Correlation of transverse relaxation time with structure of biological tissue

Furman, G. B.; Meerovich, V.

doi:10.1016/j.jmr.2016.06.018

Cited by 16 publications

(33 citation statements)

References 18 publications

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“…Let us determine the deviation of the main axis of each collagen fibril from the Z 0 direction by the polar angle β and azimuthal angle δ. Angular distributions of nanocavities are determined by the anatomical structure of a tested sample. Analysis of data presented in literature showed that the Gaussian distribution well approximates the anatomical structure [25,26]. In these works, using the distribution approximation the agreement between the theoretical model and experiments for the relaxation rates, T 1 −1 and T 2 −1 was achieved.…”

Section: Relaxation Rate Under Spin Lockingmentioning

confidence: 79%

“…The procedure of averaging of DDI between spins inside a nanocavity [25,26] considers a system consisting of N nuclear spins, I = 1/2, enclosed in a nanocavity in an external field H 0 directed along the z -axis. The Hamiltonian of the spin system written in units of frequency can be presented as [1,2]…”

Section: Averaging Of Ddi Between Spins Inside Nanocavitiesmentioning

confidence: 99%

“…Many fibril biological and human tissues possess a hierarchical structure with characteristic diameters from ~1 nm to several tens of nm and length on the order of 300 nm [12, page 12]. The theoretical predictions for the transverse relaxation time T 2 have been confirmed by comparison with experimental data [25,26]. In these works, tissues were represented as a set of the elongated nanocavities which are formed by the fibril structure and contain water.…”

Section: Averaging Of Ddi Between Spins Inside Nanocavitiesmentioning

confidence: 99%

“…To explain the anisotropy effects of the local dipolar field and transverse relaxation time in fibril structures, a model of liquid entrapped in nanocavities has been developed [25,26]. This model is based on averaging of the dipole-dipole interaction (DDI) between spin pairs with taking into account a restricted molecule motion [27,28].…”

Section: Introductionmentioning

confidence: 99%

“…This model is based on averaging of the dipole-dipole interaction (DDI) between spin pairs with taking into account a restricted molecule motion [27,28]. The averaging gives that DDI between any spin pair is characterized by a single effective constant, which depends on the cavity orientation relative to the magnetic field H 0 as well as the cavity form and volume [7][8][9][10][11][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Spin locking in liquid entrapped in nanocavities: Application to study connective tissues

Furman

Meerovich

Xia

2019

Journal of Magnetic Resonance

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Study of the spin-lattice relaxation in the spin-locking state offers important information about atomic and molecular motions, which cannot be obtained by spin lattice relaxation in strong external magnetic fields. The application of this technique for the investigation of the spin-lattice relaxation in biological samples with fibril structures reveals an anisotropy effect for the relaxation time under spin locking, T 1ρ. To explain the anisotropy of the spin-lattice relaxation under spinlocking in connective tissue a model which represents a tissue by a set of nanocavities containing water is used. The developed model allows us to estimate the correlation time for water molecular motion in articular cartilage, τ c = 30 μs and the averaged nanocavity volume, 〈V〉 ≃ 5400 nm 3. Based on the developed model which represents a connective tissue by a set of nanocavities containing water, a good agreement with the experimental data from an articular cartilage and a tendon was demonstrated. The fitting parameters were obtained for each layer in each region of the articular cartilage. These parameters vary with the known anatomic microstructures of the tissue. Through Gaussian distributions to nanocavity directions, we have calculated the anisotropy of the relaxation time under spin locking T 1ρ for a human Achilles tendon specimen and an articular cartilage. The value of the fitting parameters obtained at matching of calculation to experimental results can be used in future investigations for characterizing the fine fibril structure of biological samples.

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Section: Relaxation Rate Under Spin Lockingmentioning

confidence: 79%

Section: Averaging Of Ddi Between Spins Inside Nanocavitiesmentioning

confidence: 99%

Section: Averaging Of Ddi Between Spins Inside Nanocavitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spin locking in liquid entrapped in nanocavities: Application to study connective tissues

Furman

Meerovich

Xia

2019

Journal of Magnetic Resonance

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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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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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Microscopic theory of spin–spin and spin–lattice relaxation of bound protons in cellular and myelin membranes—A lateral diffusion model (LDM)

Sukstanskiı̆

Yablonskiy

2022

Magnetic Resonance in Med

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Deciphering salient features of biological tissue cellular microstructure in health and diseases is an ultimate goal of MRI. While most MRI approaches are based on studying MR properties of tissue "free" water indirectly affected by tissue microstructure, other approaches, such as magnetization transfer (MT), directly target signals from tissue-forming macromolecules. However, despite three-decades of successful applications, relationships between MT measurements and tissue microstructure remain elusive, hampering interpretation of experimental results. The goal of this paper is to develop microscopic theory connecting the structure of cellular and myelin membranes to their MR properties.Theory and Methods: Herein we introduce a lateral diffusion model (LDM) that explains the T 2 (spin-spin) and T 1 (spin-lattice) MRI relaxation properties of the macromolecular-bound protons by their dipole-dipole interaction modulated by the lateral diffusion of long lipid molecules forming cellular and myelin membranes. Results: LDM predicts anisotropic T 1 and T 2 relaxation of membrane-bound protons. Moreover, their T 2 relaxation cannot be described in terms of a standard R 2 = 1/T 2 relaxation rate parameter, but rather by a relaxation rate function R 2 (t) that depends on time t after RF excitation, having, in the main approximation, a logarithmic behavior: R 2 (t) ∼ lnt. This anisotropic non-linear relaxation leads to an absorption lineshape that is different from Super-Lorentzian traditionally used in interpreting MT experiments. Conclusion: LDM-derived analytical equations connect the membrane-boundprotons T 1 and T 2 relaxation with dynamic distances between protons in neighboring membrane-forming lipid molecules and their lateral diffusion. This sheds new light on relationships between MT parameters and microstructure of cellular and myelin membranes.

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Correlation of transverse relaxation time with structure of biological tissue

Cited by 16 publications

References 18 publications

Spin locking in liquid entrapped in nanocavities: Application to study connective tissues

Spin locking in liquid entrapped in nanocavities: Application to study connective tissues

Orientation anisotropy of quantitative MRI parameters in degenerated human articular cartilage

Microscopic theory of spin–spin and spin–lattice relaxation of bound protons in cellular and myelin membranes—A lateral diffusion model (LDM)

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