Inventors

Shinji Motomura and Shuichi Enomoto (Multiple Molecular Imaging Research Laboratory)

Background

Molecular imaging offers key insights into disease processes by quantitative visualization of the biological information at the molecular and cellular levels. In particular, nuclear medical imaging modalities, which use radio-labeled molecular probes as the imaging agent, are suitable for human clinical application because of the deeper penetrating power of the gamma-ray signals, high sensitivity, and low toxicity. However, conventional gamma-ray imaging cameras including PET and SPECT can use only one molecular probe at a time, while recent life sciences research is showing that multiple factors of genetic and environmental factors are related in a complicated way to the pathogenesis. Thus, simultaneous imaging of multiple molecular probes is desired to untangle the complicated relationship between various factors and the pathogenesis.

Summary

RIKEN researchers have demonstrated the feasibility of semiconductor Compton cameras (GREI) for multiple molecular imaging in nuclear medicine. The Compton camera used in this work comprises two double-sided orthogonal-strip germanium detectors, and their excellent energy resolution enabled discrimination of the nuclides and accurate determination of the gamma-ray source distribution. Three radiopharmaceuticals of⁶⁵ZnCl₂,⁸⁵SrCl₂, and iodinated (¹³¹I) methylnorcholestenol were simultaneously injected into a living mouse, and both two- and three-dimensional images of each radiopharmaceutical were obtained by a fixed-angle imaging with a single Compton camera. Moreover, RIKEN has the Japanese registered patent and pending international patent for lowering the energy limit of GREI by adding a silicon detector.

Merits

• Simultaneous imaging of multiple radiopharmaceuticals including both PET and SPECT imaging agents
• Various radionulides can be used for radiolabeling, taking into account the timescale and the stability

Applications

• Early-stage diagnosis of cancer, diabetes mellitus, and other common diseases
• Monitoring of curative process, especially for transplant and regenerative medicine

References

• 1.Japanese Patent No.4486623, US Patent No.8076645, EP Patent No.2060932
• 2.Japanese Patent No.5371086, US Patent No.8227759
• 3.Japanese Patent No.5582370