Instantaneous digital subtraction angiography for neurovascular applications

Emory University, Atlanta GA

Investigators

Abstract

__________________________________________________________________________________ Abstract Due to intracranial vascular malformations, such as aneurysm, or stenosis, thrombosis and embolism, cerebrovascular disease (CVD) may manifest as ischemic/hemorrhagic stroke. The CVD ranks 5th in major causes of death and disability in the US and has claimed 160,264 lives in 2020, highlighting more investment in basic and clinical research to address the unmet needs for CVD prevention, diagnosis, prognosis and therapeutic intervention. As a minimum invasive procedure, the intra-arterial digital subtraction angiography (IA-DSA) provides hemodynamic information on the fly for intervention, enabling critical decision-making in percutaneous angiography guided procedures. Thus far, IA-DSA has been the gold-standard for CVD diagnosis and therapeutical interventions, though a few new techniques, e.g., CT/MRI angiography, are finding their clinical utilities. However, an intravenous DSA (IV-DSA) is still clinically desirable in recognition of the risk of complications associated with IA-DSA (Challenge I). Also, there exist motion artifacts (Challenge II) induced by vascular pulsation or the patient’s involuntary motion and nephropathy (Challenge III) induced by small, iodinated contrast agent molecules that are cleared from the body via renal excretion. Recently, X-ray phase-sensitive imaging (PSI) has emerged as a novel modality and is reaching human scale for clinical applications. The dark-field (D-F) contrast generated by microstructures in X-ray PSI can be substantially larger than the conventional attenuation contrast that has been used for imaging since X-ray’s discovery. Super-paramagnetic iron oxide nanorods have been proposed and implemented for theranostic applications, including T2-weighted MRI by shortening the time of spin-lattice relaxation. To overcome the above three mentioned clinical challenges in IA-DSA, we propose to investigate the feasibility of instantaneous DSA (iDSA), which is a synergetic combination of X-ray D-F imaging and SPIO nanorods, for intravenous CVD screening, diagnosis and therapeutic intervention with sufficient contrast sensitivity and no motion artifacts. Towards the long-term goal of establishing the iDSA as a standalone modality, we specify the following two Aims in the proposed project: (1) Optimization of SPIO nanorod’s dimension to maximize the D-F signal for iDSA via simulation study, (2a) Phantom study to optimize the imaging method and demonstrate the relation between D-F signal and iron concentration in SPIO nanorods, and (2b) Animal study to optimize the imaging method and assess its potential for iDSA with no motion artifacts.