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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Comparison of Pushing Sequences for Shear Wave Elastography / Jämförelse av trycksekvenser för skjuvningsvågelastografi

Nordenfur, Tim January 2013 (has links)
Shear wave elastography is a medical imaging modality in which tissue elasticity is estimated by measuring the speed of ultrasound-induced shear waves. This study aimed to implement four shear wave generating pushes and compare their performance according to chosen metrics. The focused push, unfocused push, unfocused comb push and line push were implemented on a Verasonics ultrasound system and tested on a polyvinyl alcohol phantom. Shear wave propagation was imaged using angle-compounded ultrafast imaging. Axial particle velocities were estimated using a 2D autocorrelator and then cross-correlated to obtain local shear wave speed estimates. The focused push and line push were found to generate shear waves with 1--3 times higher peak axial particle velocity, implying better signal-to-noise ratios. The focused push, unfocused push and line push were found to exhibit areas 7 mm wide around the pushing beams in which shear wave speed cannot be estimated, whereas the unfocused comb push has no such blind area.

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