Ultrashort echo time T2∗ values decrease in tendons with application of static tensile loads

Saeed Jerban,Amin Nazaran,Xin Cheng,Michael Carl,Nikolaus Szeverenyi,Jiang Du,Eric Y Chang

doi:10.1016/j.jbiomech.2017.07.018

Saeed Jerban, Amin Nazaran + Show 5 more

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https://doi.org/10.1016/j.jbiomech.2017.07.018

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Abstract

In early stages of tendon disease, mechanical properties may become altered prior to changes in morphological anatomy. Ultrashort echo time (UTE) magnetic resonance imaging (MRI) can be used to directly detect signal from tissues with very short T2 values, including unique viscoelastic tissues such as tendons. The purpose of this study was to use UTE sequences to measure T2∗, T1 and magnetization transfer ratio (MTR) variations of tendon samples under static tensile loads. Six human peroneal tendons were imaged before and under static loading using UTE sequences on a clinical 3T MRI scanner. Tendons were divided into two static tensile loading groups: group A that underwent one-step loading (15N) and group B that underwent two-step loading (15 and 30N). The T2∗, T1 and MTR variations were investigated in two selected section regions of interest (ROIs), including whole and core sections. Mean T2∗ values for the first step of loading (groups A and B) in both whole section and core section ROIs were significantly decreased by 13±7% (P=0.028) and 16±5% (P=0.017), respectively. For the second loading step (group B), there was a consistent, but non-significant reduction in T2∗ value by 9±2% (P=0.059) and 7±5% (P=0.121) for whole and core sections, respectively. Mean T1 did not show any consistent changes for either loading steps (P>0.05). Mean MTR increased slightly, but not significantly for both loading steps (P>0.05). Significant differences were found only in T2∗ values of tendons by static tensile load application. Therefore, T2∗ monitoring during loading is suggested for quantitative investigation of the tendons biomechanics.

Highlights

Tendons are unique viscoelastic connective tissues that are responsible for transferring the mechanical loads generated by muscles to the bones (Aparecida de Aro et al, 2012; Franchi et al, 2007b)
The calculated T2⁄ values showed a decrease for both the whole and the core sections after application of the first loading step (15 N), Fig. 1. (a) magnetic resonance imaging (MRI) compatible, plastic, loading device used for applying static extension loads on peroneal tendons soaked in fomblin. (b) Mounted tendon on the fixed and sliding grippers, using plastic bolts
This study investigates the mechanical status of tendons through observations in Ultrashort echo time (UTE)-MRI biomarkers

Summary

Introduction

Tendons are unique viscoelastic connective tissues that are responsible for transferring the mechanical loads generated by muscles to the bones (Aparecida de Aro et al, 2012; Franchi et al, 2007b). As the main viscous component (Wellen et al, 2005) of tissues, may comprise over 60% of the total tendon weight (Aparecida de Aro et al, 2012)). Of the dry weight of the tendon, 60–85% is composed of highly organized collagenous fibers, collagen type I (Aparecida de Aro et al, 2012). Collagenous fibers count for the elastic component of tendons (Wellen et al, 2005). The mechanical properties and great strength of tendons can be partially explained by their highly organized and hierarchical structure, which consist of collagen fibrils, fibers, bun-. Tendons demonstrate crimp or zigzag patterns in their microstructure that enable them to withstand, up to 3% strain without damage (Aparecida de Aro et al, 2012; Hansen et al, 2002; Khan et al, 1999)

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