University of Oulu

Rössler, E, Mattea, C, Saarakkala, S, et al. Correlations of low‐field NMR and variable‐field NMR parameters with osteoarthritis in human articular cartilage under load. NMR in Biomedicine. 2017; 30:e3738. https://doi.org/10.1002/nbm.3738

Correlations of low-field NMR and variable-field NMR parameters with osteoarthritis in human articular cartilage under load

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Author: Rössler, Erik1; Mattea, Carlos1; Saarakkala, Simo2,3;
Organizations: 1Department of Technical Physics II, TU Ilmenau, Ilmenau, Germany
2Research Unit of Medical Imaging, Physics and Technology, University of Oulu, P.O. Box 5000, Oulu, Finland
3Medical Research Center, University of Oulu and Oulu University Hospital, P.O. Box 50, Oulu, Finland
4Department of Diagnostic Radiology, Oulu University Hospital, P.O. Box 50, Oulu, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 0.4 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe2019111438080
Language: English
Published: John Wiley & Sons, 2017
Publish Date: 2019-11-14
Description:

Abstract

NMR experiments carried out at magnetic fields below 1 T provide new relaxation parameters unavailable with conventional clinical scanners. Contrast of T₁ generally becomes larger towards low fields, as slow molecular reorientation processes dominate relaxation at the corresponding Larmor frequencies. This advantage has to be considered in the context of lower sensitivity and frequently reduced spatial resolution. The layered structure of cartilage is one example where a particularly strong variation of T₁ across the tissue occurs, being affected by degenerative diseases such as osteoarthritis (OA). Furthermore, the presence of ¹H‐¹⁴N cross‐relaxation, leading to so‐called quadrupolar dips in the ¹H relaxation time dispersion, provide insight into the concentration and mobility of proteoglycans and collagen in cartilage, both being affected by OA.

In this study, low‐field imaging and variable‐field NMR relaxometry were combined for the first time for tissue samples, employing unidirectional load to probe the mechanical properties. 20 human knee cartilage samples were placed in a compression cell, and studied by determining relaxation profiles without and with applied pressure (0.6 MPa) at 50 μm in‐plane resolution, and comparing with volume‐averaged T₁ dispersion. Samples were subsequently stored in formalin, prepared for histology and graded according to the Mankin score system.

Quadrupolar dips and thickness change under load showed the strongest correlation with Mankin grade. Average T₁ and change of maximum T₁ under load, as well as its position, correlate with thickness and thickness change. Furthermore, T₁(ω) above 25 mT was found to correlate with thickness change. While volume‐averaged T₁ is not a suitable indicator for OA, its change due to mechanical load and its extreme values are suggested as biomarkers available in low‐field MRI systems. The shape of the dispersion T₁(ω) represents a promising access to understanding and quantifying molecular dynamics in tissue, pointing toward future in vivo tissue studies.

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Series: NMR in biomedicine
ISSN: 0952-3480
ISSN-E: 1099-1492
ISSN-L: 0952-3480
Volume: 30
Issue: 8
Article number: e3738
DOI: 10.1002/nbm.3738
OADOI: https://oadoi.org/10.1002/nbm.3738
Type of Publication: A1 Journal article – refereed
Field of Science: 3126 Surgery, anesthesiology, intensive care, radiology
Subjects:
Funding: Part of this work was supported by the EU Horizon 2020 collaborative project IDentIFY (project number 668119). ER gratefully acknowledges CarlZeiss Stiftung for the scholarship to pursue his PhD research. MTN is indebted to Jane and Aatos Erkko Foundation, Finlandforfinancialsupport.
Copyright information: © 2017 John Wiley & Sons, Ltd. This is the peer reviewed version of the following article: Rössler, E, Mattea, C, Saarakkala, S, et al. Correlations of low‐field NMR and variable‐field NMR parameters with osteoarthritis in human articular cartilage under load. NMR in Biomedicine. 2017; 30:e3738. https://doi.org/10.1002/nbm.3738, which has been published in final form at https://doi.org/10.1002/nbm.3738. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.