AbstractLate gadolinium enhancement (LGEJ imaging is a widely used cardiovascular MRI technique. My work focused on developing new LGE MRI sequences to; identify plaque in the aortic vessel wall, to visualize areas of ventricular scar after myocardial infarction and pulmonary vein and atrial wall lesions after radiofrequency (RF) ablation for atrial fibrillation (AF). The double inversion recovery (DIR) sequence is traditionally used for vessel wall imaging. It however requires a Look Locker scan to choose the correct inversion time (TI) to achieve post-contrast blood suppression. The quadruple inversion recovery (QIR) sequence was later developed to suppress blood before and after contrast using identical imaging parameters. ECG-triggering was not required for the carotid arteries as there is adequate blood flow during the entire cardiac cycle to achieve sufficient blood exchange for blood suppression. I designed a new ECG-triggered QIR implementation for vessel wall imaging of the aorta which has variable flow during the cardiac cycle. I found it improved blood suppression, vessel wall sharpness and image quality scores compared to the un-triggered QIR implementation. The inversion recovery (IR) technique is the gold standard for imaging ventricular and atrial wall scar. It also requires a Look Locker scan to define the TI that suppresses normal myocardium in order to detect regions of scar. However, there is also often high IR blood signal that can hamper the detection of small sub-endocardial infarcts and scar size and transmurality measurements. I developed a novel dual-IR sequence that achieves suppression of normal myocardium and also reduces the blood signal. I found this improved blood suppression and inter-observer variability of scar size measurement and allowed imaging at an earlier time point compared to IR imaging for both ventricular and atrial wall scar.
For ventricular scar, I also found improved expert confidence and inter-observer variability for transmurality assessment.
|Date of Award
|Rene Botnar (Supervisor) & Tobias Schaeffter (Supervisor)