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Contrast Biases The Autocorrelation Phase Shift Estimation In Doppler Tissue Imaging

Författare:
  • Marcus Ressner
  • Tomas Jansson
  • Jonny Cedefamn
  • Per Ask
  • Birgitta Janerot-Sjoberg
Publiceringsår: 2009
Språk: Engelska
Sidor: 447-457
Publikation/Tidskrift/Serie: Ultrasound In Medicine And Biology
Volym: 35
Nummer: 3
Dokumenttyp: Artikel
Förlag: Elsevier

Sammanfattning

Quantitative assessment of regional myocardial function at rest and during stress with Doppler tissue imaging (DTI) plays an important role in daily routine echocardiography. However, reliable visual analysis is largely dependent on image quality and adequate border delineation, which still remains a challenge in a significant number of patients. In this respect, an ultrasound contrast agent (UCA) is often used to improve visualization in patients with suboptimal image quality. The knowledge of how DTI measurements will be affected by UCA present in the tissue is therefore of significant importance for an accurate interpretation of local myocardial motion. The aim of this paper was to investigate how signal contribution from UCA and nonlinear wave propagation influence the performance of the autocorrelation phase shift estimator used for DTI applications. Our results are based on model experiments with a clinical 2-D grayscale scanner and computational simulations or the DTI velocity estimator for synthetically-derived pulses, simulated bubble echoes and experimentally-sampled RF data of transmitted pulses and backscattered contrast echoes. The results show that destruction of UCA present in the tissue will give rise to an apparent bidirectional velocity bias of individual velocity estimates, but that spatial averaging of individual velocity measurements within a region-of-interest will result in a negative bias (away from the transducer) of the estimated mean or mean peak velocity. The UCA destruction will also have a significant impact on the measured integrated mean velocity over time, i.e., displacement. To achieve improved visualization with UCA during DTI-examinations, we either recommend that it is performed at low acoustic powers, mechanical index <= 0.3, thereby minimizing the effects from bubble rupture, or that each Doppler pulse package is preceded by a destruction burst similar to "Flash imaging" to clear the target area of contrast microbubbles. (E-mail: marcus [dot] ressner [at] imt [dot] liu [dot] se) (C) 2009 World Federation for Ultrasound in Medicine & Biology.

Disputation

Nyckelord

  • Technology and Engineering
  • Contrast
  • Ultrasound
  • Tissue Doppler
  • Microbubbles
  • Velocity estimation

Övriga

Published
Yes
  • ISSN: 0301-5629

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