Ultrasonic mapping of the microvasculature: Signal alignment

B. G. Zagar, R. J. Fornaris, K. W. Ferrara

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

The ultimate goal of this work was the development of a system capable of estimating the low flow velocities in the microvasculature. Estimation of low velocity flow within these vessels is challenging due to the small signal levels and the effect of cardiac and respiratory motion. Realignment of the signal from a single line-of-sight to remove physiological tissue motion is a critical part of the process of small-vessel flow mapping, and our methods for this alignment are considered in this paper. Each method involves the correlation of pulses acquired from the same line-of-sight. The first method involves the correlation of adjacent pulses (nearest-neighbor), the second involves a single reference line and the third involves averaging the correlation over a set of reference lines. We find that a nearest-neighbor strategy is suboptimal, and that strategies involving a global reference line are superior. A bound on the variance of estimates of the location of the correlation peak is presented. This bound allows us to consider our results in comparison with an absolute limit. Finally, a new algorithm allowing for alignment between lines-of-sight is described, and initial results are presented. Such an algorithm does, in fact, reduce jitter, correct for tissue motion and enables us to better visualize vessel continuity. We find that vessels as small as 40 μm can be mapped in two dimensions using a 50-MHz transducer.

Original languageEnglish (US)
Pages (from-to)809-824
Number of pages16
JournalUltrasound in Medicine and Biology
Volume24
Issue number6
DOIs
StatePublished - 1998
Externally publishedYes

Fingerprint

Microvessels
Ultrasonics
vessels
ultrasonics
alignment
line of sight
low speed
Transducers
pulses
continuity
transducers
estimating
flow velocity
vibration
estimates

Keywords

  • Blood flow mapping
  • Cross-correlation
  • Signal alignment
  • Velocity estimation

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

Cite this

Ultrasonic mapping of the microvasculature : Signal alignment. / Zagar, B. G.; Fornaris, R. J.; Ferrara, K. W.

In: Ultrasound in Medicine and Biology, Vol. 24, No. 6, 1998, p. 809-824.

Research output: Contribution to journalArticle

Zagar, B. G. ; Fornaris, R. J. ; Ferrara, K. W. / Ultrasonic mapping of the microvasculature : Signal alignment. In: Ultrasound in Medicine and Biology. 1998 ; Vol. 24, No. 6. pp. 809-824.
@article{220b4ecaac8346a289d0c061633ef95b,
title = "Ultrasonic mapping of the microvasculature: Signal alignment",
abstract = "The ultimate goal of this work was the development of a system capable of estimating the low flow velocities in the microvasculature. Estimation of low velocity flow within these vessels is challenging due to the small signal levels and the effect of cardiac and respiratory motion. Realignment of the signal from a single line-of-sight to remove physiological tissue motion is a critical part of the process of small-vessel flow mapping, and our methods for this alignment are considered in this paper. Each method involves the correlation of pulses acquired from the same line-of-sight. The first method involves the correlation of adjacent pulses (nearest-neighbor), the second involves a single reference line and the third involves averaging the correlation over a set of reference lines. We find that a nearest-neighbor strategy is suboptimal, and that strategies involving a global reference line are superior. A bound on the variance of estimates of the location of the correlation peak is presented. This bound allows us to consider our results in comparison with an absolute limit. Finally, a new algorithm allowing for alignment between lines-of-sight is described, and initial results are presented. Such an algorithm does, in fact, reduce jitter, correct for tissue motion and enables us to better visualize vessel continuity. We find that vessels as small as 40 μm can be mapped in two dimensions using a 50-MHz transducer.",
keywords = "Blood flow mapping, Cross-correlation, Signal alignment, Velocity estimation",
author = "Zagar, {B. G.} and Fornaris, {R. J.} and Ferrara, {K. W.}",
year = "1998",
doi = "10.1016/S0301-5629(98)00042-8",
language = "English (US)",
volume = "24",
pages = "809--824",
journal = "Ultrasound in Medicine and Biology",
issn = "0301-5629",
publisher = "Elsevier USA",
number = "6",

}

TY - JOUR

T1 - Ultrasonic mapping of the microvasculature

T2 - Signal alignment

AU - Zagar, B. G.

AU - Fornaris, R. J.

AU - Ferrara, K. W.

PY - 1998

Y1 - 1998

N2 - The ultimate goal of this work was the development of a system capable of estimating the low flow velocities in the microvasculature. Estimation of low velocity flow within these vessels is challenging due to the small signal levels and the effect of cardiac and respiratory motion. Realignment of the signal from a single line-of-sight to remove physiological tissue motion is a critical part of the process of small-vessel flow mapping, and our methods for this alignment are considered in this paper. Each method involves the correlation of pulses acquired from the same line-of-sight. The first method involves the correlation of adjacent pulses (nearest-neighbor), the second involves a single reference line and the third involves averaging the correlation over a set of reference lines. We find that a nearest-neighbor strategy is suboptimal, and that strategies involving a global reference line are superior. A bound on the variance of estimates of the location of the correlation peak is presented. This bound allows us to consider our results in comparison with an absolute limit. Finally, a new algorithm allowing for alignment between lines-of-sight is described, and initial results are presented. Such an algorithm does, in fact, reduce jitter, correct for tissue motion and enables us to better visualize vessel continuity. We find that vessels as small as 40 μm can be mapped in two dimensions using a 50-MHz transducer.

AB - The ultimate goal of this work was the development of a system capable of estimating the low flow velocities in the microvasculature. Estimation of low velocity flow within these vessels is challenging due to the small signal levels and the effect of cardiac and respiratory motion. Realignment of the signal from a single line-of-sight to remove physiological tissue motion is a critical part of the process of small-vessel flow mapping, and our methods for this alignment are considered in this paper. Each method involves the correlation of pulses acquired from the same line-of-sight. The first method involves the correlation of adjacent pulses (nearest-neighbor), the second involves a single reference line and the third involves averaging the correlation over a set of reference lines. We find that a nearest-neighbor strategy is suboptimal, and that strategies involving a global reference line are superior. A bound on the variance of estimates of the location of the correlation peak is presented. This bound allows us to consider our results in comparison with an absolute limit. Finally, a new algorithm allowing for alignment between lines-of-sight is described, and initial results are presented. Such an algorithm does, in fact, reduce jitter, correct for tissue motion and enables us to better visualize vessel continuity. We find that vessels as small as 40 μm can be mapped in two dimensions using a 50-MHz transducer.

KW - Blood flow mapping

KW - Cross-correlation

KW - Signal alignment

KW - Velocity estimation

UR - http://www.scopus.com/inward/record.url?scp=0032127782&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0032127782&partnerID=8YFLogxK

U2 - 10.1016/S0301-5629(98)00042-8

DO - 10.1016/S0301-5629(98)00042-8

M3 - Article

C2 - 9740383

AN - SCOPUS:0032127782

VL - 24

SP - 809

EP - 824

JO - Ultrasound in Medicine and Biology

JF - Ultrasound in Medicine and Biology

SN - 0301-5629

IS - 6

ER -