TY - JOUR
T1 - Transverse MNP Signal-Based Isotropic Imaging for Magnetic Particle Imaging
AU - Li, Lei
AU - Liao, Yidong
AU - Wang, Qibin
AU - Zhang, Zhonghao
AU - Ge, Dawei
AU - Hu, Jiawei
AU - He, Ning
AU - Liu, Yanjun
AU - Xu, Chenxiao
AU - Gao, Yunpeng
AU - Guo, Pengyue
AU - Hui, Hui
AU - Feng, Xin
AU - Zhu, Shouping
AU - Tian, Jie
N1 - Publisher Copyright:
© 1963-2012 IEEE.
PY - 2024
Y1 - 2024
N2 - Magnetic particle imaging (MPI) is a tracer-based imaging modality known for its high sensitivity and temporal resolution. It makes the quantitative visualization of the concentration and spatial location of magnetic nanoparticles (MNPs) possible. The x-space method is widely used in MPI for high-speed image reconstruction. In this method, the received signal is mapped directly onto the corresponding spatial position. However, the anisotropic 2-D point spread function (PSF) in the x-space method introduces artifacts and blur in the reconstructed images. In this study, an isotropic MPI method, transverse MNP signal-based isotropic imaging (TSI), was developed. It makes isotropic imaging possible in 2-D unidirectional Cartesian MPI. Unlike conventional methods that rely on MNP signals registered from the same direction as the excitation, TSI only utilizes MNP signals received perpendicular to the excitation direction. In TSI, the velocity of the time domain signal is first normalized to obtain a 'raw-image.' The raw-image is then integrated, differentiated, and added to generate an isotropic MPI image. Because all the operations in TSI are analytical, it preserves the real-time imaging characteristics of the x-space while isotropic imaging is performed. The PSF of TSI was calculated through analytical derivation and the resolution isotropy was validated through simulation and imaging experiments on an in-house-built MPI system. The simulation and experimental results demonstrate that, by improving the isotropy, TSI achieves an approximately 2.5- × increase in resolution in the nonexcitation direction compared with the conventional x-space method. The proposed TSI algorithm does not increase hardware complexity and requires only half the scanning time of the previously proposed multichannel method. In addition, the transverse MNP signal used in TSI is geometrically decoupled from the excitation magnetic field, eliminating the need for a special compensation design for the receiving coils. This shows promise for future MPI designs with flexible surface coils.
AB - Magnetic particle imaging (MPI) is a tracer-based imaging modality known for its high sensitivity and temporal resolution. It makes the quantitative visualization of the concentration and spatial location of magnetic nanoparticles (MNPs) possible. The x-space method is widely used in MPI for high-speed image reconstruction. In this method, the received signal is mapped directly onto the corresponding spatial position. However, the anisotropic 2-D point spread function (PSF) in the x-space method introduces artifacts and blur in the reconstructed images. In this study, an isotropic MPI method, transverse MNP signal-based isotropic imaging (TSI), was developed. It makes isotropic imaging possible in 2-D unidirectional Cartesian MPI. Unlike conventional methods that rely on MNP signals registered from the same direction as the excitation, TSI only utilizes MNP signals received perpendicular to the excitation direction. In TSI, the velocity of the time domain signal is first normalized to obtain a 'raw-image.' The raw-image is then integrated, differentiated, and added to generate an isotropic MPI image. Because all the operations in TSI are analytical, it preserves the real-time imaging characteristics of the x-space while isotropic imaging is performed. The PSF of TSI was calculated through analytical derivation and the resolution isotropy was validated through simulation and imaging experiments on an in-house-built MPI system. The simulation and experimental results demonstrate that, by improving the isotropy, TSI achieves an approximately 2.5- × increase in resolution in the nonexcitation direction compared with the conventional x-space method. The proposed TSI algorithm does not increase hardware complexity and requires only half the scanning time of the previously proposed multichannel method. In addition, the transverse MNP signal used in TSI is geometrically decoupled from the excitation magnetic field, eliminating the need for a special compensation design for the receiving coils. This shows promise for future MPI designs with flexible surface coils.
KW - Isotropic resolution
KW - magnetic particle imaging (MPI)
KW - reconstruction
KW - transverse magnetic nanoparticle (MNP) signal
UR - https://www.scopus.com/pages/publications/85179822127
U2 - 10.1109/TIM.2023.3341123
DO - 10.1109/TIM.2023.3341123
M3 - 文章
AN - SCOPUS:85179822127
SN - 0018-9456
VL - 73
SP - 1
EP - 13
JO - IEEE Transactions on Instrumentation and Measurement
JF - IEEE Transactions on Instrumentation and Measurement
M1 - 4501413
ER -