Ultrasound Tissue Characterization of Human Achilles Tendon by Stability Quantification of Echo Patterns

Summary

Ultrasound is the approach most commonly adopted in the clinical setting for the assessment of the size and structure of the Achilles tendon. To expand the Achilles tendon assessment in a more comprehensive manner, the ultrasound tissue characterization (UTC) approach has recently been proposed and validated in clinical studies.

Abstract

The assessment of tendon size and structure is commonly included in the clinical management of healthy athletes and different types of patients to personalize their training or rehabilitation. The quantitative analysis of the Achilles tendon structure described here can be performed with a recently introduced system that is non-invasive, relatively inexpensive, portable, radiation-free, and enables the rapid collection of accurate and reproducible data. It uses a standard ultrasound probe that is automatically displaced by a tracker in precise steps of 0.2 mm across the region of interest to collect successive two-dimensional ultrasound images that are then compiled into three-dimensional data-block. The measurement procedure is simple: a subject can be tested in 10-15 min, and a comprehensive report is automatically generated. The quantification of four different echo types enables the evaluation of the tissue integrity: this quantification can be useful for the diagnostic and prognostic assessment of patients with Achilles tendinopathy.

Introduction

The Achilles tendon is a common site of tendinopathy, causing pain, physical impairment, and disability^1,2. Achilles tendinopathy is a common disorder arising from overuse, especially among athletes, but it is also prevalent in sedentary people and patients with rheumatologic and endocrine diseases³. Two distinct forms of Achilles tendinopathy can be diagnosed: midportion tendinopathy that affects the tendon 2-7 cm above its calcaneal insertion and insertional tendinopathy that involves the distal 2 cm of tendon proximal to the calcaneus⁴. Midportion Achilles ten....

Protocol

The protocol follows the research integrity guidelines of the Polytechnic of Turin²⁸. The acquisition of ultrasound images was performed within a research study approved by the local ethics committee ("Comitato Etico Interaziendale": protocol n. 0001612/30/12/2021), and the investigated subjects gave their written consent (for study participation and publication of anonymized images).

1. System preparation

NOTE: The system is made of four components (see Table of Materials): Smart System with the ultrasound scanner software; analysis software; multi-frequency (5-16 MHz) 192-....

Results

Figure 1 shows representative images of a normal Achilles tendon. The qualitative assessment of tendon structure (in both longitudinal and transversal scans) showed a homogeneous echogenicity and the quantitative assessment of tendon size (the target for the thickness measurement was taken at position #2 that corresponded to the thickest part of the tendon in the transversal view) documented a normal thickness (4 mm).

The UTC analysis reported a normal structure o.......

Discussion

The procedure presented in this article can be used to evaluate size and structure of the Achilles tendon through a commercially available solution that has been previously developed^13,14 and validated in both healthy and pathological tendons^{14,15,16,17,18}. This solution offers several advantages: it i.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
5 – 16 MHz Linear Array Probe	Terason	16L5	"Transducer" in the manuscript
uSmart 3200T ultrasound scanner	Terason	Terason TAB3	"Smart system" in the manuscript
UTC Software	UTC Imaging	Version 1.0.0	"Analysis software" in the manuscript
UTC Tracker	UTC Imaging		"Tracker" in the manuscript