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Magnetic particle imaging (MPI) is a promising imaging technique for a variety of clinical and scientific applications ranging from angiography [1] to stem cell tracking [2]. The native 2D point spread function (PSF) presents two challenges: the PSF is anisotropic, and there is an obscuring image “haze” that reduces image contrast due to the long tails of the 2D PSF [3]. These effects are illustrated...
Magnetic Particle Imaging (mpi) is a promising new modality that images only a magnetic tracer, commonly super-paramagnetic iron oxide (spio) nanoparticles [1, 2]. During data acquisition information about the dc component of the native image is lost, and must be recovered using some a priori knowledge such as image continuity and positivity [3,4]. One method of recovery uses convex optimization techniques...
MPI shows great promise for safe angiography, blood pool, and perfusion imaging. MPI images have unprecedented contrast that enables unambiguous measurements of tracer quantity and location [1-4]. At present, pre-clinical MPI resolution does not compare with pre-clinical MRI and CT, which routinely achieve better than 100-micron resolution. MPI's low resolution is primarily due to limitations in MPI...
An MPI spectrometer [1-3] measures the harmonics generated when a nonlinear SPIO is excited by a sinusoidal field. The harmonic peak spectrum allows for comparing SPIOs spatial resolution, since the harmonics are related to the modulation transfer function of the MPI imaging PSF [4-5]. It is also powerful to directly measure the point-spread function (PSF) by using the x-space MPI image reconstruction...
The sensitivity of Magnetic Particle Imaging (MPI), at fewer than 1000 detectable iron-labeled cells, is already comparable to imaging techniques like nuclear medicine [1-2]. However, the true physical sensitivity limits in MPI have not yet been achieved. Importantly, the preamplifier stage of an MPI receiver chain must be optimized to achieve low noise figures (NF) for the reactive inductor sensors...
The predominant imaging techniques used for preclinical research currently include optical imaging, magnetic resonance imaging (MRI), and nuclear medicine [1]. While these techniques have widespread pre-clinical adoption, they face challenges such as signal attenuation with tissue depth, lack of quantitativeness, radiation dose, and poor image contrast. By imaging the nonlinear magnetism of iron oxide...
There are two classes MPI selection fields: Field Free Point (FFP) magnets and Field Free Line (FFL) magnets [1, 2, 3]. A FFL selection field has three distinct benefits over a FFP selection field, namely (a) improved spatial resolution, (b) improved speed, and (c) improved SNR which scales with the number of projections [4]. Spatial resolution improves because the FFL is isotropic and hence uses...
Previous work has explored the effects of nanoparticle relaxation from the system matrix and x-space reconstruction points of view [1-8]. Here we demonstrate how relaxation can be used to “colorize” an image based on relaxation mechanisms using x-space reconstruction [9] and a pixel-wise linear model.
Fig.1 shows preliminary simulation data of PSFs from the 1D EPI sequence and a multidimensional rhodonea rose sequence. It is observed that the PSF from the rhodonea rose pulse sequence has higher, more isotropic resolution than the EPI PSF. Reconstruction time for a 42 by 41 pixel slice was 3 seconds. Fig.2. shows the designed and constructed multi-channel transmit/receive coils, yielding an imaging...