Trade-offs between the axial resolution and the signal-to-noise ratio in elastography

S. Srinivasan, R. Righetti, Jonathan Ophir

Research output: Contribution to journalArticle

77 Scopus citations

Abstract

Elastography involves tracking the ultrasonic A-mode signals before and after mechanical compression of tissue to form a computed image of the local strains undergone by various tissue components. The quality of the strain estimates in elastography is typically quantified using factors such as the elastographic SNR (SNRe), contrast-to-noise ratio (CNRe), and the spatial resolution. These quality factors depend on the mechanical parameters (such as the applied strain and the boundary conditions), the acoustic parameters (such as the sonographic SNR, the center frequency, and the bandwidth), and the signal-processing parameters (such as the window length and the window separation). Theoretical developments in elastography have established functional relationships between the SNRe and CNRe and these parameters. Similarly, simulations have established empirical relationships between the axial resolution and the acoustic and signal-processing parameters. We find that a trade-off exists between the achievable SNRe (CNRe) and the axial resolution in elastography and that the trade-off occurs only with respect to the signal-processing parameters. Theoretical work on the spatial resolution accompanied with simulations and experiments were used to confirm such an observation. The trade-off between the SNRe (CNRe) and the resolution was found to be nonlinear, with large improvements in the SNRe being possible at the expense of small reductions in the axial resolution. All the quality factors improve with the acoustic parameters, which suggests the preferred use of transducers with high absolute bandwidths and center frequencies.

Original languageEnglish (US)
Pages (from-to)847-866
Number of pages20
JournalUltrasound in Medicine and Biology
Volume29
Issue number6
DOIs
StatePublished - Jun 1 2003

Keywords

  • Axial resolution
  • Band width
  • CNR
  • Correlation coefficient
  • Elastography
  • Lateral resolution
  • Resolution
  • SNR
  • Trade-off
  • Ultrasound
  • Window length
  • Window shift

ASJC Scopus subject areas

  • Biophysics
  • Radiological and Ultrasound Technology
  • Acoustics and Ultrasonics

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