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Connecting CMR and Physiology : Expanding the capabilities of cardiovascular magnetic resonance in quantifying physiology

Seemann, Felicia LU (2019) In Report 5/19 1.
Abstract
The assessment of cardiovascular physiology is crucial to facilitate clinical diagnostics, treatment, and research. Physiology and anatomy can be assessed noninvasively using cardiovascular magnetic resonance (CMR), a versatile and reliable medical imaging modality free from ionizing radiation. CMR is capable of providing a vast amount of information such as displacement, velocity, flow, length, area, volume, and tissue properties. Considered the gold standard for noninvasive quantification of cardiac function and morphology, CMR is increasingly envisioned as a future one-stop-shop imaging examination for cardiovascular disease. However, quantification of important physiological aspects such as valvular motion, pressure, and force are... (More)
The assessment of cardiovascular physiology is crucial to facilitate clinical diagnostics, treatment, and research. Physiology and anatomy can be assessed noninvasively using cardiovascular magnetic resonance (CMR), a versatile and reliable medical imaging modality free from ionizing radiation. CMR is capable of providing a vast amount of information such as displacement, velocity, flow, length, area, volume, and tissue properties. Considered the gold standard for noninvasive quantification of cardiac function and morphology, CMR is increasingly envisioned as a future one-stop-shop imaging examination for cardiovascular disease. However, quantification of important physiological aspects such as valvular motion, pressure, and force are still not accessible or readily available when using CMR.

The general aim of this thesis was therefore to expand the current capabilities of CMR to include new reliable methods and tools for quantification of the atrioventricular plane displacement, transmitral flow, pressure, and ventricular force-length loops, hence allowing a more complete assessment of subject-specific cardiovascular physiology that could potentially be achieved in a single noninvasive examination.

In this thesis, the current capabilities of CMR were expanded by developing and validating four new methods for quantification of physiology. In Study I, an imaging processing algorithm for feature-tracking of the atrioventricular plane displacement was proposed. The combination of this algorithm and a phase contrast CMR sequence was proposed in Study II to improve measurements of transvalvular flow, which are challenging due to the significant movement of the atrioventricular valves over the cardiac cycle. In Study III, CMR imaging, a noninvasive brachial pressure, and mathematical modelling was combined to enable a noninvasive quantification of left ventricular pressure-volume loops. Study IV used the atrioventricular plane displacement algorithm and the noninvasive pressure-volume loop technique to propose a novel method for evaluation of ventricular force-length loops, which was used to describe the energetics of longitudinal and radial pumping mechanics.

The proposed methods in Study I, II, and IV require only brachial pressure and images which are typically acquired during standard clinical CMR scanning. Addition of the sequence in Study II would prolong a CMR protocol by a few minutes, suggesting that the capabilities of CMR to evaluate cardiovascular physiology during a single noninvasive examination have been expanded, thus getting closer to the one-stop-shop vision for CMR. (Less)
Abstract (Swedish)
Hjärt-kärlsjukdom är den vanligaste dödsorsaken i världen. Tidig diagnos och individanpassad vård är viktigt för att kunna behandla hjärtsjuka patienter. Ny teknik kan möjliggöra framtagandet av nya och förbättrade underlag som behövs för diagnos och behandlingsplan av många hjärtsjuka patienter. Därför har nya analysverktyg som utökar mängden fysiologisk information som går att utvinna ur en enda medicinsk undersökning av hjärtat tagits fram. Detta kan potentiellt förbättra individanpassad vård och forskning då diagnostik, behandlingsplaner och forskningsundersökningar kan genomföras vid ett och samma tillfälle.

Magnetkameror kan användas för att ta medicinska bilder inuti kroppen med hög kvalitet utan varken kirurgiska ingrepp... (More)
Hjärt-kärlsjukdom är den vanligaste dödsorsaken i världen. Tidig diagnos och individanpassad vård är viktigt för att kunna behandla hjärtsjuka patienter. Ny teknik kan möjliggöra framtagandet av nya och förbättrade underlag som behövs för diagnos och behandlingsplan av många hjärtsjuka patienter. Därför har nya analysverktyg som utökar mängden fysiologisk information som går att utvinna ur en enda medicinsk undersökning av hjärtat tagits fram. Detta kan potentiellt förbättra individanpassad vård och forskning då diagnostik, behandlingsplaner och forskningsundersökningar kan genomföras vid ett och samma tillfälle.

Magnetkameror kan användas för att ta medicinska bilder inuti kroppen med hög kvalitet utan varken kirurgiska ingrepp eller strålning. Hjärtbilder tagna med magnetkameror kan används för att utvärdera hjärtats anatomi och pumpförmåga. Utvärderingen sker med hjälp av datorprogram som bland annat kan mäta volymer, förskjutning, hastighet och blodflöden. Den tekniska utvecklingen har hittills inte tillåtit mätning av en del viktig information ur bilderna, som till exempel tryck och kraft. En annan utmaning har varit bildtagning av hjärtklaffarna eftersom de rör sig fram och tillbaka under hjärtslaget.

I denna avhandling har fyra nya metoder för att mäta kardiovaskulär fysiologi utifrån magnetresonansbilder av hjärtat utvecklats och verifierats. I första studien utvecklades ett verktyg som kan detektera och mäta hjärtklaffarnas rörelsemönster. I den andra studien kombinerades detta verktyg med en ny bildtagningsmetod för att kunna mäta blodflödet genom klaffarna. För att kunna få information om hur tryck och volym varierar över hjärtcykeln framställdes en ny metod som kombinerar bildanalys och matematisk modellering. I den fjärde och sista studien möjliggjordes utvärderingen av krafter som verkar i hjärtkammaren, som i sin tur kan användas för att beräkna olika aspekter av hur hjärtat förbrukar energi.

En magnetkameraundersökning tar i dagsläget ca 40-60 minuter. Bilderna som används i tre av studierna är sådana som samlas rutinmässigt, och att lägga till den nya bildtagningsmetoden framtagen i den andra studien utökar endast undersökningstiden med ett par minuter.

Tillsammans utvidgar dessa nya verktyg magnetkamerans förmåga för bedömningar av hjärtat utan att nämnvärt utöka undersökningstiden, vilket innebär att vi närmar oss verkligheten av en mer tidseffektiv, omfattande och individanpassad diagnostik av hjärt-kärl-sjukdomar. (Less)
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author
supervisor
opponent
  • Prof. Muthurangu, Vivek, University College London, United Kingdom.
organization
alternative title
Sammankoppling av CMR och fysiologi : Utökandet av kapaciteten för kardiovaskulär magnetresonanstomografi i kvantifieringen av fysiologi
publishing date
type
Thesis
publication status
published
subject
keywords
Kardiovaskulär magnetresonanstomografi, Fysiologi, Atrioventrikulär klaffplansrörlighet, Mitralisflöde, Tryck-volym loopar, Kraft-längd loopar, Cardiovascular magnetic resonance, Physiology, Atrioventricular plane displacement, Transmitral flow, pressure-volume loops, Ventricular force-length loops
in
Report 5/19
volume
1
pages
108 pages
publisher
Department of Biomedical Engineering, Lund university
defense location
Lecture hall 2, Main building “Blocket”, Entrégatan 7, Skåne University Hospital, Lund
defense date
2019-12-06 09:00:00
ISBN
978-91-7895-328-8
978-91-7895-329-5
language
English
LU publication?
yes
id
82d3ec53-e219-407a-b382-7ca91ba0c350
date added to LUP
2019-10-30 16:39:37
date last changed
2019-11-12 14:29:41
@phdthesis{82d3ec53-e219-407a-b382-7ca91ba0c350,
  abstract     = {The assessment of cardiovascular physiology is crucial to facilitate clinical diagnostics, treatment, and research. Physiology and anatomy can be assessed noninvasively using cardiovascular magnetic resonance (CMR), a versatile and reliable medical imaging modality free from ionizing radiation. CMR is capable of providing a vast amount of information such as displacement, velocity, flow, length, area, volume, and tissue properties. Considered the gold standard for noninvasive quantification of cardiac function and morphology, CMR is increasingly envisioned as a future one-stop-shop imaging examination for cardiovascular disease. However, quantification of important physiological aspects such as valvular motion, pressure, and force are still not accessible or readily available when using CMR. <br/><br/>The general aim of this thesis was therefore to expand the current capabilities of CMR to include new reliable methods and tools for quantification of the atrioventricular plane displacement, transmitral flow, pressure, and ventricular force-length loops, hence allowing a more complete assessment of subject-specific cardiovascular physiology that could potentially be achieved in a single noninvasive examination.<br/><br/>In this thesis, the current capabilities of CMR were expanded by developing and validating four new methods for quantification of physiology. In Study I, an imaging processing algorithm for feature-tracking of the atrioventricular plane displacement was proposed. The combination of this algorithm and a phase contrast CMR sequence was proposed in Study II to improve measurements of transvalvular flow, which are challenging due to the significant movement of the atrioventricular valves over the cardiac cycle. In Study III, CMR imaging, a noninvasive brachial pressure, and mathematical modelling was combined to enable a noninvasive quantification of left ventricular pressure-volume loops. Study IV used the atrioventricular plane displacement algorithm and the noninvasive pressure-volume loop technique to propose a novel method for evaluation of ventricular force-length loops, which was used to describe the energetics of longitudinal and radial pumping mechanics.<br/><br/>The proposed methods in Study I, II, and IV require only brachial pressure and images which are typically acquired during standard clinical CMR scanning. Addition of the sequence in Study II would prolong a CMR protocol by a few minutes, suggesting that the capabilities of CMR to evaluate cardiovascular physiology during a single noninvasive examination have been expanded, thus getting closer to the one-stop-shop vision for CMR.},
  author       = {Seemann, Felicia},
  isbn         = {978-91-7895-328-8},
  language     = {eng},
  month        = {10},
  publisher    = {Department of Biomedical Engineering, Lund university},
  school       = {Lund University},
  series       = {Report 5/19},
  title        = {Connecting CMR and Physiology : Expanding the capabilities of cardiovascular magnetic resonance in quantifying physiology},
  url          = {https://lup.lub.lu.se/search/ws/files/71249167/PhD_Thesis_Kappa_Felicia_Seemann.pdf},
  volume       = {1},
  year         = {2019},
}