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MRI detection of single particles for cellular imaging
Erik M Shapiro1, Stanko Skrtic, Kathryn Sharer
1Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA. shapiroe@ninds.nih.gov
Summary
Magnetic resonance imaging (MRI) can now detect single micrometer-sized iron oxide particles (MPIOs) in cells and embryos. This breakthrough advances cellular imaging by enabling detection of individual particles, not millions.
Area of Science:
- Biomedical Imaging
- Nanotechnology
- Cell Biology
Background:
- Magnetic resonance imaging (MRI) is increasingly used for molecular and cellular imaging.
- Current methods rely on ultrasmall iron oxide particles, requiring millions per cell for detection.
- A need exists for more sensitive particle detection methods in cellular imaging.
Purpose of the Study:
- To investigate the feasibility of detecting single micrometer-sized iron oxide particles (MPIOs) using MRI.
- To assess the impact of MRI resolution and particle size on MPIO detectability.
- To demonstrate the utility of single MPIO detection in cellular and embryonic imaging.
Main Methods:
- MRI experiments were conducted on MPIOs in agarose, cultured cells, and mouse embryos.
- Particle sizes ranged from 0.76 to 1.63 micrometers.
- Fluorescent MPIOs were used for correlative microscopy in cells and embryos.
Main Results:
- Single MPIOs were detectable by MRI in vitro, in cultured cells, and in mouse embryos.
- T(2)* effects from single MPIOs were detected at 50-microm resolution, with significant signals at resolutions as low as 200 microm.
- Single fluorescent MPIOs in single cells were confirmed by both MRI and fluorescence microscopy.
- Single MPIOs injected into mouse embryos were detectable at embryonic day 11.5, persisting through cell divisions.
Conclusions:
- MRI can successfully detect single micrometer-sized iron oxide particles.
- Single-particle detection via MRI offers a novel approach for advanced cellular imaging.
- This technique holds promise for tracking cells and understanding biological processes at the single-particle level.