Elastography is an emerging imaging modality that allows noninvasive imaging of tissue stiffness changes and stiffness values associated with pathology or as a result of therapy. However, many currently-used systems for elastography rely on a fixed geometry transducer and compressor system for imaging. This configuration is disadvantageous for imaging difficult-to-reach regions that are currently accessible with conventional ultrasound. In this paper, we describe a handheld, portable stepper motor controlled system for elastography. This system may reduce motion and jitter errors that are prevalent in completely ‘freehand elastography’ that employs hand-induced compressions using the transducer. The latter also requires collection of large amounts of data and use of strain estimation algorithms that may not be sensitive to phase changes or use additional preprocessing to minimize decorrelation effects. The stepper motor controlled handheld system provides controlled compressions and synchronized data acquisition. Our technique yields elastograms of a low-contrast phantom that have contrast levels and contrast-to-noise ratios that are comparable to those obtained with a fixed geometry system.
OphirJCéspedesEIPonnekantiHYazdiYLiX, Elastography: a quantitative method for imaging the elasticity of biological tissues, Ultrasonic Imaging13, 111–134 (1991).
2.
OphirJCéspedesIGarraBSPonnekantiHHuangYMakladN, Elastography: ultrasonic imaging of tissue strain and elastic modulusin vivo, Euro. J. Ultrasound3, 49–70 (1996).
3.
OphirJKallelFVargheseTBertrandMCéspedesIPonnekantiH, Elastography: A systems approach, Int. J. Imag. Sys. Tech.8, 89–103 (1997).
4.
OphirJAlamKAGarraBSKallelFKonofagouEEKrouskopTAVargheseT, Elastography: ultrasonic estimation and imaging of the elastic properties of tissues, J. Eng. Med.213, 203–233 (1999).
5.
OphirJGarraBSKallelFKonofagouEEKrouskopTARighettiRVargheseT, Elastographic imaging, Ultrasound Med Biol.26, S23–S29 (2000).
6.
CéspedesEI, Elastography: Imaging of Biological Tissue Elasticity (Ph. D. Dissertation, University of Houston, 1993).
7.
GarraBSCéspedesEIOphirJSprattRSZuurbierRAMagnantCMPennanenMF, Elastography of breast lesions: initial clinical results, Radiology202, 79–86 (1997).
8.
O'DonnellMSkovorodaA. R.ShapoB. M., Measurement of arterial wall motion using Fourier based speckle-tracking algorithms, in Proc. IEEE Ultras. Symp. pp. 1101–1104 (1991).
9.
O'DonnellMSkovorodaARShapoBMEmelianovSY, Internal displacement and strain imaging using ultrasonic speckle tracking, IEEE Trans. Ultrason. Ferroel. Freq. Cont.41, 314–325 (1994).
10.
KrouskopTAVinsonSGoodeBDoughertyD, A pulsed Doppler ultrasonic system for making noninvasive measurements of the mechanical properties of soft tissue, J. Rehab. Res. and Dev.24, 1–8 (1987).
11.
YamakoshiYSatoJSatoT, Ultrasonic imaging of internal vibration of soft tissue under forced vibration, IEEE Trans. Ultrason. Ferroel. Freq. Cont.37, 45–53 (1990).
12.
ParkerKJHuangSRMusulinRALernerRM, Tissue response to mechanical vibrations for Sonoelasticity Imaging, Ultrasound Med. Biol.16, 241–246 (1990).
13.
LernerRMHuangSRParkerKJ, “Sonoelasticity” images derived from ultrasound signals in mechanically vibrated tissues, Ultrasound Med. Biol.16, 231–239 (1990).
14.
WilsonLSRobinsonDE, Ultrasonic measurement of small displacements and deformations of tissue, Ultrasonic Imaging4, 71–82 (1982).
15.
BertrandMMeunierMDoucetMFerlandG, Ultrasonic biomechanical strain gauge based on speckle tracking, in Proc. 1989 IEEE Ultrason. Symp., pp. 859–864, (1989).
16.
De KorteCLVan der SteenAFCespedesEIPasterkampG, Intravascular ultrasound elastography in human arteries: Initial experience in vitro, Ultrasound Med. Biol.24, 401–408 (1998).
17.
PesaventoALorenzASiebersSErmertH, New real-time strain imaging concepts using diagnostic ultrasound, Phys Med Biol.45, 1423–1435 (2000).
18.
VargheseTZagzebskiJAChenQFrankGTechavipooULeeFTJr., Noninvasive monitoring of temperature and lesion formation duringCTE ablation, Ultrasonic Imaging22, 245 (2000) (abstract).
19.
BamberCJBushLN, Freehand elasticity imaging using speckle decorrelation rate, in Acoust. Imaging22, TortoliPMasottiL, Eds., pp. 285–292 (1996).
20.
DoyleyMM, An Investigation into Methods for Improving the Clinical Usefulness of Elasticity Imaging, (Ph. D Dissertation, University of London, 1999).
21.
DoyleyMMBamberJCFuechselFBushNL, A freehand elastographic imaging approach for clinical breast imaging: system development and performance evaluation, Ultrasound Med Biol.27, 1347–57 (2001).
22.
HiltawskyKMKrügerMStarkeCHeuserLErmertHJensenA, Freehand ultrasound elastography of breast lesions: clinical results, Ultrasound Med Biol.27, 1461–1469 (2001).
23.
ZhuYHallTJ, A new system for real-time freehand imaging of tissue elasticity, RSNA692 (2001) (poster).
24.
VargheseTOphirJ, Estimating tissue strain from signal decorrelation using the correlation coefficient, Ultrasound Med. Biol.22, 1249–1254 (1996).
25.
VargheseTOphirJ, Characterization of elastographic noise using the envelope of echo signals, Ultrasound Med. Biol.24, 543–555 (1998).
26.
ChaCHLeeFTGurneyJMCT versus sonography for monitoring radiofrequency ablation in a porcine liver, Am J Roentgenol.175, 705–711 (2000).
27.
MadsenELFrankGR, US Patent Application P02103US (2002).
28.
KallelFOphirJ, A least squares estimator for elastography, Ultrasonic Imaging19, 195–208 (1997).
RighettiROphirJKtonasP, Axial resolution in elastography, Ultrasound Med Biol.28, 101–13 (2002).
31.
VargheseTOphirJ, An analysis of the elastographic contrast-to-noise ratio performance, Ultrasound Med. Biol.24, 915–924 (1998).
32.
MaloneDELesiukLBradyAPWymanDRWilsonBC, Hepatic interstitial laser photocoagulation: demonstration and possible clinical importance of intravascular gas. Radiology193, 233–237 (1994).
33.
GoldbergSNGazelleGSMuellerPR, Thermal ablation therapy for focal malignancy: a unified approach to underlying principles, techniques, and diagnostic imaging guidance, Am J Roentgenol.174, 323–331 (2000).
VargheseTKonofagouEEOphirJAlamSKBilgenM, Direct strain estimation in elastography using spectral cross-correlation, Ultrasound Med. Biol.26, 1529–1537 (2000).
36.
VargheseTOphirJ, A theoretical framework for performance characterization of elastography: the strain filter, IEEE Trans. Ultrason. Ferroel. Freq. Cont.44, 164–172 (1997).
