H Nguyen*, S Khan, N Das, A Natarajan, E Takematsu, G Pratx, Stanford University, Stanford, CA

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  H Nguyen

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SU-F-202-3 (Sunday, 7/10/2022) 2:00 PM - 3:00 PM [Eastern Time (GMT-4)]

Room 202

Purpose: Recent work has demonstrated the feasibility of tracking the migration of individual live cells in vivo using PET. This study examines a high-sensitivity dual-layer BGO/LSO PET scanner for imaging and tracking low-radioactivity cells and develops an algorithm that simultaneously tracks multiple radiolabeled single cells.

Methods: A dual-layer BGO/LSO PET scanner was first characterized to examine the intrinsic background of the scintillators for different lower energy thresholds (350– 450 keV). We scanned six static 37 cps 68Ga water droplets in oil at various time points to investigate the scanner’s detection limit. We also imaged seven 39 cps 18F water droplets phantom, including six static droplets and one moving in a helical path. Finally, FDG radiolabeled B16 single were also imaged. We applied two algorithms to track these low-radioactivity sources: a previously reported tracking algorithm developed for fluid mechanics investigations (PEPT-EM) and a novel version of this method that uses spline functions to improve the tracking quality (PEPT-EM-SP).

Results: The background recorded in the BGO layer was negligible (<1 cps), while in the LSO layer, above 90 cps was measured at 350 – 650 keV due to intrinsic 176Lu radioactivity; however, this background reduced significantly as the energy window narrowed. The PET scanner can detect 68Ga water droplets with radioactivity as low as 9 cps. The PEPT-EM tracking algorithm can precisely derive the location of the droplets using either BGO event only (low background) or all event types (high background). We also observed more precise 18F water droplets constructed trajectories resulting from PEPT-EM-SP than the PEPT-EM method.

Conclusion: This study indicates the potential for using a high-sensitivity dual-layer BGO/LSO PET scanner and a novel PEPT-EM-SP algorithm to simultaneously and accurately track multiple low-dose radiolabeled single cells in vivo. Tracking single radiolabeled cells within a mouse model is currently being investigated.

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