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Non-invasive ultrasound measurements of vascular impedance : Rekindling an old in-house concept on in vivo measurements

Larsson, Roger LU (2019)
Abstract
Despite its introduction in the early 1950´s, vascular impedance has yet to be applied in clinical use to predict early stages of cardiovascular disease (CVD). It is defined as the ratio between blood pressure and flow and describes the opposition to blood flow within the cardiovascular system.

During this thesis project, local pulse wave velocity (PWV) and vascular impedance was estimated from in vivo ultrafast plane wave imaging recordings of the right common carotid artery in eight healthy human volunteers. Both estimations were based on the tracking of the arteries radial displacement. Motion tracking was performed by using two tracking methods: phase shift (PS)- and iterative phase shift (IPS)-tracking. The IPS-tracking is a... (More)
Despite its introduction in the early 1950´s, vascular impedance has yet to be applied in clinical use to predict early stages of cardiovascular disease (CVD). It is defined as the ratio between blood pressure and flow and describes the opposition to blood flow within the cardiovascular system.

During this thesis project, local pulse wave velocity (PWV) and vascular impedance was estimated from in vivo ultrafast plane wave imaging recordings of the right common carotid artery in eight healthy human volunteers. Both estimations were based on the tracking of the arteries radial displacement. Motion tracking was performed by using two tracking methods: phase shift (PS)- and iterative phase shift (IPS)-tracking. The IPS-tracking is a brand new radial motion tracking method on vessels created during this project by combining existing phase shift- and block matching motion tracking methods in use at the Department of Biomedical Engineering, Lund University.

Results showed local PWV-estimations to vary, occasionally to a substantial degree, between, as much as within, volunteer recordings. For the incident pulse wave, probable PWV values totally varied between 1.58 – 7.60 m/s. For the bifurcation wave reflection, probable PWV values totally ranged between 1.06 – 16.09 m/s in the opposite direction. The vascular impedance, defined as vascular characteristic impedance used to estimate vascular input impedance, was in partial successfully determined in two volunteers. The results, however, suggest both local PWV- and vascular impedance estimations to be sensitive to slope fitting of the progressive change in cardiac cycle locations and phase between consecutive scanlines. Furthermore, vascular impedance estimations seem to require longer in vivo recordings containing multiple heart cycles to gain more certain results. (Less)
Abstract (Swedish)
Trots dess introduktion under början av 1950-talet används vaskulär impedans ännu inte i klinisk omfattning för att förutsäga tidiga stadier av hjärt-kärlsjukdomar. Definierad som förhållandet mellan blodtryck och blodflöde beskriver vaskulär impedans motståndet mot blodflödet i det vaskulära systemet.

Under detta avhandlingsprojekt uppskattades den lokala pulsvåghastigheten (PWV) och vaskulära impedansen från in vivo ultrasnabba planvågsbildningsinspelningar över den högra halspulsådern hos åtta friska frivilliga forskningspersoner. Båda uppskattningarna baserades på spårningen av artärens diametraliska rörelsemönster. Spårningen utfördes via två spårningsmetoder: fasförskjutning (PS-tracking) och iterativ fasförskjutning... (More)
Trots dess introduktion under början av 1950-talet används vaskulär impedans ännu inte i klinisk omfattning för att förutsäga tidiga stadier av hjärt-kärlsjukdomar. Definierad som förhållandet mellan blodtryck och blodflöde beskriver vaskulär impedans motståndet mot blodflödet i det vaskulära systemet.

Under detta avhandlingsprojekt uppskattades den lokala pulsvåghastigheten (PWV) och vaskulära impedansen från in vivo ultrasnabba planvågsbildningsinspelningar över den högra halspulsådern hos åtta friska frivilliga forskningspersoner. Båda uppskattningarna baserades på spårningen av artärens diametraliska rörelsemönster. Spårningen utfördes via två spårningsmetoder: fasförskjutning (PS-tracking) och iterativ fasförskjutning (IPS-tracking). IPS-metoden är en helt ny spårningsmetod för radiell rörelse hos kärl, skapad under detta projekt genom att kombinera befintliga fasförskjutnings- och block-matchande rörelsespårningsmetoder i bruk vid Avdelningen för Biomedicinsk Teknik, Lunds Universitet.

Resultaten visar på varierande lokala PWV-uppskattningar, i potentiellt väsentlig grad, mellan, såväl som inom, individuella forskningspersoners inspelningar. Den framåtgående pulsvågen uppvisade troliga PWV-värden mellan 1.58 – 7.60 m/s. För bifurkationspulsvågsreflektionen förekom sannolika PWV-värden mellan 1.06 – 16.09 m/s i motsatt riktning. Den vaskulära impedansen, definierad som vaskulär karakteristisk impedans men som används för att uppskatta vaskulär ingångsimpedans, bestämdes till största del framgångsrikt hos två forskningspersoner. Resultaten föreslår dock att både lokala PWV- och vaskulära impedansuppskattningar är känsliga för lutningsanpassningen efter den progressiva förskjutningen i hjärtcykelfas och fas mellan på varandra följande skanningslinjer. Vidare verkar vaskulära impedansuppskattningar kräva längre in vivo inspelningar med fler hjärtcykler, för att ge mer pålitliga resultat. (Less)
Please use this url to cite or link to this publication:
author
supervisor
organization
alternative title
Icke-invasiva ultraljudsundersökningar av vaskulär impedans : Återuppväckandet av ett gammalt internt koncept på in vivo-mätningar
publishing date
type
Thesis
publication status
published
subject
keywords
Ultraljud, Ultrafast ultrasound imaging, Vaskulär impedans, Pulsvågshastighet, Rörelsespårning, Ultrasound, Ultrafast ultrasound imaging, Vascular impedance, Pulse wave velocity, Motion tracking
pages
125 pages
publisher
LTH
language
English
LU publication?
no
id
c6db1c92-911b-43ad-94c8-558a348370e3
alternative location
http://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=8964711&fileOId=8964713
https://lup.lub.lu.se/student-papers/search/publication/8964711
date added to LUP
2019-09-17 20:41:46
date last changed
2020-06-09 11:08:13
@misc{c6db1c92-911b-43ad-94c8-558a348370e3,
  abstract     = {Despite its introduction in the early 1950´s, vascular impedance has yet to be applied in clinical use to predict early stages of cardiovascular disease (CVD). It is defined as the ratio between blood pressure and flow and describes the opposition to blood flow within the cardiovascular system.<br/><br/>During this thesis project, local pulse wave velocity (PWV) and vascular impedance was estimated from in vivo ultrafast plane wave imaging recordings of the right common carotid artery in eight healthy human volunteers. Both estimations were based on the tracking of the arteries radial displacement. Motion tracking was performed by using two tracking methods: phase shift (PS)- and iterative phase shift (IPS)-tracking. The IPS-tracking is a brand new radial motion tracking method on vessels created during this project by combining existing phase shift- and block matching motion tracking methods in use at the Department of Biomedical Engineering, Lund University.<br/><br/>Results showed local PWV-estimations to vary, occasionally to a substantial degree, between, as much as within, volunteer recordings. For the incident pulse wave, probable PWV values totally varied between 1.58 – 7.60 m/s. For the bifurcation wave reflection, probable PWV values totally ranged between 1.06 – 16.09 m/s in the opposite direction. The vascular impedance, defined as vascular characteristic impedance used to estimate vascular input impedance, was in partial successfully determined in two volunteers. The results, however, suggest both local PWV- and vascular impedance estimations to be sensitive to slope fitting of the progressive change in cardiac cycle locations and phase between consecutive scanlines. Furthermore, vascular impedance estimations seem to require longer in vivo recordings containing multiple heart cycles to gain more certain results.},
  author       = {Larsson, Roger},
  language     = {eng},
  month        = {01},
  publisher    = {LTH},
  title        = {Non-invasive ultrasound measurements of vascular impedance : Rekindling an old in-house concept on in vivo measurements},
  url          = {http://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=8964711&fileOId=8964713},
  year         = {2019},
}