Supramolecular Imaging Agents

MRI Contrast

The Hydroxide Free Ferrite (see below) is a nanometer scale particle that functions as a blood pool contrast agent for use in improving tissue distinction in MRI scanning. It causes a “black blood” effect (see below) on T2 imaging and bright on T1 imaging. By allowing the imaging of blood as a tissue Ferrite based MR Angiography provides greatly improved speed of image acquisition, improved signal to noise, and excellent definition at points of turbulence near plaques.

The black blood effect helps distinguish small nerves from small vessels in MR Neurography. In addition it completely blacks out the marrow of bone and makes it possible to create pure joint surface images revonstructed in 3D from any angle of view – this is expected to have a major impact on general orthopedic and spine imaging.

Spinel3Nanoscale ElectroCeramics – Fundamental Building Block of Biomedical Nanotechnology

Molecular Synthetics has pioneered a key fundamental building block of biomedical nanotechnology – the Hydroxide Free Ferrite. This is a spinel type crystal with Iron2+ and Iron3+ atoms imbedded in a dense rigid Oxygen matrix to create an extraodinarily stable electroceramic nanoparticle.

The particles are produced in the size range of around 10 nanometers, have powerful superparamagnetic properties, are coated with dextran, and are fully water soluble and biologically tolerable. The A and B sites may be substituted with other elements to achieve various desired effects.

The particles can be conjugated to targeting proteins and can be activated at a distance by magnetic or radiofrequency fields. They can carry stably included therapeutic elements, radionuclides for local brachytherapy, and for imaging. They remain dissolved when centrifuged, but become fully immobilized in polymerized hydrogels.

PrePostBBImgHydroxide Free Ferrites for Intravascular Use: Black Blood-Black Bone MR Image Contrast for Enhanced MR Imaging of Blood Vessels, Nerve, & Joints

The hydroxide free ferrites developed by Molecular Synthetics are a powerful and widely useful MR Imaging contrast agent acting in very different ways from the currently dominant gadolinium agents and achieving clinically important effects that current contrast agents cannot approach.

The black blood effect on T2 imaging and bright blood on T1 allow for dramatically improved MR angiography that is not affected by flow turbulence – a problem that limits the utility of “pulse sequence” MR Angiography in critical locations around plaques. Rapid high resolution MR vessel images will be useful for cardiovascular applications and for interventional angiography in the MR suite.

These agents also black out marrow and the vascularized portions of bone allowing for “pure joint images” from any angle of view. These will have important uses in orthopedics and neurosurgery.

Positron Emission Tomography (PET)

Imaging in Nuclear Medicine is based on capturing gamma rays and photons emitted from a radionuclide that has been placed in a location of medical interest.

In standard Single Photon Emission Tomography (SPECT) each nuclear disintegration sends out a single gamma ray in any direction. Collection of thousands of rays allows a low resolution image of the source to be created.

In Positron Emission Tomography (PET), upon disintegraion of the marker nuclide, each emitted positron travels through tissue losing energy until it meets an electron an undergoes a matter-antimatter annihilation reaction. This reaction sends out two photons in exactly opposite directions.

By “coincidence detection” the PET machine can determine a line along which the annihilation took place. As it collects hundreds of these, it can precisely locate the source, potentially providing a higher resolution image. However, the annihilation takes place up to a centimeter from the site at which the isotope originally disintegrated. MSI has developed a ferrite based PET carrier in which the density of the ferrite causes the annihilation to take place closer to the disintegration, improving spatial resolution by up to ten times. These can also be prepared as long half-life PET emitters allowing several days for distribution and imaging.

positronPositron Emitting Ferrites: Controlled Design to Achieve an Order of Magnitude Improvement in Image Spatial Resolution By Modulation of Matter-AntiMatter Reactions

The new field of molecular imaging requires highly detectable imaging labels with very high spatial resolution. By delivering positron emitting nuclides inside a targetable ferrite spinel crystal, MSI has greatly improved the spatial resolution of PET imaging. The distance of travel of a positron prior to annihilation greatly degrades spatial resolution. However that distance is dependent on the density of the medium through which the positron travels. Ferrites have twelve times the density of water, so annihilations take place ten times closer to the original disintegration at the molecular target site.

Molecular Imaging

An important new frontier in medical imaging is the design of targeted imaging labels that locate particular tissues or pathologies of interest. A typical agent (such as PET, see below) would, for instance carry a targeting protein that locates a type of cancer attached to radioisotope emitting particle that is detectable by medical imaging.

MSI ferrites can be modified to incorporate varying concentrations of imageable emitters. These particles are coated with biopolymers and can be conjugated to targeting proteins.

positronPositron Emitting Ferrites: Controlled Design to Achieve an Order of Magnitude Improvement in Image Spatial Resolution By Modulation of Matter-AntiMatter Reactions

The new field of molecular imaging requires highly detectable imaging labels with very high spatial resolution. By delivering positron emitting nuclides inside a targetable ferrite spinel crystal, MSI has greatly improved the spatial resolution of PET imaging. The distance of travel of a positron prior to annihilation greatly degrades spatial resolution. However that distance is dependent on the density of the medium through which the positron travels. Ferrites have twelve times the density of water, so annihilations take place ten times closer to the original disintegration at the molecular target site.