PT - JOURNAL ARTICLE AU - Guillem Pratx AU - Kai Chen AU - Conroy Sun AU - Marian Axente AU - Laura Sasportas AU - Colin Carpenter AU - Lei Xing TI - High-Resolution Radioluminescence Microscopy of <sup>18</sup>F-FDG Uptake by Reconstructing the β-Ionization Track AID - 10.2967/jnumed.112.113365 DP - 2013 Oct 01 TA - Journal of Nuclear Medicine PG - 1841--1846 VI - 54 IP - 10 4099 - http://jnm.snmjournals.org/content/54/10/1841.short 4100 - http://jnm.snmjournals.org/content/54/10/1841.full SO - J Nucl Med2013 Oct 01; 54 AB - Radioluminescence microscopy is a new method for imaging radionuclide uptake by single live cells with a fluorescence microscope. Here, we report a particle-counting scheme that improves spatial resolution by overcoming the β-range limit. Methods: Short frames (10 μs−1 s) were acquired using a high-gain camera coupled to a microscope to capture individual ionization tracks. Optical reconstruction of the β-ionization track (ORBIT) was performed to localize individual β decays, which were aggregated into a composite image. The new approach was evaluated by imaging the uptake of 18F-FDG in nonconfluent breast cancer cells. Results: After image reconstruction, ORBIT resulted in better definition of individual cells. This effect was particularly noticeable in small clusters (2–4 cells), which occur naturally even for nonconfluent cell cultures. The annihilation and Bremsstrahlung photon background signal was markedly lower. Single-cell measurements of 18F-FDG uptake that were computed from ORBIT images more closely matched the uptake of the fluorescent glucose analog (Pearson correlation coefficient, 0.54 vs. 0.44, respectively). Conclusion: ORBIT can image the uptake of a radiotracer in living cells with spatial resolution better than the β range. In principle, ORBIT may also allow for greater quantitative accuracy because the decay rate is measured more directly, with no dependency on the β-particle energy.