The overall goals of this project are to develop and validate robust, <20-minute MRI strategies for pre-procedural high-resolution imaging of the great vessels, free from the need for contrast agents or electrocardiographic (ECG) gating. The use of pre-procedural CT angiography (CTA) and contrast-enhanced MRA (CEMRA) provides critical structural information that is essential for optimal patient outcomes. However, most patients undergoing transcatheter aortic valve replacement (TAVR) or pulmonary vein isolation (PVI) are elderly, and many suffer from multi-system vascular disorders or other co-morbidities. The high incidence of renal dysfunction in these patients raises serious concerns for giving contrast agents. With severe renal dysfunction, CTA is contraindicated due to the risk of contrast-induced nephropathy, while CEMRA is contraindicated due to the risks of nephrogenic systemic fibrosis and tissue-deposition of gadolinium more generally. We hypothesize that next- generation optimized imaging strategies (OIS) based on single-shot radial quiescent-interval slice-selective (QISS) MRA will provide a high-impact benefit to patient care by enabling the creation of artifact-free angiographic images with near isotropic spatial resolution, without the need for contrast agents. Moreover, each OIS will be highly efficient with a total exam time <20 minutes. Both breath-hold and free-breathing strategies will be explored. Technical enhancements will include: (1) undersampled single-shot radial acquisitions to reduce sensitivity to cardiac arrhythmias, (2) iterative reconstruction using non-Cartesian SENSE or compressed sensing to improve the image quality of highly-undersampled radial scans, (3) navigator-gated 2D acquisitions to eliminate the need for breath-holding, (4) retrospective motion correction using affine or nonrigid transformations so as to facilitate the creation of maximum intensity projections and volume renderings, (5) strategic application of disk-shaped pseudocontinuous arterial spin labeling (PCASL) regions to enable the creation of vessel-selective angiograms; (6) M-mode gating to improve the robustness of cardiac synchronization while eliminating the need for electrocardiographic (ECG) leads. (7) simultaneous multi-slice methods to facilitate efficient coverage of large vascular regions and minimize the likelihood of image misregistration for breath-hold exams; (8) frequency-swept acquisitions to mitigate banding artifacts. This proposal entails an initial 3-year technical development phase followed by a 2-year research trial to validate the optimized imaging strategies.
The specific aims for our five-year proposal are as follows: 1. To develop <20-minute optimized imaging strategies for near isotropic imaging of the great vessels, free from the need for contrast agents or ECG gating. 2. To perform a single-center research trial in patients scheduled for TAVR or PVI, in order to validate the performance of breath-hold and free-breathing OIS in comparison with pre-procedural CTA.
Over the last decade, percutaneous cardiovascular interventions have become an increasingly attractive alternative to surgery in high-risk patients. For instance, transcatheter aortic valve replacement (TAVR) is used to treat patients with severe symptomatic aortic stenosis who have an unacceptable surgical risk, or in whom there are technical concerns such as the presence of a porcelain aorta. Percutaneous pulmonary vein isolation (PVI) has proven highly effective for patients with atrial fibrillation (AF) who fail to respond adequately to medical therapy. There has been extraordinary growth in the utilization of these minimally invasive procedures over the last few years, driven by compelling evidence of improved patient outcomes and cost-effectiveness. The use of pre-procedural CT angiography (CTA) and contrast-enhanced MRA (CEMRA) provides critical planning information that is essential for optimal patient outcomes. However, most patients undergoing TAVR or PVI are elderly, and many suffer from multi-system vascular disorders or other co-morbidities. The high incidence of renal dysfunction in these patients raises serious concerns for giving contrast agents. The overall goals of this project are to develop and validate robust, <20-minute MRI strategies for pre-procedural high- resolution imaging of the great vessels, free from the need for contrast agents or ECG gating. The capability to safely and reliably evaluate the great vessels irrespective of the presence of renal functional impairment, cardiac arrhythmia or breath-hold ability will help to ensure that patients have the best possible outcome from their procedures.
|Shen, Daming; Edelman, Robert R; Robinson, Joshua D et al. (2018) Single-Shot Coronary Quiescent-Interval Slice-Selective Magnetic Resonance Angiography Using Compressed Sensing: A Feasibility Study in Patients With Congenital Heart Disease. J Comput Assist Tomogr 42:739-746|
|Edelman, Robert R; Serhal, Ali; Pursnani, Amit et al. (2018) Cardiovascular cine imaging and flow evaluation using Fast Interrupted Steady-State (FISS) magnetic resonance. J Cardiovasc Magn Reson 20:12|