Visualization of Magnetic Nanofibers Using Magnetic Particle Imaging

Murase, Kenya; Mimura, Atsushi; Banura, Natsuo; Nishimoto, Kohei; Takata, Hiroshige

doi:10.4236/ojmi.2015.52009

Cited by 11 publications

(10 citation statements)

References 21 publications

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“…It is important to acquire system matrices of very high SNR when performing, for example, multicolor MPI (Murase et al 2015, Rahmer et al 2015. As the influence of single particle samples needs to be distinguishable, the noise level of the system matrices should be minimal.…”

Section: Discussionmentioning

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: Discussionmentioning

confidence: 99%

Hybrid system calibration for multidimensional magnetic particle imaging

et al. 2017

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“…The details of our MPI system are described in our previous paper [17]- [20]. In brief, a drive magnetic field was generated using an excitation coil (solenoid coil 100 mm in length, 80 mm in inner diameter, and 110 mm in outer diameter).…”

Section: System For Magnetic Particle Imagingmentioning

confidence: 99%

“…In phantom studies, samples with various iron concentrations of Resovist ® (0, 50, 100, 125, 250, and 500 mM) were prepared by putting Resovist ® into a cylindrical polyethylene tube 6 mm in diameter and 5 mm in length (100 μL) and were imaged using our MPI scanner [17]- [20]. These samples were also heated using our apparatus for magnetic hyperthermia [22] at 600 kHz and 3.1 kA/m, and the time course of the temperature was measured using an infrared thermometer (FLIR E4, FLIR Systems Inc., OR, USA) every 30 s during the first 2 min and every 1 min during the next 8 min after the beginning of magnetic hyperthermia.…”

Section: Phantom Experimentsmentioning

confidence: 99%

Usefulness of Magnetic Particle Imaging for Predicting the Therapeutic Effect of Magnetic Hyperthermia

Murase¹,

Aoki²,

Banura³

et al. 2015

OJMI

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Purpose: To investigate the usefulness of magnetic particle imaging (MPI) for predicting the therapeutic effect of magnetic hyperthermia (MH). Materials and Methods: First, we performed phantom experiments to investigate the relationship between the MPI value and the temperature rise of magnetic nanoparticles (MNPs) under an alternating magnetic field (AMF). The MPI value was defined as the pixel value of the transverse image reconstructed from the third-harmonic signals. Samples filled with various iron concentrations of MNPs (Resovist ®) were prepared and were imaged using our MPI scanner. These samples were also heated using the AMF, and the specific loss power (SLP) and volume-specific loss power (vSLP) were calculated from the initial slope of the time-dependent temperature rise. Second, we performed animal experiments using tumor-bearing mice, which were divided into untreated (n = 10) and treated groups (n = 20). The tumors in the treated group were injected with Resovist ® at an iron concentration of 250 mM (n = 10) or 500 mM (n = 10), and received MH for 20 min, during which the temperatures in the tumor and rectum were measured. The relative tumor volume growth (RTVG) was calculated from (V 15 − V 0)/V 0 , where V 0 and V 15 represented the tumor volume on day 0 and day 15 after MH, respectively. Results: In phantom experiments, the MPI value had significant correlations with the iron concentration of MNPs (r = 0.997), temperature rise (r = 0.981), and vSLP (r = 0.961). In animal experiments, the MPI value had significant correlations with the temperature rise in the tumor (r = 0.731) and RTVG (r = −0.687). Conclusion: Our preliminary results suggest that MPI is useful for predicting the therapeutic effect of MH.

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“…The details of our MPI system are described in our previous papers [14]- [19]. In brief, a drive magnetic field was generated using an excitation coil (solenoid coil 100 mm in length, 80 mm in inner diameter, and 110 mm in outer diameter).…”

Section: System For Magnetic Particle Imagingmentioning

confidence: 99%

Magnetic Particle Imaging for Magnetic Hyperthermia Treatment: Visualization and Quantification of the Intratumoral Distribution and Temporal Change of Magnetic Nanoparticles <i>in Vivo</i>

Kuboyabu¹,

Yabata²,

Aoki³

et al. 2016

OJMI

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Purpose: Magnetic hyperthermia treatment (MHT) is a strategy for cancer therapy using the temperature rise of magnetic nanoparticles (MNPs) under an alternating magnetic field (AMF). Recently, a new imaging method called magnetic particle imaging (MPI) has been introduced. MPI allows imaging of the spatial distribution of MNPs. The purpose of this study was to investigate the feasibility of visualizing and quantifying the intratumoral distribution and temporal change of MNPs and predicting the therapeutic effect of MHT using MPI. Materials and Methods: Colon-26 cells (1 × 10 6 cells) were implanted into the backs of eight-week-old male BALB/c mice. When the tumor volume reached approximately 100 mm 3 , mice were divided into untreated (n = 10) and treated groups (n = 27). The tumors in the treated group were directly injected with MNPs (Resovist ®) with iron concentrations of 500 mM (A, n = 9), 400 mM (B, n = 8), and 250 mM (C, n = 10), respectively, and MHT was performed using an AMF with a frequency of 600 kHz and a peak amplitude of 3.5 kA/m. The mice in the treated group were scanned using our MPI scanner immediately before, immediately after, 7 days, and 14 days after MHT. We drew a region of interest (ROI) on the tumor in the MPI image and calculated the average, maximum, and total MPI values and the number of pixels by taking the threshold value for extracting the contour as 40% of the maximum MPI value (pixel value) within the ROI. These parameters in the untreated group were taken as zero. We also measured the relative tumor volume growth (RTVG) defined by (V−V0)/V0, where V 0 and V are the tumor volumes immediately before and after MHT, respectively. Results:

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Visualization of Magnetic Nanofibers Using Magnetic Particle Imaging

Cited by 11 publications

References 21 publications

Hybrid system calibration for multidimensional magnetic particle imaging

Hybrid system calibration for multidimensional magnetic particle imaging

Usefulness of Magnetic Particle Imaging for Predicting the Therapeutic Effect of Magnetic Hyperthermia

Magnetic Particle Imaging for Magnetic Hyperthermia Treatment: Visualization and Quantification of the Intratumoral Distribution and Temporal Change of Magnetic Nanoparticles <i>in Vivo</i>

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Visualization of Magnetic Nanofibers Using Magnetic Particle Imaging

Cited by 11 publications

References 21 publications

Hybrid system calibration for multidimensional magnetic particle imaging

Hybrid system calibration for multidimensional magnetic particle imaging

Usefulness of Magnetic Particle Imaging for Predicting the Therapeutic Effect of Magnetic Hyperthermia

Magnetic Particle Imaging for Magnetic Hyperthermia Treatment: Visualization and Quantification of the Intratumoral Distribution and Temporal Change of Magnetic Nanoparticles &lt;i&gt;in Vivo&lt;/i&gt;

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Magnetic Particle Imaging for Magnetic Hyperthermia Treatment: Visualization and Quantification of the Intratumoral Distribution and Temporal Change of Magnetic Nanoparticles <i>in Vivo</i>