Ultrahigh-resolution Cerenkov-light imaging system for positron radionuclides: potential applications and limitations

Ann Nucl Med. 2014 Dec;28(10):961-9. doi: 10.1007/s12149-014-0892-z. Epub 2014 Aug 8.

Abstract

Objective: Cerenkov-light imaging provides inherently high resolution because the light is emitted near the positron radionuclide. However, the magnitude for the high spatial resolution of Cerenkov-light imaging is unclear. Its potential molecular imaging applications also remain unclear. We developed an ultrahigh-resolution Cerenkov-light imaging system, measured its spatial resolution, and explored its applications to molecular imaging research.

Methods: Our Cerenkov-light imaging system consists of a high-sensitivity charged-coupled device camera (Hamamatsu Photonics ORCA2-ER) and a bright lens (Xenon 0.95/25). An extension ring was inserted between them to magnify the subject. A ~100-μm-diameter (22)Na point source was made and imaged by the system. For applications of Cerenkov-light imaging, we conducted (18)F-FDG administered in vivo, ex vivo whole brain, and sliced brain imaging of rats.

Results: We obtained spatial resolution of ~220 μm for a (22)Na point source with our developed imaging system. The (18)F-FDG rat head images showed high light intensity in the eyes for the Cerenkov-light images, although there was no accumulation in these parts in the PET images. The sliced rat brain showed much higher spatial resolution for the Cerenkov-light images compared with CdWO4 scintillator-based autoradiography, although some contrast decrease was observed for them.

Conclusion: Even though the Cerenkov-light images showed ultrahigh resolution of ~220 μm, their distribution and contrast were sometimes different from the actual positron accumulation in the subjects. Care must be taken when evaluating positron distribution from Cerenkov-light images. However, the ultrahigh resolution of Cerenkov-light imaging will be useful for transparent subjects including phantom studies.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autoradiography
  • Brain / diagnostic imaging
  • Fluorodeoxyglucose F18
  • Molecular Imaging / instrumentation
  • Molecular Imaging / methods*
  • Phantoms, Imaging
  • Radioisotopes
  • Radionuclide Imaging / instrumentation
  • Radionuclide Imaging / methods*
  • Radiopharmaceuticals
  • Rats, Nude
  • Skin Neoplasms / diagnostic imaging
  • Sodium Radioisotopes

Substances

  • Radioisotopes
  • Radiopharmaceuticals
  • Sodium Radioisotopes
  • Fluorodeoxyglucose F18