Magnetic particle imaging (MPI) using the nonlinear interaction between internally administered magnetic nanoparticles
(MNPs) and electromagnetic waves irradiated from outside of the body has attracted attention for the early diagnosis of
diseases such as cancer. In MPI, the local magnetic field distribution is scanned, and the magnetization signal from
MNPs inside an object region is detected. However, the signal sensitivity and image resolution are degraded by
interference from the magnetization signal generated by MNPs that exist outside of the desired region, owing to
nonlinear responses. Earlier, we proposed an image reconstruction method for suppressing the interference component
while emphasizing the signal component using the property of the higher harmonic components generated by the MNPs.
However, edge areas in the reconstructed image were emphasized excessively owing to the high-pass-filter effect of this
method. Here, we propose a new method based on correlation information between the observed signal and a system
function. We performed a numerical analysis and found that, although the image was somewhat blurred, the detection
sensitivity can clearly be improved without the inverse-matrix operation used in conventional image reconstruction.
Magnetic particle imaging (MPI) based on the nonlinear interaction between internally administered magnetic
nanoparticles and electromagnetic waves that externally irradiate the body has attracted attention for the early diagnosis
of diseases such as cancer. In MPI, the local magnetic field distribution is scanned, and the magnetization signals are
detected from the magnetic nanoparticles inside a target region. However, interference of the magnetization signals
generated from the magnetic nanoparticles outside a target region due to nonlinear responses results in the degradation of
image resolution. In this study, we clearly show that the degradation of image resolution is a result of the presence of
even harmonics in the magnetization response of magnetic nanoparticles. We propose a new image reconstruction
method for reducing these even harmonics and a correction method for suppressing the interference of the signals. This is
achieved by taking into account the difference between the saturated waveform of the magnetization signal detected from
the magnetic nanoparticles outside a target region and that detected from the magnetic nanoparticles inside a target
region. In this study, we perform numerical analyses to prove that the image resolution in the molecular imaging
technique can be improved by using our proposed image reconstruction method, which is based on the abovementioned
ideas. Furthermore, a fundamental system is constructed and the numerical analyses are experimentally validated by
using magnetic nanoparticles with a diameter of ~20 nm.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.