Multidimensional X-Space Magnetic Particle Imaging

Goodwill, Patrick; Conolly, Steven M.

doi:10.1109/tmi.2011.2125982

Cited by 257 publications

(325 citation statements)

References 24 publications

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“…For 1D excitation (used when realizing a Cartesian sampling scheme) the x-space approach leads to very good reconstruction results. However, the reconstruction of MPI data has not been shown to be feasible using x-space reconstruction techniques when acquisition is along Lissajous-type trajectories (Goodwill and Conolly 2011).…”

Section: Introductionmentioning

confidence: 99%

Hybrid system calibration for multidimensional magnetic particle imaging

et al. 2017

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Magnetic particle imaging visualizes the spatial distribution of superparamagnetic nanoparticles. Because of its key features of excellent sensitivity, high temporal and spatial resolution and biocompatibility of the tracer material it can be used in multiple medical imaging applications. The common reconstruction technique for Lissajous-type trajectories uses a system matrix that has to be previously acquired in a time-consuming calibration scan, leading to long downtimes of the scanning device. In this work, the system matrix is determined by a hybrid approach. Using the hybrid system matrix for reconstruction, the calibration downtime of the scanning device can be neglected. Furthermore, the signal to noise ratio of the hybrid system matrix is much higher, since the size of the required nanoparticle sample can be chosen independently of the desired voxel size. As the signal to noise ratio influences the reconstruction process, the resulting images have better resolution and are less affected by artefacts. Additionally, a new approach is introduced to address the background signal in image reconstruction. The common technique of subtraction of the background signal is replaced by Institute of Physics and Engineering in MedicineOriginal content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. 4 These authors contributed equally to this work. extending the system matrix with an entry that represents the background. It is shown that this approach reduces artefacts in the reconstructed images.

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Section: Introductionmentioning

confidence: 99%

Hybrid system calibration for multidimensional magnetic particle imaging

et al. 2017

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“…Here, we review the 1-D case; for the 3-D case, please see [12]. Under the adiabatic assumption that relaxation effects are negligible, the scalar magnetization of a SPIO in response to an applied field H(x, t) [A/m] obeys the Langevin equation for paramagnetism (1) where We now derive the adiabatic X-Space Image Reconstruction Equation by simply dividing the received signal by the instantaneous FFP velocity and scalar terms to obtain (4) where adiab (x s (t)) is the adiabatic x-space image.…”

Section: A Review Of Adiabatic X-space Theory In One Dimensionmentioning

confidence: 99%

“…The x-space image reconstruction algorithm is quick, robust, and produces no noise gain. The x-space theory was derived with three physical assumptions [11], [12].…”

Section: A Review Of Adiabatic X-space Theory In One Dimensionmentioning

confidence: 99%

“…Because relaxation temporally delays the received signal, we estimate that the peak signal is delayed by approximately half the relaxation time. Therefore, we modify the Non-Adiabatic X-Space Image Reconstruction Equation to read (12) Here, we perform velocity compensation with the FFP velocity temporally delayed by half the relaxation time. Below we show that this approximation performs well in both simulations and experiments.…”

Section: B Non-adiabatic X-space Theory In One Dimensionmentioning

confidence: 99%

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Relaxation in x-space Magnetic Particle Imaging

Croft

Goodwill

Ferguson

et al. 2012

Springer Proceedings in Physics

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Magnetic particle imaging (MPI) is a new imaging modality that noninvasively images the spatial distribution of superparamagnetic iron oxide nanoparticles (SPIOs). MPI has demonstrated high contrast and zero attenuation with depth, and MPI promises superior safety compared to current angiography methods, X-ray, computed tomography, and magnetic resonance imaging angiography. Nanoparticle relaxation can delay the SPIO magnetization, and in this work we investigate the open problem of the role relaxation plays in MPI scanning and its effect on the image. We begin by amending the x-space theory of MPI to include nanoparticle relaxation effects. We then validate the amended theory with experiments from a Berkeley x-space relaxometer and a Berkeley x-space projection MPI scanner. Our theory and experimental data indicate that relaxation reduces SNR and asymmetrically blurs the image in the scanning direction. While relaxation effects can have deleterious effects on the MPI scan, we show theoretically and experimentally that x-space reconstruction remains robust in the presence of relaxation. Furthermore, the role of relaxation in x-space theory provides guidance as we develop methods to minimize relaxation-induced blurring. This will be an important future area of research for the MPI community.

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“…1 MPI is very sensitive (∼100 nmol/voxel detection limit), has exquisite contrast as a tracer modality (no background signal), and is capable of real-time imaging. [2][3][4] In terms of applications, MPI has been proposed as an alternative angiographic imaging technique, especially for patients with chronic kidney disease (CKD) who cannot tolerate the iodine-and gadoliniumbased contrast agents used in CT and MR angiography. 5 Recent publications describing in vivo cell tracking have also demonstrated the significant potential of MPI as a molecular imaging technique.…”

Section: Introductionmentioning

confidence: 99%

Eddy current-shielded x-space relaxometer for sensitive magnetic nanoparticle characterization

Bauer

Hensley

Zheng

et al. 2016

Review of Scientific Instruments

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The development of magnetic particle imaging (MPI) has created a need for optimized magnetic nanoparticles. Magnetic particle relaxometry is an excellent tool for characterizing potential tracers for MPI. In this paper, we describe the design and construction of a high-throughput tabletop relaxometer that is able to make sensitive measurements of MPI tracers without the need for a dedicated shield room. Published by AIP Publishing. [http://dx

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Multidimensional X-Space Magnetic Particle Imaging

Cited by 257 publications

References 24 publications

Hybrid system calibration for multidimensional magnetic particle imaging

Hybrid system calibration for multidimensional magnetic particle imaging

Relaxation in x-space Magnetic Particle Imaging

Eddy current-shielded x-space relaxometer for sensitive magnetic nanoparticle characterization

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