Presentation Evaluation of simultaneous dual-isotope SPECT/PET/CT imaging with 99mTc and 64Cu by phantom study and its in vivo application

Adachi, Naoya  ,  Yoshii, Yukie  ,  Furukawa, Takako  ,  Takeuchi, Yasuto  ,  Inubushi, Masayuki  ,  Wakizaka, Hidekatsu  ,  Ming-Rong, Zhang  ,  Fujibayashi, Yasuhisa  ,  Saga, Tsuneo

Objective: SPECT/PET/CT is useful to analyze behaviors of two probes with different functions. Recently, a new concept of SPECT/PET/CT imaging with VECTor small-animal scanner (MILabs) has been developed, which allows to obtain truly simultaneous dual-isotope images for SPECT/PET nuclides with high resolution by separating the photon energy using the collimator with clustered pinholes (Goorden et al. JNM 2013). In this study, we evaluated the quantitativity of simultaneous measurement with SPECT nuclide 99mTc and PET nuclide 64Cu using this system by phantom study and explored its in vivo application. Methods: Phantoms containing single isotope (99mTc or 64Cu) or dual isotopes with various concentrations and ratios were used. Radioactivity of the phantoms was measured by SPECT/PET/CT system. In in vivo study, simultaneous imaging with a hypoxia-detecting agent 64Cu-diacetyl-bis (N4-methylthiosemicarbazone) (64Cu-ATSM) and a blood pool agent 99mTc-human serum albumin (99mTc-HSA), was performed using HT-29 tumor-bearing mice. Results: In phantom study, radioactivity measured by SPECT/PET imaging was consistent with that enclosed in the phantoms, which was similar in both single- and dual-isotope phantoms (99mTc: 0-9.25 MBq, 64Cu: 0-18.5 MBq). The results were same, even when ratios were changed. In vivo study revealed that the distribution of hypoxic regions detected by 64Cu-ATSM was clearly distinguished from blood pool detected by 99mTc-HSA within HT-29 tumors. Conclusions: We showed the quantitativity of the SPECT/PET/CT system with 99mTc and 64Cu from phantom study. Also, we demonstrated the capability of the system in in vivo imaging with 64Cu-ATSM and 99mTc-HSA to simultaneously analyze tumor hypoxia and vascularity.
The International Chemical Congress of Pacific Basin Socie 2015

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