Imaging of ^99mTc-DMSA and ¹⁸F-FDG in humans using a Si/CdTe Compton camera

The Compton camera can simultaneously acquire images of multiple isotopes injected in a body; therefore, it has the potential to introduce a new subfield in the field of biomedical imaging applications. The objective of this study is to assess the ability of a prototype semiconductor-based silicon/cadmium telluride (Si/CdTe) Compton camera to simultaneously image the distributions of technetium (^99mTc)-dimercaptosuccinic acid (DMSA) (141 keV emission) and ¹⁸F-fluorodeoxyglucose (FDG) (511 keV emission) injected into a human volunteer. ^99mTc-DMSA and ¹⁸F-FDG were injected intravenously into a 25-year-old male volunteer. The distributions of ^99mTc-DMSA and ¹⁸F-FDG were simultaneously made visible by setting a specified energy window for each radioisotope. The images of these radiopharmaceuticals acquired using the prototype Compton camera were superimposed onto computed tomography images for reference. The reconstructed image showed that ^99mTc-DMSA had accumulated in both kidneys, which is consistent with the well-known diagnostic distribution determined by clinical imaging via single-photon emission computed tomography. In the ¹⁸F-FDG image, there is broad distribution around the liver and kidneys, which was expected based on routine clinical positron emission tomography imaging. The current study demonstrated for the first time that the Si/CdTe Compton camera was capable of simultaneously imaging the distributions of two radiopharmaceuticals, ^99mTc-DMSA and ¹⁸F-FDG, in a human body. These results suggest that the Si/CdTe Compton camera has the potential to become a novel modality for nuclear medical diagnoses enabling multi-probe simultaneous tracking.