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T1- and T2*-Mapping for Assessment of Tendon Tissue Biophysical Properties: A Phantom MRI Study


Bachmann, Elias; Rosskopf, Andrea B; Götschi, Tobias; Klarhöfer, Markus; Deligianni, Xeni; Hilbe, Monika; Pfirrmann, Christian W A; Snedeker, Jess Gerrit; Fischer, Michael A (2019). T1- and T2*-Mapping for Assessment of Tendon Tissue Biophysical Properties: A Phantom MRI Study. Investigative Radiology, 54(4):212-220.

Abstract

OBJECTIVES The aim of this study was to quantitatively assess changes in collagen structure using MR T1- and T2*-mapping in a novel controlled ex vivo tendon model setup. MATERIALS AND METHODS Twenty-four cadaveric bovine flexor tendons underwent MRI at 3 T before and after chemical modifications, representing mechanical degeneration and augmentation. Collagen degradation (COL), augmenting collagen fiber cross-linking (CXL), and a control (phosphate-buffered saline [PBS]) were examined in experimental groups, using histopathology as standard of reference. Variable echo-time and variable-flip angle gradient-echo sequences were used for T2*- and T1-mapping, respectively. Standard T1- and T2-weighted spin-echo sequences were acquired for visual assessment of tendon texture. Tendons were assessed subsequently for their biomechanical properties and compared with quantitative MRI analysis. RESULTS T1- and T2*-mapping was feasible and repeatable for untreated (mean, 545 milliseconds, 2.0 milliseconds) and treated tendons. Mean T1 and T2* values of COL, CXL, and PBS tendons were 1459, 934, and 1017 milliseconds, and 5.5, 3.6, and 2.5 milliseconds, respectively. T2* values were significantly different between enzymatically degraded tendons, cross-linked tendons, and controls, and were significantly correlated with mechanical tendon properties (r = -0.74, P < 0.01). T1 values and visual assessment could not differentiate CXL from PBS tendons. Photo-spectroscopy showed increased autofluorescence of cross-linked tendons, whereas histopathology verified degenerative lesions of enzymatically degraded tendons. CONCLUSIONS T2*-mapping has the potential to detect and quantify subtle changes in tendon collagen structure not visible on conventional clinical MRI. Tendon T2* values might serve as a biomarker for biochemical alterations associated with tendon pathology.

Abstract

OBJECTIVES The aim of this study was to quantitatively assess changes in collagen structure using MR T1- and T2*-mapping in a novel controlled ex vivo tendon model setup. MATERIALS AND METHODS Twenty-four cadaveric bovine flexor tendons underwent MRI at 3 T before and after chemical modifications, representing mechanical degeneration and augmentation. Collagen degradation (COL), augmenting collagen fiber cross-linking (CXL), and a control (phosphate-buffered saline [PBS]) were examined in experimental groups, using histopathology as standard of reference. Variable echo-time and variable-flip angle gradient-echo sequences were used for T2*- and T1-mapping, respectively. Standard T1- and T2-weighted spin-echo sequences were acquired for visual assessment of tendon texture. Tendons were assessed subsequently for their biomechanical properties and compared with quantitative MRI analysis. RESULTS T1- and T2*-mapping was feasible and repeatable for untreated (mean, 545 milliseconds, 2.0 milliseconds) and treated tendons. Mean T1 and T2* values of COL, CXL, and PBS tendons were 1459, 934, and 1017 milliseconds, and 5.5, 3.6, and 2.5 milliseconds, respectively. T2* values were significantly different between enzymatically degraded tendons, cross-linked tendons, and controls, and were significantly correlated with mechanical tendon properties (r = -0.74, P < 0.01). T1 values and visual assessment could not differentiate CXL from PBS tendons. Photo-spectroscopy showed increased autofluorescence of cross-linked tendons, whereas histopathology verified degenerative lesions of enzymatically degraded tendons. CONCLUSIONS T2*-mapping has the potential to detect and quantify subtle changes in tendon collagen structure not visible on conventional clinical MRI. Tendon T2* values might serve as a biomarker for biochemical alterations associated with tendon pathology.

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Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Balgrist University Hospital, Swiss Spinal Cord Injury Center
05 Vetsuisse Faculty > Institute of Veterinary Pathology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:1 April 2019
Deposited On:30 Nov 2018 13:38
Last Modified:16 Nov 2019 01:00
Publisher:Lippincott Williams & Wilkins
ISSN:0020-9996
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1097/RLI.0000000000000532
PubMed ID:30444794

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