Novel Imaging and Spectroscopy Technique Unveiled

Researchers have demonstrated a new imaging technique that combines nuclear imaging using gamma-ray cameras and Magnetic Resonance Imaging (MRI).

The research was published online on September 29, 2016, in the journal Nature. The combined imaging and spectroscopic modality uses the spatial information encoded into the spin orientations of very small quantities of a polarized radioactive tracer. The Polarized Nuclear Imaging (PNI) modality uses both Radio Frequency (RF) and magnetic-field gradients and obtains imaging information by detecting gamma rays. The modality requires only a single gamma ray detector, instead of a gamma ray camera.

The researchers from the University of Virginia (UVA; Charlottesville, VA, USA) produced images and spectra from a glass cell containing only a tiny quantity of 131mXe, a metastable isomer. The researchers polarized the isomer using a laser technique called spin-exchange optical pumping. The glass cell contained approximately 4 × 1013 atoms (around 1 millicurie) of the isomer.

According to the researchers, if they had filled the cell with water and used conventional MRI imaging, then they would have needed 1024 water molecules, billions of molecules more than the radioactive tracer. This new highly sensitivity technique could lead to a new class of nuclear medicine tracers and expanded applications for magnetic resonance imaging. The tiny quantity of radioactive tracer needed for the new imaging technique means that it would result in a much smaller radiation dose for imaging subjects.

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