Table 2.
Summary of recent studies investigating the use of magnetic particle imaging (MPI) for imaging and detecting brain diseases
| Imaged models | Tracers | Scanner (mode*) | Findings | References |
|---|---|---|---|---|
| Xenograft tumor-in-situ glioma mice | Multimodality nanoparticles | MOMENTUM preclinical scanner (FFP, X-space) | MPI signals in brain tissue can increase 17.1 times after injection and MPI signals can be observed with rich blood supply | [26] |
| Xenograft tumor-in-situ glioma mice | FeCo@C | MOMENTUM preclinical scanner (FFP, X-space) | FeCo@C provides an MPI signal intensity that is 6-time and 15-time higher than the signals from VivoTrax and Feraheme, respectively | [48] |
| Xenograft tumor-in-situ glioma mice | Nanoparticles-covered the membrane of glioblastoma cells | MOMENTUM preclinical scanner (FFP, X-space) | MPI signal does not decay with tissue depth and shows excellent sensitivity for thousands of cells | [66] |
| Brain cancer xenografts | Lactoferrin-functionalized nanoparticles | MOMENTUM preclinical scanner (FFP, X-space) | The agent can detect 1.1 ng of iron (SNR was about 3.9). Lactoferrin coupling and external magnet can improve the tumor localization | [70] |
| C6 brain glioma cells in vitro | Lactoferrin-functionalized nanoparticles | Custom-built magnetic particle spectrometer | Nanoparticles with Lactoferrin have increased 5 times signal intensity compared to non-targeted particles | [87] |
| Neural progenitor cells in rat | Resovist | Custom-built MPI systems (FFL, X-space) | The detection limit is 200 cells (5.4 ng Fe) in vitro, and in vivo monitoring of human neural graft clearance is over 87 d in rat brain | [33] |
| Cerebral perfusion in healthy mice | Perimag | Dedicated surface coil for mice (FFP, system matrix) | MPI can detect tracer samples containing only 896 pg iron (about 69 cells), and even small vessels (150 µm diameter) and anatomical structures | [68] |
| Ischemic stroke model in mice | LS-008 |
Bruker preclinical System (FFP, system matrix) |
MPI can be used for real time detection of perfusion deficits associated with ischemic stroke | [60] |
| Intracranial hemorrhage model in mice | Perimag and Synomag-D | Bruker preclinical system (FFP, system matrix) | Multi-contrast MPI can differentiate clotted blood from active bleeding. The bleed can be detected in 3 min, and the quantitative range is 0.003 – 0.06 μl/s | [61] |
| Healthy rhesus macaque | Mag3200 |
Hand-held MPI detector |
The detector has a detection limit of about 125 ng Fe and can in vivo measure cerebral particle concentration changes | [88] |
| Stroke phantom | Perimag | Novel MPI head scanner (FFP, system matrix) | A system can achieve a sensitivity limit of 14.7 ng Fe/ml at a frame rate of 2 Hz and a spatial resolution of 5 mm | [56] |
| Hypercapnic model in rat | SPIONs with a 25 nm core and a polyethylene glycol carboxyl coating | Single-sided detector | MPI could measure CBV changes during hypercapnia with a CNR of 50 | [57] |
| Hypercapnia model in rat | Synomag-D | Home-built rodent scanner (FFL, system matrix) | The average CNR of CBV in fMPI was approximately 2 – 6 times higher than that in fMRI | [62] |
*Mode includes scanning mode (FFP or FFL) and image reconstruction method (system matrix or X-space reconstruction methods) of the scanner
FFL field-free line, FFP field-free point, SNR signal-to-noise ratio, CNR contrast-to-noise ratio, fMPI functional magnetic particle imaging, fMRI functional magnetic resonance imaging, CBV cerebral blood volum