Four-Dimensional Blood Flow Analysis in Patients with Repaired Tetralogy of Fallot: Development of Novel Tools to Analyze Turbulence
Creators: name: Hudani, Ashifa
Publisher: name: Schulich School of Engineering
Year: 2023
Subjects: subject: Medical Imaging
subject: Hemodynamics
subject: 4D Flow
subject: MRI
subject: Cardiovascular
subject: Fluid Dynamics
subject: Education--Sciences
subject: Biophysics
subject: Mathematics
subject: FOS: Mathematics
subject: Engineering
subject: Engineering--Biomedical

description: Medical imaging modalities are used every day and everywhere to obtain valuable information on diagnosis and treatment to help improve patient management along with the future outcome for patients. They enable us to see and understand what is happening within our body without invasive procedures or the need for surgery. Furthermore, these imaging modalities can be used for many diseases and abnormalities that occur within the entire human body due to each modality acquiring a unique attribute in the way it interacts with our tissues resulting in a better understanding of the abnormality or the diseases. Some common imaging modalities that are frequently used today include Magnetic Resonance Imaging (MRI), X-Ray, Computed Tomography, and Ultrasound, just to name a few. Due to the unique ability of these imaging modalities to obtain information, much research and technological improvements have been discovered to obtain as much information as we can for the desired questions at hand. However, MRI is one of the imaging modalities that is known to be non-invasive, does not use ionizing radiation, is very versatile, and can produce high-quality images for many diseases and abnormalities. MRI is commonly used to evaluate the function and morphology of the entire heart along with the surrounding vessels. Furthermore, due to the powerful ability of this imaging modality, it can quantify and visualize blood flow enabling us to better understand the underlying pathophysiology of many cardiac diseases. With further research and development, a newly emerging technique within MRI known as 4D Flow MRI can quantify and visualize blood flow in all three directions (X, Y, Z) throughout the cardiac cycle. Hence, 4D Flow MRI provides us with information on the spatial and temporal progression of 3D blood flow within an entire volumetric coverage of any vascular or cardiac region of interest. Moreover, this imaging modality can retrospectively analyze the patterns of blood flow at any location within the volume of interest along with assessing abnormal hemodynamic fluctuations, especially in patients with Congenital Heart Diseases (CHD). However, currently, 2D MRI is the current imaging method that is used for flow analysis within these patient cohorts. This may be due to 2D MRI having a quicker acquisition time, larger signal-to-noise ratio, and a quicker/simpler post-processing time compared to 4D Flow MRI. Although, 4D Flow MRI provides us with additional information that cannot be obtained from 2D MRI which can help with patient management and clinical decision-making among patients with CHD. Hence, this thesis aims to evaluate how 4D Flow MRI can be used to evaluate turbulent kinetic energy (TKE) in the entire heart within patients with rTOF and healthy controls. Currently, there is very little literature evaluating TKE within this patient cohort, however, is seen to be elevated within the heart of this patient cohort. This thesis also aims to compare accelerated imaging techniques including k-t GRAPPA and compressed sensing on TKE measurements within the pulmonary artery and aorta of healthy controls. Currently, there is no research comparing the two techniques. Hence, this aim will provide further insight into if different accelerating techniques impact various hemodynamic measurements. Lastly, this thesis also aims to develop simple visualization techniques for the aorta, pulmonary artery, left atrium, left ventricle, right atrium, and right ventricle to facilitate reporting of hemodynamic parameters obtained from 4D Flow MRI within the entire heart.