Keywords:
Musculoskeletal soft tissue, Ultrasound physics, Musculoskeletal system, Ultrasound, Elastography, Experimental investigations, Tissue characterisation
Authors:
R. A. M. Santos1, P. Armada-da-Silva2; 1Coimbra/PT, 2Lisbon/PT
DOI:
10.1594/ecr2018/C-2378
Methods and materials
Sixteen young and active subjects,
ten males,
(mean ± SD; height: 1.69 ± 0.07 m,
weight: 66.7 ± 8.1 kg,
age: 20.06 ± 2.02 years) participated in this study.
Data were collected in a single session.
All contractions were performed on an isokinetic dynamometer (Biodex System 3,
Biodex Medical Systems).
After a warm-up,
participants performed a series of maximal contractions with the knee extensors,
followed by 2 sets of maximal Conc and Ecc contractions at diferent angular velocities and performed through a ROM between 90° and 0° of knee flexion.
After 5 min of resting,
two isometric ramp contractions were performed between 0 and 60% of isometric MVC and at 60° of knee flexion.
An Aixplorer US equipment (version 4.2; Supersonic Imagine,
Aix-en-Provence,
France) equipped with a 4-15 MHz linear transducer array (SuperLinear 15-4,
Vermon,
Tours,
France) in shear wave elastography mode and musculoskeletal preset was used for SSI muscle scanning.
The US probe was placed over the VL at a position corresponding to 39% of the distance between the upper edge of the patella and the anterior superior iliac spine (5).
B-mode images were used on longitudinal view.
Measurements of shear wave modulus were made with the knee at 10,
50,
and 90° flexion.
The shear wave elastography field of view was delimited by a fixed-size square ROI (1.5 cm2) placed within the VL and away from fibrous and adipose septa.
For each measurement,
the acquisition was made as a video of shear wave elastography maps (mp4 format) that were next transformed into a sequence of ‘jpeg’ images.
Using a Matlab routine (R2013a,
The MathWorks Inc.,
Natick,
USA).
The intensity of the pixels was quantified and converted to kPa values,
considering that the highest pixel values were red and the lowest blue.
The saturating shear modulus was above 100 kPa.