Automated Assessment Of Blood Flow In The Cardiovascular System Using 4d Flow Mri

Download Automated Assessment Of Blood Flow In The Cardiovascular System Using 4d Flow Mri full books in PDF, epub, and Kindle. Read online Automated Assessment Of Blood Flow In The Cardiovascular System Using 4d Flow Mri ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!

Automated Assessment of Blood Flow in the Cardiovascular System Using 4D Flow MRI

Author : Mariana Bustamante
Publisher : Linköping University Electronic Press
ISBN 13 : 9176853462
Total Pages : 77 pages
Book Rating : 4.1/5 (768 download)

DOWNLOAD NOW!

Book Synopsis Automated Assessment of Blood Flow in the Cardiovascular System Using 4D Flow MRI by : Mariana Bustamante

Download or read book Automated Assessment of Blood Flow in the Cardiovascular System Using 4D Flow MRI written by Mariana Bustamante and published by Linköping University Electronic Press. This book was released on 2018-03-23 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: Medical image analysis focuses on the extraction of meaningful information from medical images in order to facilitate clinical assessment, diagnostics and treatment. Image processing techniques have gradually become an essential part of the modern health care system, a consequence of the continuous technological improvements and the availability of a variety of medical imaging techniques. Magnetic Resonance Imaging (MRI) is an imaging technique that stands out as non-invasive, highly versatile, and capable of generating high quality images without the use of ionizing radiation. MRI is frequently performed in the clinical setting to assess the morphology and function of the heart and vessels. When focusing on the cardiovascular system, blood flow visualization and quantification is essential in order to fully understand and identify related pathologies. Among the variety of MR techniques available for cardiac imaging, 4D Flow MRI allows for full three-dimensional spatial coverage over time, also including three-directional velocity information. It is a very powerful technique that can be used for retrospective analysis of blood flow dynamics at any location in the acquired volume. In the clinical routine, however, flow analysis is typically done using two-dimensional imaging methods. This can be explained by their shorter acquisition times, higher in-plane spatial resolution and signal-to-noise ratio, and their relatively simpler post-processing requirements when compared to 4D Flow MRI. The extraction of useful knowledge from 4D Flow MR data is especially challenging due to the large amount of information included in these images, and typically requires substantial user interaction. This thesis aims to develop and evaluate techniques that facilitate the post-processing of thoracic 4D Flow MRI by automating the steps necessary to obtain hemodynamic parameters of interest from the data. The proposed methods require little to no user interaction, are fairly quick, make effective use of the information available in the four-dimensional images, and can easily be applied to sizable groups of data.The addition of the proposed techniques to the current pipeline of 4D Flow MRI analysis simplifies and expedites the assessment of these images, thus bringing them closer to the clinical routine. Medicinsk bildanalys fokuserar på extrahering av meningsfull information från medicinska bilder för att underlätta klinisk bedömning, diagnostik, och behandling. Bildbehandlingsteknik har gradvis blivit en viktig del av det moderna sjukvårdsystemet, en följd av de kontinuerliga tekniska förbättringarna och tillgången till en mängd olika medicinska bildtekniker. Magnetic resonanstomografi (MRT) är en bildteknik som är ickeinvasiv, flexibel och kan generera bilder av hög kvalitet utan joniserande strålning. MRT utförs ofta i klinisk miljö för att bedöma anatomi och funktion av hjärtat och blodkärlen. När man fokuserar på hjärt-kärlsystemet är bedömning av blodflödet viktigt för att kunna förstå och identifiera sjukdomar fullt ut. Bland de olika MRT-teknikerna som är tillgängliga för avbildning av hjärtat möjliggör 4D flödes-MRT komplett täckning av hjärtat i tre dimensioner över tid, och med hastighetsinformation i tre riktningar. 4D flödes-MRT är en mycket effektiv metod som kan användas för retrospektiv analys av blodflödesdynamik på vilken position som helst i den avbildade volymen. Till vardags görs dock blodflödesanalysen vanligtvis på bilder tagna med tvådimensionella avbildningsmetoder. Detta kan förklaras av deras kortare insamlingstider, högre spatiella upplösning, bättre signal-brusförhållandet, och att de är relativt enklare att efterbehandla jämfört med 4D flödes-MRT. Utvinningen av användbar information från 4D flödes-MRT-data är väldigt utmanande på grund av den stora mängden information som dessa bilder innehåller och kräver vanligtvis väsentlig användarinteraktion. Denna avhandling syftar till att utveckla och utvärdera metoder som underlättar efterbehandlingen av 4D flödes-MRT genom att automatisera de steg som är nödvändiga för att härleda hemodynamiska parametrarna av intresse från dessa data. De föreslagna metoderna kräver liten eller ingen användarinteraktion, är relativt snabba, använder all information som finns i de fyrdimensionella bilderna, och kan enkelt appliceras på stora datamängder. Tillägget av de i avhandlingen beskrivna metoderna till den nuvarande analysen av 4D flödes-MRT medger en avsevärd förenkling och uppsnabbad utvärdering, vilket gör att den avancerade 4D flödes MRT-tekniken kommer närmare att kunna användas i kliniskt rutinarbete.

Towards Personalized Models of the Cardiovascular System Using 4D Flow MRI

Author : Belén Casas Garcia
Publisher : Linköping University Electronic Press
ISBN 13 : 9176852172
Total Pages : 71 pages
Book Rating : 4.1/5 (768 download)

DOWNLOAD NOW!

Book Synopsis Towards Personalized Models of the Cardiovascular System Using 4D Flow MRI by : Belén Casas Garcia

Download or read book Towards Personalized Models of the Cardiovascular System Using 4D Flow MRI written by Belén Casas Garcia and published by Linköping University Electronic Press. This book was released on 2019-02-15 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current diagnostic tools for assessing cardiovascular disease mostly focus on measuring a given biomarker at a specific spatial location where an abnormality is suspected. However, as a result of the dynamic and complex nature of the cardiovascular system, the analysis of isolated biomarkers is generally not sufficient to characterize the pathological mechanisms behind a disease. Model-based approaches that integrate the mechanisms through which different components interact, and present possibilities for system-level analyses, give us a better picture of a patient’s overall health status. One of the main goals of cardiovascular modelling is the development of personalized models based on clinical measurements. Recent years have seen remarkable advances in medical imaging and the use of personalized models is slowly becoming a reality. Modern imaging techniques can provide an unprecedented amount of anatomical and functional information about the heart and vessels. In this context, three-dimensional, three-directional, cine phase-contrast (PC) magnetic resonance imaging (MRI), commonly referred to as 4D Flow MRI, arises as a powerful tool for creating personalized models. 4D Flow MRI enables the measurement of time-resolved velocity information with volumetric coverage. Besides providing a rich dataset within a single acquisition, the technique permits retrospective analysis of the data at any location within the acquired volume. This thesis focuses on improving subject-specific assessment of cardiovascular function through model-based analysis of 4D Flow MRI data. By using computational models, we aimed to provide mechanistic explanations of the underlying physiological processes, derive novel or improved hemodynamic markers, and estimate quantities that typically require invasive measurements. Paper I presents an evaluation of current markers of stenosis severity using advanced models to simulate flow through a stenosis. Paper II presents a framework to personalize a reduced-order, mechanistic model of the cardiovascular system using exclusively non-invasive measurements, including 4D Flow MRI data. The modelling approach can unravel a number of clinically relevant parameters from the input data, including those representing the contraction and relaxation patterns of the left ventricle, and provide estimations of the pressure-volume loop. In Paper III, this framework is applied to study cardiovascular function at rest and during stress conditions, and the capability of the model to infer load-independent measures of heart function based on the imaging data is demonstrated. Paper IV focuses on evaluating the reliability of the model parameters as a step towards translation of the model to the clinic.

Fast and Accurate 4D Flow MRI for Cardiovascular Blood Flow Assessment

Author : Sven Petersson
Publisher :
ISBN 13 : 9789175195063
Total Pages : pages
Book Rating : 4.1/5 (95 download)

DOWNLOAD NOW!

Book Synopsis Fast and Accurate 4D Flow MRI for Cardiovascular Blood Flow Assessment by : Sven Petersson

Download or read book Fast and Accurate 4D Flow MRI for Cardiovascular Blood Flow Assessment written by Sven Petersson and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Blood flow specific assessment of ventricular function

Author : Alexandru Grigorescu Fredriksson
Publisher : Linköping University Electronic Press
ISBN 13 : 9176854159
Total Pages : 95 pages
Book Rating : 4.1/5 (768 download)

DOWNLOAD NOW!

Book Synopsis Blood flow specific assessment of ventricular function by : Alexandru Grigorescu Fredriksson

Download or read book Blood flow specific assessment of ventricular function written by Alexandru Grigorescu Fredriksson and published by Linköping University Electronic Press. This book was released on 2017-12-06 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: The spectrum of cardiovascular diseases is the leading cause of morbidity and mortality globally. Early assessment and treatment of these conditions, acquired as well as congenital, is therefore of paramount importance. The human heart has a great ability to adapt to various hemodynamic conditions by cardiac remodeling. Pathologic cardiac remodeling can occur as a result of cardiovascular disease in an effort to maintain satisfactory cardiac function. With time, cardiac function diminishes leading to disease progression and subsequent heart failure, the end-point of many heart diseases, associated with very poor prognosis. Within the normal cardiac ventricles blood flows in highly organized patterns, and changes in cardiac configuration or function will affect these flow patterns. Conversely, altered flows and pressures can bring about cardiac remodeling. In congenital heart disease, even after corrective surgery, cardiac anatomy and thereby intracardiac blood flow patterns are inherently altered. The clinically most available imaging technique, ultrasound with Doppler, allows only for one-directional flow assessment and is limited by the need of clear examination windows, thus failing to fully assess the complex three-dimensional blood flow within the beating heart. Cardiovascular magnetic resonance imaging (CMR) with phase-contrast has the ability to acquire three-dimensional (3D), three-directional time resolved velocity data (3D + time = 4D flow data) from which visualization and quantification of blood flow patterns over the complete cardiac cycle can be performed. Four functional blood flow components have previously been defined based on the blood route and distribution through the ventricle, where the inflowing blood that passes directly to the outflow is called Direct flow. From these components, various quantitative measures can be derived, such as component volumes and kinetic energy (KE) throughout the cardiac cycle. In addition, the 4D flow technique has the ability to quantify and visualize turbulent flow with increased velocity fluctuations in the heart and vessels, turbulent kinetic energy (TKE). The technique has been developed and evaluated for assessment of left ventricular (LV) blood flow in healthy subjects and in patients with dilated dysfunctional left ventricles, showing significant changes in blood flow patterns and energetics with disease. There is however still no study addressing the gap in the spectrum from the healthy cohorts to patients with moderate to severe left ventricular remodeling. In Paper III, 4D flow CMR was utilized to assess LV blood flow in patients with subtle LV dysfunction, and a shift in blood flow component volumes and KE was seen from the Direct flow to the non-ejecting blood flow components. In patients with both left- and right-sided acquired and congenital heart disease, right ventricular (RV) function is of great prognostic significance, however this ventricle has historically been somewhat overseen. With its complex geometry, advanced physiology and retrosternal location, assessment of the RV is still challenging and the right ventricular blood flow is still incompletely described. In Paper I, the RV blood flow in healthy subjects was assessed, and the proportionally larger Direct flow component was located in the most basal region of the ventricle and possessed higher levels of KE at end-diastole than the other flow components suggesting that this portion of blood was prepared for efficient systolic ejection. In Paper II, the blood flow was assessed in the RV of patients with subtle primary LV disease, and even if conventional echocardiographic or CMR RV parameters did not show any RV dysfunction, alterations of flow patterns suggestive of RV impairment were found in the patients with the more remodeled LVs. With improvements of the cardiovascular health care, including the surgical techniques, the number of adult patients with surgically corrected complex congenital heart diseases increases, one of which is tetralogy of Fallot (ToF). Surgical repair of ToF involves widening of the pulmonary stenosis, which postoperatively may cause pulmonary insufficiency and regurgitation (PR). Disturbed or turbulent flow patterns are rare in the healthy cardiovascular system. With pathological changes, such as valvular insufficiency, increased amounts of TKE have been demonstrated. Turbulence is known to be harmful to organic tissues and could be significant in the development of ventricular remodeling, such as dilation and other complications seen in Fallot patients. In Paper IV, the RV intraventricular TKE levels were assessed in relation to conventional measures of PR. Results showed that RV TKE was increased in ToF patients with PR compared to healthy controls, and that these 4D flow-specific measures related slightly stronger to indices of RV remodeling than the conventional measures of PR. 4D flow CMR analysis of the intracardiac blood flow has the potential of adding to pathophysiological understanding, and thereby provide useful diagnostic information and contribute to optimization of treatment of heart disease at earlier stages before irreversible and clinically noticeable changes occur. The flow specific measures used in this thesis could be utilized to detect these alterations of intracardiac blood flow and could thus act as potential markers of progressing ventricular dysfunction, pathological remodeling or used for risk stratification in adults with early repair tetralogy of Fallot. Visualizations of intracardiac flow patterns could provide useful information to cardiac/thoracic surgeons pre- and post-operatively.

Cardiac 4D Flow MRI

Author : Philip Corrado (Ph.D.)
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (139 download)

DOWNLOAD NOW!

Book Synopsis Cardiac 4D Flow MRI by : Philip Corrado (Ph.D.)

Download or read book Cardiac 4D Flow MRI written by Philip Corrado (Ph.D.) and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic resonance imaging (MRI) is a medical imaging modality with the ability to acquire images sensitized to several different contrast mechanisms. One of the many mechanisms that can generate contrast in MR images is blood flow. "4D flow MRI", a method for quantifying time-resolved velocity fields in 3-dimensional regions, is employed in the context of comprehensive flow assessment within the heart and major blood vessels but requires long acquisition and post-processing times. The aims of the work presented in this dissertation are to accelerate the acquisition and processing of cardiac 4D flow MRI images, and to apply 4D flow MRI to quantify intracardiac hemodynamics in two disease population: survivors of myocardial infarction and young adults born very-to-extremely premature. This work is divided into six research chapters. The technical innovations introduced and evaluated in my work (Chapters 2-4) relate to the validation of accelerated 4D flow acquisitions and the development of fast, automated pipelines for 4D flow image analysis. In Chapter 2, I describe the construction of a model of the left ventricle of the heart and use it to compare acceleration acquisition techniques for 4D flow MRI. Using an optical imaging-based reference standard, I show lower error in velocity estimations at short scan times for one technique over the other, supporting the use of this technique in scan-time-limited scenarios and demonstrating a generalizable workflow for head-to-head comparison of image acquisition or reconstruction techniques which can be adopted in other applications in order to minimize acquisition time. In Chapters 3 and 4, I use deep learning to automate image processing tasks for quantitative flow assessment in 4D flow MRI of the chest. In particular, I automate the segmentation of the myocardial ventricles (Chapter 3), necessary for the measurement of ventricular kinetic energy or the analysis of ventricular flow components, and the placement of measurement planes (Chapter 4), necessary for the measurement of flow and peak velocity in the great vessels of the heart. Both methods are thoroughly evaluated, finding similar performance to manual segmentation/plane placement. This enables 4D flow MR images of the chest to be processed in an automated fashion, vastly reducing the processing time required for users of 4D flow MRI and enabling large and longitudinal studies without biases between observers. The applications of cardiac 4D flow MRI explored in my work are myocardial infarction (Chapter 5) and cardiac development after preterm birth (Chapters 6-7). In Chapter 5, I apply cardiac 4D flow MRI to study hemodynamics in the left ventricle after acute myocardial infarction. 4D flow data is compared region-by-region between myocardial infarction patients and controls, finding reduced flow in several left ventricular regions in patients relative to controls, perhaps providing indications of risk of post-infarction sequelae. In Chapters 6 and 7, I apply cardiac 4D flow MRI to study intracardiac hemodynamics in another at-risk population: young adults born very-to-extremely premature. I first compare intraventricular flow in young adults born premature to those born at term (Chapter 6), finding decreased right ventricular early-to-late diastolic kinetic energy ratios and increased viscous energy dissipation in preterm subjects relative to term subjects, suggesting altered right ventricular filling which may be relevant to the elevated early heart failure risk in this population. I then use acute pharmacological interventions to assess the effects of hemodynamic manipulations on cardiac hemodynamics measured by 4D flow MRI in young adults born premature (Chapter 7). Acute pharmacological reduction of pulmonary blood pressure increases cardiac function, suggesting that pulmonary hypertension may play a role in this group's heart failure risk. Recommendations for future work include assembling large multicenter databases aimed at using 4D flow to predict cardiovascular outcomes in the general population, a longitudinal 4D flow study of the developing preterm heart throughout childhood, and a prospective 4D flow study to predict post-myocardial infarction thrombus formation.

Cardiac 4D Flow MRI

Author : Philip Corrado (Ph.D.)
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (138 download)

DOWNLOAD NOW!

Book Synopsis Cardiac 4D Flow MRI by : Philip Corrado (Ph.D.)

Improving Assessments of Hemodynamics and Vascular Disease

Author : Magnus Ziegler
Publisher : Linköping University Electronic Press
ISBN 13 : 9176850986
Total Pages : 64 pages
Book Rating : 4.1/5 (768 download)

DOWNLOAD NOW!

Book Synopsis Improving Assessments of Hemodynamics and Vascular Disease by : Magnus Ziegler

Download or read book Improving Assessments of Hemodynamics and Vascular Disease written by Magnus Ziegler and published by Linköping University Electronic Press. This book was released on 2019-04-24 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Blood vessels are more than simple pipes, passively enabling blood to pass through them. Their form and function are dynamic, changing with both aging and disease. This process involves a feedback loop wherein changes to the shape of a blood vessel affect the hemodynamics, causing yet more structural adaptation. This feedback loop is driven in part by the hemodynamic forces generated by the blood flow, and the distribution and strength of these forces appear to play a role in the initiation, progression, severity, and the outcome of vascular diseases. Magnetic Resonance Imaging (MRI) offers a unique platform for investigating both the form and function of the vascular system. The form of the vascular system can be examined using MR-based angiography, to generate detailed geometric analyses, or through quantitative techniques for measuring the composition of the vessel wall and atherosclerotic plaques. To complement these analyses, 4D Flow MRI can be used to quantify the functional aspect of the vascular system, by generating a full time-resolved three-dimensional velocity field that represents the blood flow. This thesis aims to develop and evaluate new methods for assessing vascular disease using novel hemodynamic markers generated from 4D Flow MRI and quantitative MRI data towards the larger goal of a more comprehensive non-invasive examination oriented towards vascular disease. In Paper I, we developed and evaluated techniques to quantify flow stasis in abdominal aortic aneurysms to measure this under-explored aspect of aneurysmal hemodynamics. In Paper II, the distribution and intensity of turbulence in the aorta was quantified in both younger and older men to understand how aging changes this aspect of hemodynamics. A method to quantify the stresses generated by turbulence that act on the vessel wall was developed and evaluated using simulated flow data in Paper III, and in Paper V this method was utilized to examine the wall stresses of the carotid artery. The hemodynamics of vascular disease cannot be uncoupled from the anatomical changes the vessel wall undergoes, and therefore Paper IV developed and evaluated a semi-automatic method for quantifying several aspects of vessel wall composition. These developments, taken together, help generate more valuable information from imaging data, and can be pooled together with other methods to form a more comprehensive non-invasive examination for vascular disease.

Four-Dimensional Flow Magnetic Resonance Imaging and Applications in Cardiology

Author : Julio Garcia
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (139 download)

DOWNLOAD NOW!

Book Synopsis Four-Dimensional Flow Magnetic Resonance Imaging and Applications in Cardiology by : Julio Garcia

Download or read book Four-Dimensional Flow Magnetic Resonance Imaging and Applications in Cardiology written by Julio Garcia and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Blood flow through the heart and great vessels moves in three dimensions (3D) throughout time. However, the assessment of its 3D nature has been limited in the human body. Recent advances in magnetic resonance imaging (MRI) allow for the comprehensive visualization and quantification of in-vivo flow dynamics using four-dimensional (4D) flow MRI. In addition, this technique provides the opportunity to obtain advanced hemodynamic biomarkers such as vorticity, helicity, wall shear stress (WSS), pressure gradients, viscous energy loss (EL), and turbulent kinetic energy (TKE). This chapter will introduce 4D flow MRI which is currently used for blood flow visualization and advanced quantification of cardiac hemodynamic biomarkers. We will discuss its advantages relative to other in-vivo flow imaging techniques and describe its potential clinical applications in cardiology.

Cardiovascular Imaging and Image Analysis

Author : Ayman El-Baz
Publisher : CRC Press
ISBN 13 : 0429806221
Total Pages : 436 pages
Book Rating : 4.4/5 (298 download)

DOWNLOAD NOW!

Book Synopsis Cardiovascular Imaging and Image Analysis by : Ayman El-Baz

Download or read book Cardiovascular Imaging and Image Analysis written by Ayman El-Baz and published by CRC Press. This book was released on 2018-10-03 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the state-of-the-art approaches for automated non-invasive systems for early cardiovascular disease diagnosis. It includes several prominent imaging modalities such as MRI, CT, and PET technologies. There is a special emphasis placed on automated imaging analysis techniques, which are important to biomedical imaging analysis of the cardiovascular system. Novel 4D based approach is a unique characteristic of this product. This is a comprehensive multi-contributed reference work that will detail the latest developments in spatial, temporal, and functional cardiac imaging. The main aim of this book is to help advance scientific research within the broad field of early detection of cardiovascular disease. This book focuses on major trends and challenges in this area, and it presents work aimed to identify new techniques and their use in biomedical image analysis. Key Features: Includes state-of-the art 4D cardiac image analysis Explores the aspect of automated segmentation of cardiac CT and MR images utilizing both 3D and 4D techniques Provides a novel procedure for improving full-cardiac strain estimation in 3D image appearance characteristics Includes extensive references at the end of each chapter to enhance further study

Deep Learning for Automated Analysis of Cardiac Imaging

Author :
Publisher :
ISBN 13 : 9789464831856
Total Pages : 0 pages
Book Rating : 4.8/5 (318 download)

DOWNLOAD NOW!

Book Synopsis Deep Learning for Automated Analysis of Cardiac Imaging by :

Download or read book Deep Learning for Automated Analysis of Cardiac Imaging written by and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Quantitative Analysis of Blood Flow and Vessel Wall Parameters Using 4D-flow Sensitive MRI

Author : Aurélien F. Stalder
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (118 download)

DOWNLOAD NOW!

Book Synopsis Quantitative Analysis of Blood Flow and Vessel Wall Parameters Using 4D-flow Sensitive MRI by : Aurélien F. Stalder

Download or read book Quantitative Analysis of Blood Flow and Vessel Wall Parameters Using 4D-flow Sensitive MRI written by Aurélien F. Stalder and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Guided Qualitative and Quantitative Analysis of Cardiac 4D PC-MRI Blood Flow Data

Author : Benjamin Köhler
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (96 download)

DOWNLOAD NOW!

Book Synopsis Guided Qualitative and Quantitative Analysis of Cardiac 4D PC-MRI Blood Flow Data by : Benjamin Köhler

Download or read book Guided Qualitative and Quantitative Analysis of Cardiac 4D PC-MRI Blood Flow Data written by Benjamin Köhler and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Novel Fast 4D Phase Contrast Velocity Mapping MRI Sequences and Their Application on Cardiovascular Hemodynamics

Author : Ali Nahardani
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (142 download)

DOWNLOAD NOW!

Book Synopsis Novel Fast 4D Phase Contrast Velocity Mapping MRI Sequences and Their Application on Cardiovascular Hemodynamics by : Ali Nahardani

Download or read book Novel Fast 4D Phase Contrast Velocity Mapping MRI Sequences and Their Application on Cardiovascular Hemodynamics written by Ali Nahardani and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 4D-flow velocity mapping is a technique in magnetic resonance imaging (MRI) to quantify blood flow velocity in 3D space and over time. To increase accuracy, novel sequences have been developed to overcome its technical limitations, including the low signal-to-noise ratio (SNR), low velocity-to-noise ratio (VNR), background velocity fluctuations due to concomitant fields, and flow-related intra-voxel dephasing. However, for a long time, this field was almost untouched in preclinical imaging until Krämer et al. (2017) developed the self-gated ultra-short-echo 4D-flow (UTE-4D-flow) technique. Although UTE-4D-flow showed superior SNR and VNR compared to the conventional prospectively-gated Cartesian-4D-flow method, its total scan time was too long to be applied in routine practice, especially in bigger animals than mice. To shorten the total scan time and preserve SNR and VNR, we combined the concepts of UTE-4D-flow and Cartesian-4D-flow techniques, which resulted in a Stack-of-Stars 4D-flow (SoS-4D-flow) sequence. The in-vitro evaluations of the sequence proved that it benefited from an improved SNR, VNR, and background velocity bias compared to the Cartesian counterpart. Thereafter, we applied the sequence on rats by integrating it into a prospective-gating system. The initial results prompted us to quantify the pulmonary and vena-cava venous blood flow in addition to arterial hemodynamics. The later study resulted in a novel diagnostic marker - “the pulmonary arteriovenous pressure gradient” - to diagnose pulmonary arterial hypertension non-invasively by MRI. Finally, by refining the sequence and replacing the prospective-gating system with a retrospective k0-navigator and compressed sensing (CS) reconstruction, we could shorten the scan time to almost half the measurement time in the UTE-4D-flow sequence. Finally, we tested the sequence on phantoms and mice, and could confirm the expected advantages which the previous study on rats revealed.

Valvular and Coronary Blood Flow Quantification by Cardiac 4D Flow MRI

Author : Carmen P. S. Blanken
Publisher :
ISBN 13 : 9789464216028
Total Pages : 179 pages
Book Rating : 4.2/5 (16 download)

DOWNLOAD NOW!

Book Synopsis Valvular and Coronary Blood Flow Quantification by Cardiac 4D Flow MRI by : Carmen P. S. Blanken

Download or read book Valvular and Coronary Blood Flow Quantification by Cardiac 4D Flow MRI written by Carmen P. S. Blanken and published by . This book was released on 2022 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Advancing Functional Assessment with Flow-sensitive Magnetic Resonance Imaging

Author : Grant Steven Roberts (Ph.D.)
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (139 download)

DOWNLOAD NOW!

Book Synopsis Advancing Functional Assessment with Flow-sensitive Magnetic Resonance Imaging by : Grant Steven Roberts (Ph.D.)

Download or read book Advancing Functional Assessment with Flow-sensitive Magnetic Resonance Imaging written by Grant Steven Roberts (Ph.D.) and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phase-contrast magnetic resonance imaging (PC-MRI) is a non-invasive imaging method capable of quantifying time-resolved hemodynamics. This dissertation aims to develop novel acquisition methods and post-processing tools for the robust assessment of intracranial and aortic hemodynamics using PC-MRI and to study their relationship with aging and neurodegeneration. The associations between cerebrovascular health, arterial stiffness, aging, and neurodegeneration are poorly understood. 4D flow MRI is a noninvasive, quantitative imaging technique well-suited for the comprehensive assessment of cerebrovascular anatomy and function. However, its use in large-scale studies and clinical translation requires automation and robustness to accurately visualize and quantify hemodynamic parameters of interest. Currently, no adequate freely-available analysis tools exist and commercial post-processing packages are targeted toward cardiac applications. Here, I develop and validate a method to improve 4D flow MRI streamlines for generating 'virtual injections', enabling visualization of complex blood flow patterns in the brain. In addition, I introduce and validate an automated tool designed for simplified, robust, and reproducible cranial 4D flow MRI analysis, reducing post-processing times and interobserver variability. This tool is subsequently used to establish normative intracranial hemodynamics in one of the largest 4D flow studies to date from 759 older adults. Blood flow rates and pulsatility indices are tabulated in all major intracranial vessels and show a strong age dependency. This tool is also used to assess the relationship between cerebrovascular hemodynamics and white matter microstructure in cognitively unimpaired and Alzheimer's disease subjects. We find that white matter integrity is reduced in Alzheimer's disease and that white matter microstructure correlates with cerebral blood flow and pulsatility in cognitively unimpaired subjects. Furthermore, aortic stiffening, caused by aging or cardiovascular disease, can propagate harmful pulsatility into the cerebral microvasculature. PC-MRI methods have been developed to probe aortic stiffness by measuring pulse wave velocity (PWV), however, temporal resolution and breath-holds are methodological limitations, particularly in older adults. A free-breathing, radial, 2D-PC sequence with advanced image reconstruction is introduced to overcome these limitations and is validated in a custom-manufactured aortic phantom. Obtained PWVs are repeatable and comparable to standard breath-hold sequences. The image acquisition is further advanced by using a simultaneous multislice acquisition and reconstruction methodology to acquire two PC slices simultaneously which reduces scan time, improves physiological consistency, and maintains image quality. Together, these novel post-processing and acquisition techniques provide a means to quantitatively and comprehensively assess both intracranial and aortic vascular health. Using these techniques, a strong relationship between aging, aortic stiffness, cerebral blood flow and pulsatility, and white matter integrity was observed in older adults. These methods and results will help elucidate the pathophysiological contributions of vascular health in the context of aging and neurodegeneration.

Blood Flow Specific Assessment of Ventricular Function

Author : Alexandru Grigorescu Fredriksson
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (12 download)

DOWNLOAD NOW!

Book Synopsis Blood Flow Specific Assessment of Ventricular Function by : Alexandru Grigorescu Fredriksson

Download or read book Blood Flow Specific Assessment of Ventricular Function written by Alexandru Grigorescu Fredriksson and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The spectrum of cardiovascular diseases is the leading cause of morbidity and mortality globally. Early assessment and treatment of these conditions, acquired as well as congenital, is therefore of paramount importance. The human heart has a great ability to adapt to various hemodynamic conditions by cardiac remodeling. Pathologic cardiac remodeling can occur as a result of cardiovascular disease in an effort to maintain satisfactory cardiac function. With time, cardiac function diminishes leading to disease progression and subsequent heart failure, the end-point of many heart diseases, associated with very poor prognosis. Within the normal cardiac ventricles blood flows in highly organized patterns, and changes in cardiac configuration or function will affect these flow patterns. Conversely, altered flows and pressures can bring about cardiac remodeling. In congenital heart disease, even after corrective surgery, cardiac anatomy and thereby intracardiac blood flow patterns are inherently altered. The clinically most available imaging technique, ultrasound with Doppler, allows only for one-directional flow assessment and is limited by the need of clear examination windows, thus failing to fully assess the complex three-dimensional blood flow within the beating heart. Cardiovascular magnetic resonance imaging (CMR) with phase-contrast has the ability to acquire three-dimensional (3D), three-directional time resolved velocity data (3D + time = 4D flow data) from which visualization and quantification of blood flow patterns over the complete cardiac cycle can be performed. Four functional blood flow components have previously been defined based on the blood route and distribution through the ventricle, where the inflowing blood that passes directly to the outflow is called Direct flow . From these components, various quantitative measures can be derived, such as component volumes and kinetic energy (KE) throughout the cardiac cycle. In addition, the 4D flow technique has the ability to quantify and visualize turbulent flow with increased velocity fluctuations in the heart and vessels, turbulent kinetic energy (TKE). The technique has been developed and evaluated for assessment of left ventricular (LV) blood flow in healthy subjects and in patients with dilated dysfunctional left ventricles, showing significant changes in blood flow patterns and energetics with disease. There is however still no study addressing the gap in the spectrum from the healthy cohorts to patients with moderate to severe left ventricular remodeling. In Paper III , 4D flow CMR was utilized to assess LV blood flow in patients with subtle LV dysfunction, and a shift in blood flow component volumes and KE was seen from the Direct flow to the non-ejecting blood flow components. In patients with both left- and right-sided acquired and congenital heart disease, right ventricular (RV) function is of great prognostic significance, however this ventricle has historically been somewhat overseen. With its complex geometry, advanced physiology and retrosternal location, assessment of the RV is still challenging and the right ventricular blood flow is still incompletely described. In Paper I , the RV blood flow in healthy subjects was assessed, and the proportionally larger Direct flow component was located in the most basal region of the ventricle and possessed higher levels of KE at end-diastole than the other flow components suggesting that this portion of blood was prepared for efficient systolic ejection. In Paper II , the blood flow was assessed in the RV of patients with subtle primary LV disease, and even if conventional echocardiographic or CMR RV parameters did not show any RV dysfunction, alterations of flow patterns suggestive of RV impairment were found in the patients with the more remodeled LVs. With improvements of the cardiovascular health care, including the surgical techniques, the number of adult patients with surgically corrected complex congenital heart diseases increases, one of which is tetralogy of Fallot (ToF). Surgical repair of ToF involves widening of the pulmonary stenosis, which postoperatively may cause pulmonary insufficiency and regurgitation (PR). Disturbed or turbulent flow patterns are rare in the healthy cardiovascular system. With pathological changes, such as valvular insufficiency, increased amounts of TKE have been demonstrated. Turbulence is known to be harmful to organic tissues and could be significant in the development of ventricular remodeling, such as dilation and other complications seen in Fallot patients. In Paper IV , the RV intraventricular TKE levels were assessed in relation to conventional measures of PR. Results showed that RV TKE was increased in ToF patients with PR compared to healthy controls, and that these 4D flow-specific measures related slightly stronger to indices of RV remodeling than the conventional measures of PR. 4D flow CMR analysis of the intracardiac blood flow has the potential of adding to pathophysiological understanding, and thereby provide useful diagnostic information and contribute to optimization of treatment of heart disease at earlier stages before irreversible and clinically noticeable changes occur. The flow specific measures used in this thesis could be utilized to detect these alterations of intracardiac blood flow and could thus act as potential markers of progressing ventricular dysfunction, pathological remodeling or used for risk stratification in adults with early repair tetralogy of Fallot. Visualizations of intracardiac flow patterns could provide useful information to cardiac/thoracic surgeons pre- and post-operatively.

4D Reduced TE (RTE) Spiral Phase Contrast NRI for Rapid Quantification and Visualization of Blood Flow and Hemodynamics

Author : Mohammadjavad Negahdar
Publisher :
ISBN 13 :
Total Pages : 158 pages
Book Rating : 4.:/5 (938 download)

DOWNLOAD NOW!

Book Synopsis 4D Reduced TE (RTE) Spiral Phase Contrast NRI for Rapid Quantification and Visualization of Blood Flow and Hemodynamics by : Mohammadjavad Negahdar

Download or read book 4D Reduced TE (RTE) Spiral Phase Contrast NRI for Rapid Quantification and Visualization of Blood Flow and Hemodynamics written by Mohammadjavad Negahdar and published by . This book was released on 2015 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: 4D flow Phase Contrast MRI is a relatively new technique in MRI which is capable of deriving time-resolved three-dimensional velocity fields in a 3D volume noninvasively. 4D flow imaging is a 3D k-space acquisition where for the third dimension, an additional phase-encoding step is required. The velocity field can then be used to obtain flow waveform, wall shear stress, vascular compliance, blood pressure, and other hemodynamic information. A significant limitation of 4D flow methods has been the requisite long scan times, requiring the patient to remain motionless at times on the order of 10-20 minutes, depending on scan parameters. The scan times may become more prohibitive in case of 4D cardiovascular studies where respiratory gating with navigator echoes is required. In this thesis the feasibility of using a reduced TE stack of spirals k-space acquisition for 4D flow imaging are investigated. Starting with fundamentals of MRI, the basics of Phase contrast and 4D flow MRI are thoroughly discussed in Chapter 1-3 and subsequently experimental phantom results are reported in Chapter 4, pointing to the feasibility of performing highly accurate 4D velocity and flow measurement with the proposed pulse sequence under a variety of flow conditions and with substantial reductions in scan time when compared to conventional 4D flow. In phantom studies, results based on the root mean square error criterion indicate that 4D Reduced TE (RTE) Spiral PC MRI is capable of providing the same level of accuracy as conventional 4D conventional PC MRI but in a much shorter scan time (30% reduction in scan time when imaging an FOV of 100*100*60 mm3 and spatial resolution of 1.5*1.5*3 mm3). Moreover, the proposed method has the added advantage of achieving the shorter echo time of 2 ms versus 3.6 ms for conventional 4D flow at Q=50ml/s and 1.57 ms versus 3.2 ms at the higher flow rate of Q=150 ml/s leading to more accurate assessment of flow distal to narrowings. Statistical results indicate that at low flow rates performance of both methods are similar. At higher flow rates, however, 4D RTE spiral flow achieves better accuracy. Qualitative results in phantom studies also revealed that at higher flow rates, better flow visualization was achieved with4D RTE spiral flow compared with conventional 4D flow. In the second part of Chapter 4, we also report on application of the proposed sequence, in-vivo, to 5 healthy volunteers and 5 subjects with mild to moderate Aortic Stenosis (AS) disease. Results from the proposed method were statistically correlated with velocity profiles derived from conventional 4D flow and Doppler Ultrasound. Results indicate that 4D RTE Spiral is capable of providing the same level of accuracy in flow measurement as Conventional 4D flow MRI for imaging of the aortic valve, but on average resulted in a 30% reduction in scan time and 45% reduction in echo time. 4D RTE Spiral was also able to achieve an echo time of 1.68 ms versus 2.9 ms for that of conventional 4D flow MRI, permitting less signal dephasing in the presence of jet flows distal to occlusions. With Doppler Ultrasound adopted as the reference method, 4D RTE Spiral flow measured peak velocity and maximum pressure gradient with a higher level of accuracy when compared to Conventional 4D flow MRI. Both methods measured left-ventricular out flow tract (LVOT) diameter, Aortic Valve (AV) eject time and time to AV peak with same accuracy. It is concluded that 4D RTE Spiral flow MRI is an excellent technique for flow measurement in cardiac patients who are unable to tolerate longer scan times, currently required by conventional 4D flow methods.