Radial MRI with variable echo times: reducing the orientation dependency of susceptibility artifacts of an MR-safe guidewire
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Guidewires are indispensable tools for intravascular MR-guided interventions. Recently, an MR-safe guidewire made from a glass-fiber/epoxy compound material with embedded iron particles was developed. The size of the induced susceptibility artifact, and thus the guidewire’s visibility, depends on its orientation against B 0. We present a radial acquisition scheme with variable echo times that aims to reduce the artifact’s orientation dependency.
Materials and methods
The radial acquisition scheme uses sine-squared modulated echo times depending on the physical direction of the spoke to balance the susceptibility artifact of the guidewire. The acquisition scheme was studied in simulations based on dipole fields and in phantom experiments for different orientations of the guidewire against B 0. The simulated and measured artifact widths were quantitatively compared.
Compared to acquisitions with non-variable echo times, the proposed acquisition scheme shows a reduced angular variability. For the two main orientations (i.e., parallel and perpendicular to B 0), the ratio of the artifact widths was reduced from about 2.2 (perpendicular vs. parallel) to about 1.2 with the variable echo time approach.
The reduction of the orientation dependency of the guidewire’s artifact via sine-squared varying echo times could be verified in simulations and measurements. The more balanced artifact allows for a better overall visibility of the guidewire.
KeywordsInterventional MRI Intravascular guidewires Susceptibility artifacts Radial acquisition Variable echo time
This work was supported by a Grant from the Deutsche Forschungsgemeinschaft (DFG) under the Grant Number BO 3025/2-2 and by a research contract with MaRVis Medical GmbH. Parts of this study were presented as an E-poster (abstract number: 3582) at the 24th Annual Meeting of the ISMRM in Singapore, 2016.
Katharina E. Schleicher: Project development, Data collection or management, Data analysis. Michael Bock: Project development, Data analysis. Klaus Düring: Project development. Stefan Kroboth: Data collection or management, Data analysis. Axel J. Krafft: Project development, Data collection or management, Data analysis.
Compliance with ethical standards
Conflict of interest
Katharina E. Schleicher: No potential conflict of interest. Michael Bock: No potential conflict of interest. Klaus Düring: Shareholder and CEO of MaRVis Medical GmbH and MaRVis Interventional GmbH. Stefan Kroboth: No potential conflict of interest. Axel J. Krafft: No potential conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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