Ultrasound and magnetic resonance imaging are not interchangeable to assess the Achilles tendon cross-sectional-area

Annika Kruse,Markus Tilp,Savvas Stafilidis

doi:10.1007/s00421-016-3500-1

Annika Kruse, Markus Tilp + Show 1 more

Open Access

https://doi.org/10.1007/s00421-016-3500-1

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Abstract

PurposeThe major aim of this study was to compare ultrasound (US) and magnetic resonance imaging (MRI) measurements of the Achilles tendon cross-sectional area (CSA). Further aims were to conduct reliability analyses and to assess the influence of transducer pressure on the tendon properties in US measurements.MethodsThe Achilles tendon CSA of 15 participants was assessed at two positions with US and MRI by use of a standardized protocol. Method comparison was performed by two-way analysis of variance (ANOVA) and paired t test. Reliability was assessed by coefficients of variation (CV), intraclass correlation (ICC2,2), standard error of measurement (SEM), and minimal detectable change (MDC95). A paired t test was performed to investigate the effect of probe pressure on tendon CSA and thickness.ResultsMean US measurements provided a ~5.5% smaller CSA compared to MRI measurements. Intra-rater reliability analyses of US demonstrated CV values of 1.5–4.9%, ICC of 0.89–0.97, SEM and MDC95 values of 0.22–0.77 mm2 and 0.61–2.16 mm2 for both raters, whereby CV values for intra-rater reliability of MRI ranged from 1.0 to 3.7%. Inter-rater reliability was lower for both modalities. Pressure applied on the transducer altered Achilles tendon CSA and thickness significantly (p < 0.05).ConclusionsOur findings show that US and MRI cannot be used interchangeably for Achilles tendon CSA assessments, however, each imaging modality separately is reliable to assess this property. Pressure applied on the transducer during US measurements causes alterations of the tendon’s morphology and should be avoided.

Highlights

Ultrasound (US) and magnetic resonance imaging (MRI) are the most frequently used imaging methods to assess the cross-sectional area (CSA) of tendons (Pierre-Jerome et al 2010)
Our findings show that US and MRI cannot be used interchangeably for Achilles tendon CSA assessments, each imaging modality separately is reliable to assess this property
The US method used for image analysis underestimated the CSA by ~4.6% and ~6.3% for the distal and proximal position, respectively

Summary

Introduction

Ultrasound (US) and magnetic resonance imaging (MRI) are the most frequently used imaging methods to assess the cross-sectional area (CSA) of tendons (Pierre-Jerome et al 2010). (Skou and Aalkjaer 2013) when the morphological and mechanical properties of tissue are assessed, e.g., to investigate intervention-related alterations In this context, several studies examined the reliability of either US (Brushoj et al 2006; Dudley-Javoroski et al 2010; Foure et al 2011; Intziegianni et al 2015; Kubo et al 2014; Milgrom et al 2014; Ying et al 2003) or MRI (Arampatzis et al 2010; Brushoj et al 2006; Hansen et al 2003; Kubo et al 2002; Magnusson et al 2001) measurements of the AT CSA and demonstrated predominantly good to excellent reliability for US applications. Referring to the aforementioned considerations, the application of US for the investigation of the AT CSA should be justified by its comparability or interchangeability with the well-established imaging method MRI (Jacobson 2005; Rasmusson 2000)

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