Magnetic Particle Imaging – Momentum High Resolution Molecular Imaging System

Magnetic Particle Imaging (MPI) is a new ultrasensitive high resolution molecular imaging technique suited to researchers working in the field of preclinical imaging. It is able to unambiguously detect iron oxide tracer at nanomolar concentrations anywhere in the body and the workflow is no more difficult to use than optical imaging.

According to the International Workshop on Magnetic Particle Imaging:

MPI is the most promising emerging imaging technology in the last 20 years and is expected to change the landscape of modern medical imaging and in vivo translational research.”

MPI is the perfect complement to other imaging modalities such as PET, optical and MRI. Furthermore, it holds fantastic potential for high resolution, sensitive quantitative imaging.

How Does MPI Work?

A “sensitive point” is generated using powerful magnets. This point is scanned across an animal subject. The iron oxide tracer agent nanoparticles that pass through the point generate a signal. This shows how the tissue functions.

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MPI has the added advantage that is able to produce clear images with excellent contrast regardless of signal depth. This means that it can be used to investigate any part of the body, on subjects of any size.

MPI SPIO Tracers

MPI uses custom tracers such as single core SPIO (super-paramagnetic iron oxide) nanoparticles that are within the range 20-25nm. The sensitivity is such that MPI can detect less than 100 tagged SPIO cells and these can be tracked anywhere in the body of the subject.

Applications

MPI complements other imaging modalities and enables:

  • Longer term monitoring of functional events thanks to long terms monitoring
  • Quantitation without any tissue attenuation
  • Potential clinical translation

 

MPI can be used for:

  • Longitudinal cell tracking
  • Blood Pool Imaging
  • Cancer and tumour imaging – oncology
  • Angiography
  • Vascular function
  • Stem cell, immune cell and cell tracking
  • Multi-colour MPI
  • Theranostic imaging
  • Perfusion
  • Functional nanoparticles
  • Image guided heating

How Does Magnetic Particle Imaging Work

MPI is a new imaging technique suited to preclinical imaging. It can directly detect iron oxide nanoparticle tracers using time varying magnetic fields. These tracers are introduced into the body and a positive signal from the particles has the same resolution and sensitivity regardless of depth.  As a result, MPI images provide excellent contract and sensitivity giving you an unprecedented view of what is happening, or how your therapy is affecting the host.

Magnetic Nanoparticles Align with an Applied Magnetic Field

Under ambient conditions, the iron oxide nanoparticles will be randomly oriented and their magnetisation said to be unsaturated. When a magnetic field is applied, the nanoparticles align and their magnetisation becomes saturated and reaches a maximum.

Controlling magnetic nanoparticles for Magnetic Particle Imaging

Producing a Field Free Point (FFP) with a Strong Magnetic Field Gradient

By opposing two strong magnets a strong magnetic field gradient is induced a special magnetic field where the nanoparticles will become unsaturated as they pass through this position; the Field Free Point or FFP. Only nanoparticles passing through this point will produce a signal.

Creating a field free poit in Magnetic Particle Imaging

Producing a Signal by Rapidly Moving the FFP

By rapidly moving the FFP through the body , the SPIO nanoparticles passing through the FFP flip from an unsaturated negative value to a saturated positive value. This change in magnetic state induces a signal in a receive coil. By controlling the position of the FFP, the signal at this specific point can be assigned and hence an MPI image produced.

Advantages of MPI over Other Imaging Modalities

Functional Imaging

Anatomical Imaging

MPIPETOpticalMRICT
Deep tissue imagingYesYesYesYes
QuantitativeYesYesYes
<100 cell sensitivity at any depth, key for cell trackingYesYes
Vascular, functional and cell based technologiesYesYes
Translatable to the clinicYesYesYesYes
Exquisite resolution ( <=1mm )YesYesYes
Long term tracer stabilityYesYesYes

Specifications

FeatureSpecification
Spatial resolution
Scanning times:
Projection mode
Tomographic mode

<10sec/image
5-15min/image
Reconstruction time<5min
Sensitivity10ng Fe in <5min
FOV mouse40 x 120mm

Other key features include:

  • Self-shielded architecture for flexible siting
  • Imaging bore
    • >=40 mm (Mouse)
    • >=60 mm (Rat)- Optional & upgradable when available
  • Gas anesthesia port
  • High performance control computer
  • 24-inch, high-resolution flat screen monitor
  • 8” panel touch screen display for animal handling
  • Acquisition software with intuitive subject set-up, acquisition, data viewing and DICOM export

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