Friday, April 19, 2024
4/19/2024
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.
HHS’ Tracking Accountability in Government Grants System (TAGGS) website provides access to detailed descriptions of grants, loans, aggregated direct payments and other types of financial assistance awarded by the HHS Operating Divisions (OPDIVs) and the Office of the Secretary Staff Divisions (STAFFDIVs).
