Saudi Cultural Missions Theses & Dissertations
Permanent URI for this communityhttps://drepo.sdl.edu.sa/handle/20.500.14154/10
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Item Restricted Sensitivity of Local Diffusion Tensor Imaging Metrics to Image Resolution for Myocardial Tissue Characterisation.(Saudi Digital Library, 2023-11-23) Alotaibi, Awatif; Irvin, Teh; Jurgen, E. Schneider; Erica, Dall’ArmellinaObjectives: The objective of this study is to introduce novel local diffusion tensor imaging (DTI) metrics within 3x3 local voxel neighbourhoods tailored for cardiac imaging and evaluate their sensitivity to image resolution changes. These metrics include local fractional anisotropy (LFA), local mean diffusivity (LMD), and local angular dispersion (LAD). Methods: Using existing rat heart data, DTI parameter values were calculated across ROIs within the LV at various 3D and 2D resolutions. Repeated measures ANOVA examined the resolution's effect on these values. Additionally, the study simulated "myocardial disarray" to replicate the alignment disruptions observed in heart diseases, aiding in understanding how disease states could affect the parameters. Results: The results showed resolution significantly impacted FA, LFA, and LAD but not MD or LMD. Specifically, FA had a significant sphericity test (F=8.14, p<.001, partial eta2=.670), while LFA was highly significant (p<.001, eta2=.991). However, MD and LMD lacked significance (p=1.000, eta2=0.000). Additionally, LAD demonstrated a highly significant sphericity test (F=107.0, p=.000). Discussion: Image resolution sensitivity varies among local DTI parameters, particularly in LFA and LAD, while LMD remains stable; accounting for these variations is crucial for understanding their clinical implications. The study highlights the impact of severe disarray on LFA and LAD parameters, offering insights that reduce small-scale variations while emphasizing larger-scale trends in the data. Conclusions: Local DTI metrics show promise in characterizing myocardial tissue by capturing broader tensor orientation patterns. Combining local and single-voxel metrics offers complementary data, encouraging further exploration of their advantages in assessing longer- range cardiac disease information.15 0Item Restricted Assessing the Severity and Prognosis in PAH Using Magnetic Resonance Imaging and NT-proBNP(2022) Alandejani, Faisal Abdulwahab; Swift, Andy J; Kiely, David GPulmonary arterial hypertension (PAH) is a progressive, life-threatening condition characterised by pulmonary vascular resistance and associated with severe outcomes. According to the European Society of Cardiology and European Respiratory Society (ESC/ERS) guidelines, the risk assessment and prognosis of PAH are reliant on multiple investigations, including cardiac magnetic resonance imaging (MRI) and N-terminal prohormone brain natriuretic peptide (NT-proBNP). The overall aim of this body of work was to investigate the clinical benefit of cardiac MRI including artificial intelligence (AI) approaches, and NT-proBNP to assess the right atrium (RA) and right ventricle (RV) for severity assessment and prognosis in PAH. A cardiac MRI-based automated AI analysis of the RA and RV was developed, and the AI failure rate of the model was tested. Repeatability and agreement of contours of automated cardiac MRI analysis of the RA were evaluated. The prognostic significance of AI RV and AI RA area and their utility to risk stratify patients with PAH have been identified and compared with one another. The importance and relationship between automated cardiac MRI and NT-proBNP in PAH have been highlighted. The work has shown that cardiac MRI RV and RA area measurements can be fully automated using AI with a very low failure rate. The variability of AI-derived RA area measurements was lower than manual measurements in a scan-rescan cohort. Manual and automated RA area measurements moderately correlate with invasive haemodynamics. NT-proBNP showed a moderate correlation when compared to automated RV function. Measures of RV function and RA area have prognostic value; nonetheless, only measures of RV function but not ESC/ERS RA area thresholds identify patients at low-risk of 1-year mortality. Finally, the need for further work exploring larger cohorts with NT-proBNP and cardiac MRI measurements to investigate the incremental value of different approaches when assessing the right ventricle has been recommended.38 0