In this study, the performances of one-dimensional and two-dimensional
least-squares strain estimators (LSQSE) are compared. Furthermore, the effects
of kernel size are examined using simulated raw frequency data of a
widely-adapted hard lesion/soft tissue model. The performances of both methods
are assessed in terms of root-mean-squared errors (RMSE), elastographic
signal-to-noise ratio (SNRc) and contrast-to-noise ratio
(CNRc). RMSE analysis revealed that the 2D LSQSE yields better
results for phased array data, especially for larger insonification angles.
Using a 2D LSQSE enabled the processing of unfiltered displacement data, in
particular for the lateral/horizontal strain components. The SNRc and
CNRc analysis showed an improvement in precision and almost no
loss in contrast using 2D LSQSE. However, the RMSE images for different kernel
sizes revealed that the optimal 2D kernel size depends on the region-of-interest
and showed that the LSQ kernel size should be limited to avoid loss in
resolution.
OphirJ,
CéspedesI, PonnekantiH, YazdiY, LiX.Elastography: a quantitative method for imaging the elasticity of
biological tissues,Ultrasonic Imaging13,111–134
(1991).
2.
OphirJ, AlamSK, GarraB, Elastography: ultrasonic estimation and imaging of the elastic
properties of tissues,Proc Inst Mech Eng [H]213,203–233
(1999).
3.
CéspedesEI, OphirJ, PonnekantiH, MakladN.Elastography: elasticity imaging using ultrasound with
application to muscle and breast in vivo.Ultrasonic Imaging17,73–88 (1993).
4.
GarraBS,
CéspedesEI, OphirJ, Elastography of breast lesions: Initial clinical
results.Radiology202,79–86(1997).
5.
KallelF, PriceRE, KonofagouEE, OphirJ.Elastographic imaging of the normal canine prostate in
vitro,Ultrasonic Imaging21,201–215
(1999).
6.
de KorteCL, PasterkampG, van der SteenAFW, WoutmanHA, BomN.Characterization of plaque components using intravascular
ultrasound elastography in human femoral and coronary arteries in
vitro,Circulation102,617–623
(2000).
7.
SchmittC, SoulezG, MauriceRL, GirouxMF, CloutierG.Noninvasive vascular elastography: toward a complementary
characterization tool of atherosclerosis in carotid
arteries.Ultrasound Med Biol33,1841–1858
(2007).
8.
D'hoogeJ, KonofagouE, JamalF, Two-dimensional ultrasonic strain rate measurement of the human
heart in vivo,IEEE Trans Ultrason Ferroel Freq Contr49,281–6 (2002).
9.
KonofagouEE,
D'hoogeJ, OphirJ.Myocardial elastography — a feasibility study in
vivo,Ultrasound Med Biol28,475–482
(2002).
10.
AlamSK, OphirJ, KonofagouEE.An adaptive strain estimator for elastography,IEEE Trans Ultrason Ferroel Freq Contr45,461–472
(1998).
11.
ElenA, ChoiHF, LoeckxD, Three-dimensional cardiac strain estimation using spatio-temporal
elastic registration of ultrasound images: a feasibility
study,IEEE Trans Medlmag27,1580–1591
(2008).
12.
SrinivasanS, OphirJ.A zero-crossing strain estimator for
elastography,Ultrasound Med Biol29,227–238
(2003).
13.
Zahiri-AzarR, SalcudeanSE.Time-delay estimation in ultrasound echo signals using individual
sample tracking,IEEE Trans Ultrason Ferroel Freq Contr55,2640–2650
(2008).
14.
KonofagouE, OphirJ.A new elastographic method for estimation and imaging of lateral
displacements, lateral strains, corrected axial strains and Poisson's
ratios in tissues,Ultrasound Med Biol24,1183–1199
(1998).
15.
LangelandS, D'hoogeJ, TorpH, BijnensB, SuetensP.Comparison of time-domain displacement estimators for
two-dimensional rf tracking,Ultrasound Med Biol29,1177–1186(2003).
16.
LopataRGP, NillesenMM, HansenHHG, Performance evaluation of methods for two-dimensional strain
estimation using ultrasound radio frequency data,Ultrasound Med Biol (in press,
2009).
17.
CéspedesI, OphirJ.Reduction of image noise in elastography,Ultrasonic Imaging15,89–102
(1993).
18.
KallelF, OphirJ.A least-squares strain estimator for
elastography,Ultrasonic Imaging19,195–208
(1997).
19.
VargheseT.OphirJ, CespedesI.Noise reduction in elastograms using temporal stretching with
multi-compression averaging,Ultrasound Med Biol22,1043–1052
(1996).
20.
LeeWN, KonofagouEE.Angle-independent and multi-dimensional myocardial
elastography—from theory to clinical validation.Ultrasonics48,563–567
(2008).
21.
LuoJ, BaiJ, HeP, YingK.Axial strain calculation using a low-pass digital differentiator
in ultrasound elastography,IEEE Trans Ultrason Ferroel Freq Conn51,1119–1127
(2004).
22.
SrinivasanS, KallelF, OphirJ.Estimating the elastographic signal-to-noise ratio using
correlation coefficients,Ultrasound Med Biol28,359–368
(2002).
23.
LubinskiMA, EmelianovSY, RaghavanKR, Lateral displacement estimation using tissue
incompressibility,IEEE Trans Ultrason Ferroel Freq Contr43,247–256
(1996).
24.
SumiC, SatoK.Regularization for ultrasonic measurements of tissue displacement
vector and strain tensor,IEEE Trans Ultrason Ferroel Freq Contr55,787–799
(2008).
25.
LangelandS, D'hoogeJ, WoutersPF, Experimental validation of a new ultrasound method for the
simultaneous assessment of radial and longitudinal myocardial deformation
independent of insonification angle,Circulation112,2157–2162(2005).
26.
LeeWN,
CmLngrassia,
Fung-Kee-FungSD, Theoretical quality assessment of myocardial elastography with in
vivo validation,IEEE Trans Ultrason Ferroel Freq Contr54,2233–2245
(2007).
27.
LopataRGP, NillesenMM, GerritsIH, In vivo 3D cardiac and skeletal muscle strain estimation,
inProc IEEE Ultrasonics Symp, pp.
744–747
(2006).
28.
LopataRGP, NillesenMM, GerritsIH, 4D cardiac strain imaging: methods and initial results,
inProc IEEE Ultrasonics Symp, pp.
872–875
(2007).
29.
AlamSK, OphirJ, VargheseT.Elastographic axial resolution criteria: An experimental
study,IEEE Trans Ultrason Ferroel Freq Contr47,304–309
(2000).
30.
RighettiR, OphirJ, KtonasP.Axial resolution in elastography,Ultrasound Med Biol28,101–113
(2002).
31.
JensenJA.Field: A program for simulating ultrasound
systems, in Medical & Biological Engineering
& Computing. pp. 351-353
(1996).
32.
KallelF, BertrandM, OphirJ.Fundamental limitations on the contrast-transfer efficiency in
elastography: an analytic study.Ultrasound Med Biol22,463–470
(1996).
33.
PonnekantiH, OphirJ, HuangY, CespedesI.Fundamental mechanical limitations on the visualization of
elasticity contrast in elastography,Ultrasound Med Biol21,533–543
(1995).
34.
OosterveldBJ, ThijssenJM, VerhoefWA.Texture of B-mode echograms: 3-D simulations and experiments of
the effects of diffraction and scatterer density,Ultrasonic Imaging7,142–160(1985).
35.
MadsenEL, FrankGR, HobsonMA, Spherical lesion phantoms for testing the performance of
elastography systems,Phys Med Biol50,5983–5995
(2005).
36.
de KorteCL,
CéspedesEI, van der SteenAFW, NorderB, te NijenhuisK.Elastic and acoustic properties of vessel mimicking material for
elasticity imaging,Ultrasonic Imaging19,112–126
(1997).
37.
LopataRGP, NillesenMM, HansenHHG, Performance of two-dimensional displacement and strain estimation
techniques using a phased array transducer,Ultrasound Med Biol (submitted).
38.
BilgenM, InsanaM.Predicting target detectability in acoustic
elastography, in Proc IEEE Ultrasonics
Symp, pp. 1427-1430
(1997).
39.
VargheseT, OphirJ.A theoretical framework for performance characterization of
elastography: the strain filter,IEEE Trans Ultrason Ferroel Freq Contr44,164–172
(1997).
