TY - JOUR T1 - Development of a PET/EPRI simultaneous imaging system for assessing tumor hypoxia JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 526 LP - 526 VL - 60 IS - supplement 1 AU - Heejong Kim AU - Boris Epel AU - Subramanian Sundramoorthy AU - Hsiu-Ming Tsai AU - Eugene Barth AU - Howard Halpern AU - Chin-Tu Chen AU - Chien-Min Kao Y1 - 2019/05/01 UR - http://jnm.snmjournals.org/content/60/supplement_1/526.abstract N2 - 526Objectives: Quantitative assessment of tumor hypoxia [1] is important in cancer treatment and therapeutic planning. 18F-fluoromisonidazole (F-MISO) [2] and 64Cu-ATSM [3] have been used in PET imaging to measure tumor hypoxia. However, the efficacy of PET imaging based hypoxia targeting in radiation therapy is still inconclusive [4]. We are developing a combined imaging system of positron emission tomography (PET) and electron paramagnetic resonance imaging (EPRI) [5][6] to investigate the potential of PET imaging in assessing tumor hypoxia. The combined imaging system is to exploit the unique feature of EPRI, which measures partial pressure of oxygen (pO2) precisely in tissue [7][8], and the validity of PET imaging in tumor hypoxia is evaluated from simultaneously acquired EPRI. Methods: The EPRI component of the combined system is built with two permanent magnets (25 mT) and three gradient field coils for spatial encoding (the maximum 15mT/m), which are embedded in the permanent magnets. The distance between two permanent magnets is adjusted to be 12 cm to install a small animal imaging PET scanner [9], which was originally developed as an insert for MRI. The PET detector consists of total 14 detector modules, and each detector module uses of 8x4 LYSO arrays (3x3x10 mm3) coupled to two Hamamatsu S13361-3050NE-04 MPPC arrays (4x4, 3.2 mm pitch). The detector modules are installed within a cylindrical supporting structure with 60 mm inner diameter and 115 mm outer diameter. The axial field of view of the PET is 25.6 mm. The RF resonator of the EPRI, 19 mm diameter and 15 mm length, is placed at the center of the PET field of view. Results: The experiments to assess the compatibility of two imaging modality have been carried out by using 22Na point source or capillary tubes filled with FDG for PET and capillary tubes filled with Trityl solution for EPRI. The images of the phantom were obtained from the data acquired by running PET/EPRI simultaneously. The spatial resolution, ~1.5 mm for PET and ~1.0 mm for EPRI, in the images are retained as measured before the system integration. Any noticeable effects or artifacts in the co-registered images have not been observed. Conclusions: We have developed a PET/EPRI simultaneous imaging system in order to investigate it’s validity for assessing tumor hypoxia. Initial experiments with the combined system have been performed, and co-registered images of phantoms were obtained. The preliminary results show that the combined PET/EPRI system is performing well and ready to be deployed for in-vivo animal study. ER -