Cerenkov luminescence microscopy: A novel approach for high-resolution radiotracer imaging.

This study introduces a novel imaging system utilizing Cerenkov luminescence microscopy (CLM) to visualize the activity of radioactive tracers in 3D tumor spheroids. The system integrates an EMCCD camera, a microscope objective, and a precise sample positioning setup, enabling the high-resolution detection of Cerenkov light emission from radiotracers in a light-tight environment. The characteristics of the new CLM system have been tested on glioblastoma multiforme (GLM) spheroids, subjected or not to X-ray radiotherapy. The system effectively differentiated irradiated from non-irradiated spheroids by detecting distinct variations in signal intensity, which were further validated through comparison with autoradiography and quantitative activity measurements. This demonstrates the system's ability to provide highly sensitive imaging of radiolabeled biological samples. The method offers new possibilities for studying radiopharmaceutical distribution and metabolic processes at the cellular level, making it a valuable tool for advancing both diagnostic and therapeutic radiopharmaceutical development, as well as for evaluating treatment efficacy.