27 Jan A multi-modality approach for enhancing 4D flow MRI via sparse representation
4D flow magnetic resonance imaging (MRI) allows for the in vivo acquisition of time-resolved three-dimensional (3D) blood flow, enabling the evaluation of hemodynamic quantities for cerebral aneurysms (CAs). However, the accuracy of flow-derived hemodynamic quantities such as pressure and wall shear stress (WSS) is affected by the limited spatial and temporal resolution and noise inherent to 4D flow MRI. This work evaluates and applies a multi-modality approach, named Multi-modality Sparse Representation (MSR), to enhance the blood flow measurements and the hemodynamic analysis with 4D flow MRI in cerebral aneurysms. Using a library of high-resolution velocity fields from patient-specific computational fluid dynamic simulations and in vitro particle tracking velocimetry measurements, the flow field of 4D flow MRI data is reconstructed as the sparse representation of the library. The method was evaluated with synthetic 4D flow MRI data in two cerebral aneurysms. The reconstruction enhanced the spatial resolution and velocity accuracy of the synthetic MRI data, leading to reliable pressure and wall shear stress (WSS) evaluation. The method was applied on in vivo 4D flow MRI data acquired in the same cerebral aneurysms. The reconstruction increased the velocity and WSS by 6-13% and 39-61%, respectively, suggesting the accuracy of these quantities was improved since the raw MRI data underestimated the velocity and WSS by 10-20% and 40-50%, respectively. The computed pressure fields from the reconstructed data were consistent with the observed flow structures. The results suggest that using the sparse-representation flow-reconstruction with in vivo 4D flow MRI enhances the blood flow measurement and hemodynamic analysis.
(a) The method of localized flow reconstruction with sparse representation. (b) Performance of the MSR is evaluated with synthetic 4D flow data of aneurysmal flow. (c) The MSR application is applied to in vivo 4D flow data in cerebral aneurysms.
The statistical distributions of velocity magnitudes, WSS, and pressure at all time points in the cardiac cycle from the in vivo 4D flow MRI data and the MSR-reconstructed data for the basilar tip aneurysm (a) and the internal carotid artery aneurysm (b). The median of the statistical distributions is represented using solid lines, while the shaded regions correspond to the range between the st and 3rd quartiles.
Data and source codes used in this study are available in the Purdue University Research Repository (Title: A multi-modality approach for enhancing 4D flow MRI via sparse representation. URL: https://purr.purdue.edu/publications/3872/1).
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