User Guide
13
ELASTICITY CONTRAST SENSITIVITY
The Model 040GSE provides elasticity targets for the next generation of ultrasound
imagers using elastography. The elasticity value for the background is 20 kPa.
The target group at a depth of 1.5 cm has a diameter of 6mm, while the target
group at 5 cm has a diameter of 8 mm. Both groups provide elasticity values of 10,
50 and 100 kPa.
These targets are suitable for qualitative assessment of sonoelastography systems,
and checking system performance over time. Elasticity contrast is assessed as
follows:
1. Apply coupling gel to the scanning surface or ll the water trough with tap
water.
2. Position the transducer above the elasticity targets and perpendicular to the
wires.
3. In sonoelastography mode adjust the instrument settings.
4. Change settings to acquire optimal images.
5. Observe the general appearance of each tumor. Note how well you are able to
see each of the masses. Quantitative measurements based on the
elastography color scale, or the shear wave speed reading, may be used for
tracking the consistency of elastography measurements over time.
6. Record your observations.
Note: Due to the limited spatial resolution of some shear wave elastography
systems, the modulus readings of the elastography targets may get averaged with
the modulus of the background. In this case, you may want to test your readings
against the 040GSE background (nominal modulus of 20 kPa) or obtain the Model
039 Shear Wave Elastography set.
The modulus readings provided are tested using a stress/strain compression stand
based on ASTM standard D575-91, and your readings may differ slightly due to dif-
ferences in test methodology. For more information, refer to the following reference:
Oudry J, Lynch T, Vappou J, Sandrin L, Miette V. “Comparison of four different techniques to evaluate the elastic properties of
phantom in elastography: is there a gold standard?” Phys Med Biol. 2014 Oct 7;59(19):5775-93.
DEAD ZONE ASSESSMENT
The near eld group is used to assess the distance from the front face of the
transducer to the closest identiable echo. This region, where no useful information
is obtained, is commonly referred to as the “dead-zone,” “ring-down distance,” or
"near eld resolution." The dead zone occurs because the ultrasound system can-
not send and receive data simultaneously. It is instrument dependent and is dimin-
ished as frequency is increased. A change in your system’s dead zone is indicative
of a problem with the transducer, the pulsing system or both.