Ultrasonic strain elastography for detecting abnormalities in the supraspinatus tendon: an intra- and inter-rater reliability study

Abstract

ObjectivesThe reliability of ultrasonic strain elastography (SEL) used to detect abnormalities in the supraspinatus tendon is unclear. Thus, the aim of this study was to investigate the reliability of SEL in the supraspinatus tendon.DesignAn intra-rater and inter-rater reliability study.SettingA single-centre study conducted at the University of Southern Denmark.ParticipantsTwenty participants with shoulder pain and MRI-verified supraspinatus tendinosis and 20 asymptomatic participants (no MRI).Primary and secondary outcome measuresRaw values (RAW) and ratios (deltoid muscle (DELT) and gel pad (GEL) as reference tissues) were calculated and mean values of measurements from three regions of the supraspinatus tendon were reported. Colour scale ratings and number of yellow/red lesions from the three areas were also included.ResultsIntra-rater reliability showed intraclass correlation coefficients (ICCs) for RAW, DELT and GEL: 0.97 (minimal detectable change (MDC): 0.28 (6.36% of the mean)), 0.89 (MDC: 2.91 (20.37%)) and 0.73 (MDC: 1.61 (58.82%)), respectively. The ICCs for inter-rater reliability were 0.89 (MDC: 0.47 (10.53%)), 0.78 (MDC: 3.69 (25.51%)) and 0.70 (MDC: 1.75 (62.63%)), respectively.For colour scale ratings, intra-rater reliability (linear weighted kappa) ranged from 0.76 to 0.79, with the inter-rater reliability from 0.71 to 0.81. For the number of lesions, intra-rater reliability ranged from 0.40 to 0.82 and inter-rater reliability from 0.24 to 0.67.ConclusionsIntra-rater and inter-rater reliability were excellent for raw values and for ratios with deltoid muscle as the reference tissue, and good for ratios with gel pad as the reference tissue. The reliability of colour scale ratings was substantial-to-almost perfect, and for the number of lesions fair-to-almost perfect.Although high reliability was found, validity and responsiveness of these elastographic methods needs further investigation.Ethics approvalThe study protocol was approved by the Ethics Committee for the Region of South Denmark (S-20160115) and reported to the Danish Data Protection Agency (2014-41-3266).

Strain Elastography and Tendon Response to an Exercise Program in Patients With Supraspinatus Tendinopathy: An Exploratory Study

“…The supraspinatus tendons were scanned bilaterally while the patient was sitting in a custom-made chair ensuring the upper limb was held in a standardized position (at both baseline and follow-up), with the hand placed on the backrest, as previously described. 4 …”

“…Where no such tendon changes were identified using conventional US, SEL was captured in a standardized position, with the probe placed laterally from the anterior-lateral corner of the acromion as previously described. 4 Image window depth and width and the tissue compression force technique were performed according to previous recommendations. 8 , 12 Only high-quality images, determined by an in-built software quality bar, were used for analysis, as recommended by the manufacturer (GE Healthcare, personal communication with application specialist in Ultrasound, Heidi Sørensen, 2018).…”

“…These included the raw strain index (RAW; continuous scale from 0 = softest tendon to 6 = stiffest tendon) and a ratio between the selected tendon area and a soft part of the deltoid muscle (DELT), calculated as the strain value of the supraspinatus tendon divided by the DELT value, as previously described. 4 The SEL was performed and assessed by a radiographer (K.B.) with 4 years of experience in musculoskeletal SEL.…”

“…It has been recommended to present ratios between the region of interest and a reference area because the applied stress in SEL cannot directly be measured. 9 , 12 SEL has shown satisfactory reliability 4 and validity in patients with supraspinatus tendinopathy and healthy volunteers. 3 , 23 Follow-up evaluation of tissue elasticity using sonoelastography has, to our knowledge, only been estimated in 2 studies, both of which involved only the Achilles tendon.…”

Clinimetric properties of Strain Elastography in patients with supraspinatus tendinopathy

“…Acceptable intra-rater and inter-rater reliability were found using either of the SEL methods. However, the RAW variable had the highest reliability, and the measurement error from GEL exceeded the difference between healthy participants and patients [7].…”