In vivo simultaneous imaging with ^99mTc and ¹⁸F using a Compton camera.

We have been developing a medical imaging technique using a Compton camera. This study evaluates the feasibility of clear imaging with Tc-99m and F-18 simultaneously, and demonstrates in vivo imaging with Tc-99m and/or F-18. We used a Compton camera with silicon and cadmium telluride (Si/CdTe) semiconductors. We estimated the imaging performance of the Compton camera for 141 keV and 511 keV gamma rays from Tc-99m and Na-22, respectively. Next, we simultaneously imaged Tc-99m and F-18 point sources to evaluate the cross-talk artifacts produced by a higher energy gamma-ray background. Then, in the in vivo experiments, three rats were injected with Tc-99m-dimercaptosuccinic acid and/or F-18-fluorodeoxyglucose and imaged. The Compton images were compared with PET images. The rats were euthanized, and the activities in their organs were measured using a well counter. The energy resolution and spatial resolution were measured for the sources. No apparent cross-talk artifacts were observed in the practical-activity ratio (Tc-99m:F-18 = 1:16). We succeeded in imaging the distributions of Tc-99m and F-18 simultaneously, and the results were consistent with the PET images and well counter measurements. Our Si/CdTe Compton camera can thus work as a multi-tracer imager, covering various SPECT and PET probes, with less cross-talk artifacts in comparison to the conventional Anger cameras using a collimator. Our findings suggest the possibility of human trials.