University of Oulu

Hänninen, N.E., Liimatainen, T., Hanni, M. et al. Relaxation anisotropy of quantitative MRI parameters in biological tissues. Sci Rep 12, 12155 (2022).

Relaxation anisotropy of quantitative MRI parameters in biological tissues

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Author: Hänninen, Nina Elina1,2; Liimatainen, Timo1,3; Hanni, Matti1,3,4;
Organizations: 1Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland
2Department of Applied Physics, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland
3Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
4Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
5A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 11.1 MB)
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Language: English
Published: Springer Nature, 2022
Publish Date: 2022-10-07


Quantitative MR relaxation parameters vary in the 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 each tissue type 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, continuous wave (CW‐) T1ρ, adiabatic T1ρ and T2ρ, and Relaxation along fictitious field (RAFF2‐4) sequences at five different orientations with respect to the main magnetic field. Relaxation anisotropy of the measured parameters was quantified and compared. The highly ordered collagenous tissues, i.e. 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. T1 and adiabatic T1ρ did not exhibit observable anisotropy. In the other measured tissue types, anisotropy was overall less than 10% for all the parameters. The results confirm that highly ordered collagenous tissues have properties that induce very clearly observable relaxation anisotropy, whereas in other tissues the effect is not as prominent. Quantitative comparison of anisotropy of different relaxation parameters highlights the importance of sequence choice and design in MR imaging.

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Series: Scientific reports
ISSN: 2045-2322
ISSN-E: 2045-2322
ISSN-L: 2045-2322
Volume: 12
Article number: 12155
DOI: 10.1038/s41598-022-15773-8
Type of Publication: A1 Journal article – refereed
Field of Science: 3126 Surgery, anesthesiology, intensive care, radiology
Funding: Financial support from the Academy of Finland (grants #285909, #293970, #297033, #319440, #325146 and #340761) and the Finnish Cultural Foundation are gratefully acknowledged.
Academy of Finland Grant Number: 285909
Detailed Information: 285909 (Academy of Finland Funding decision)
293970 (Academy of Finland Funding decision)
297033 (Academy of Finland Funding decision)
319440 (Academy of Finland Funding decision)
325146 (Academy of Finland Funding decision)
340761 (Academy of Finland Funding decision)
Dataset Reference: The datasets used and analysed during the current study are available for download at Zenodo:
Copyright information: © The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.