<i>In vivo</i>simultaneous imaging with^99mTc and¹⁸F using a Compton camera

Abstract

We have been developing a medical imaging technique using a Compton camera. This study evaluates the feasibility of clear imaging with ^99mTc and ¹⁸F simultaneously, and demonstrates in vivo imaging with ^99mTc and/or ¹⁸F. 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 ^99mTc and ²²Na, respectively. Next, we simultaneously imaged ^99mTc and ¹⁸F 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 ^99mTc-dimercaptosuccinic acid and/or ¹⁸F-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 (^99mTc:¹⁸F = 1:16). We succeeded in imaging the distributions of ^99mTc and ¹⁸F 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.