree of natural degeneration, and compared with biomechanical testing, histological scoring, and quantitative histology. Twelve patellar cartilage samples were imaged at 9.4 T MRI with multiple relaxation parameters, including T 1 , T 2 , CW − T 1ρ , and adiabatic T 1ρ , at three different orientations with respect to the main magnetic field. Anisotropy of the relaxation parameters was quantified, and the results were compared with the reference measurements and between samples of different histological Osteoarthritis Research Society International (OARSI) grades. T 2 and CW − T 1ρ at 400 Hz spin-lock demonstrated the clearest anisotropy patterns. Radial zone anisotropy for T 2 was significantly higher for samples with OARSI grade 2 than for grade 4. The proteoglycan content (measured as optical density) correlated with the radial zone MRI orientation anisotropy for T 2 (r = 0.818) and CW − T 1ρ with 400 Hz spin-lock (r = 0.650). Orientation anisotropy of MRI parameters altered with progressing cartilage degeneration. This is associated with differences in the integrity of the collagen fiber network, but it also seems to be related to the proteoglycan content of the cartilage. Samples with advanced OA had great variation in all biomechanical and histological properties and exhibited more variation in MRI orientation anisotropy than the less degenerated samples. Understanding the background of relaxation anisotropy on a molecular level would help to develop new MRI contrasts and improve the application of previously established quantitative relaxation contrasts.

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Section: Discussionmentioning

confidence: 99%

Section: Multiple Quantitative Mri Relaxation Parameters Have Beenmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Orientation anisotropy of quantitative MRI parameters in degenerated human articular cartilage

Hänninen

Nykänen

Prakash

et al. 2020

Journal Orthopaedic Research

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“…As explained in section 2.4, the interactions between spins and their environment cause and modulate relaxation. At the molecular scale, relaxation anisotropy can be attributed to different forms of interactions, such as hindered rotation of molecules, alignment of molecules along fibril structures, compartmentalization of water, and interactions between protein and water molecules (Nieminen, Nissi, Hanni, & Xia, 2017). The exact molecular mechanisms behind relaxation anisotropy are not yet thoroughly known, but the results presented by current research will be discussed here.…”

Section: Background Of Relaxation Anisotropymentioning

confidence: 97%

Relaxation anisotropy of quantitative MRI parameters in biological tissues

Hänninen

Liimatainen

Hanni

et al. 2022

Preprint

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Quantitative MR relaxation parameters vary in their sensitivity to the orientation of the tissue in the magnetic field. In this study, the orientation dependence of multiple relaxation parameters was assessed in various tissues. Ex vivo samples of different tissue types were prepared either from bovine knee (tendon, cartilage) or mouse (brain, spinal cord, heart, kidney), and imaged at 9.4 T MRI with T1, T2, CW-T1ρ, adiabatic T1ρ and T2ρ, and RAFF2-4 sequences at five different orientations with respect to the main magnetic field. Relaxation anisotropy of the measured parameters was quantified and evaluated. Highly ordered collagenous tissues, cartilage and tendon, presented the highest relaxation anisotropy for T2, CW-T1ρ with spin-lock power < 1 kHz, Ad-T2ρ and RAFF2-4. Maximally, anisotropy was 75% in cartilage and 30% in tendon. In the other measured soft tissues, anisotropy was less than 10% for all the parameters. T1 and Ad-T1ρ exhibit little to no observable anisotropy. The results confirm that highly ordered collagenous tissues have properties that induce remarkable relaxation anisotropy, whereas for the other soft tissues investigated, the effect is less prominent. Quantitative comparison of anisotropies between relaxation parameters highlights the importance of sequence choice and design in MR imaging.

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“…The effect has been known in partially hydrated collagen since the early 1960s and was first reported in native biological tissues (mammalian tendon samples) by Fullerton and co-workers in 1985 . The MA effect is now well-known in clinical radiology: it is commonly observed in a range of ordered collagenous tissues, most notably tendon, − articular cartilage, − the intervertebral disc, and as reported recently, the heart muscle . A similar effect, albeit possibly with a different molecular mechanism, has also been reported in brain white matter. − …”

Section: Magnetic Resonance Imaging and The Magic-angle Effectmentioning

confidence: 99%